We have synthesized anthracene–acetylene oligomers, which contained one 10-substituted anthracene unit and one anthraquinone unit, by cyclization with Sonogashira coupling. X-ray analysis revealed an almost-planar framework and significant out-of-plane deformation around the inner carbonyl moiety because of steric hindrance. These compounds underwent self-association in solution and their association constants for monomer–dimer exchange were determined by variable-concentration ¹H NMR measurements in CDCl₃: 8 mol⁻¹ L (10-substituent: isopropyl), <5 mol⁻¹ L (methoxy), and 19 mol⁻¹ L (octyloxy). These results were discussed on the basis of spectroscopic and molecular-orbital analysis. A linear molecular assembly of the octyloxy compound at a liquid/graphite interface was observed by STM measurements.

A–A breakdown cover: π-Conjugated cyclic structures, which were constructed from two kinds of arene units and acetylene linkers, underwent self-association in solution because of intramolecular π⋅⋅⋅π interactions.

One thing leads to another: Bis(benzannelated) 5,6-spiroketal skeletons can be constructed by an efficient cascade process involving an unprecedented Cu^I-catalyzed intramolecular alkyne hydroalkoxylation and an asymmetric hetero-Diels–Alder cycloaddition. The method yields a series of diversely functionalized spiroketals from two readily available open-chained starting materials in good yields and excellent diastereoselectivities.

Herein, we calculated reorganization energies, vertical ionization energies, electron affinities, and HOMO–LUMO gaps of fused thiophenes and their derivatives, and analyzed the influence of different substituents on their electronic properties. Furthermore, we simulated the angular resolution anisotropic mobility for both electron- and hole-transport, based on quantum-chemical calculations combined with the Marcus–Hush electron-transfer theory. We showed that: 1) styrene-group substitution can effectively elevate the HOMO energy level and lower the LUMO energy level, and therefore lower both the hole- and electron-injection barriers; and 2) chemical oxidation of the thiophene ring can significantly improve the semiconductor properties of the fused oligothiophenes through a decrease of the injection barrier and an increase in the charge-transfer mobility for electrons but without lowering their hole-transfer mobilities, which suggests that it may be a promising way to convert p-type semiconductors into ambipolar or n-type semiconductor materials.

Strong as an Ox: Chemical oxidation of the thiophene ring of fused thiophenes and their derivatives could significantly improve their semiconductor properties, which suggests it may be a promising way to convert p-type semiconductors into ambipolar or n-type semiconductors.

Switch ’em up: Two-electron oxidation and reduction switches the title complexes between aromatic and antiaromatic character (see picture). The switching is confirmed by ¹H NMR and UV/Vis/NIR absorption spectroscopy and by cyclic voltammetry. The structure of the porphyrin–[26]hexaphyrin hybrid tape was elucidated by X-ray diffraction analysis.

Direct CH phenylation of 2-ethylthiophene and 2-chlorothiophene with PhPdI(bipy) complex to form either the corresponding 4-phenyl or 5-phenylthiophene derivative is studied under stoichiometric conditions using various Lewis acids as additives. It is shown that reactions occur via the corresponding cationic Pd complex (PhPdbipy⁺) and that the counteranion determines the regioselectivity. High-level DFT calculations reveal that CC bond formation occurs via a carbopalladation pathway and not via electrophilic palladation. These calculations give some indications regarding the regioselectivity of the thiophene arylation.

The counteranion does the job! Reactions of 2-substituted thiophenes with cationic PhPdbipy complexes afforded either the corresponding C(4) or C(5)-phenylated thiophene derivatives depending on the counteranion present. DFT calculations revealed that reactions occur via carbopalladation and not via electrophilic palladation.

The first total synthesis of the hybrid ganglioside X2, which consisted of a highly branched octasaccharide and ceramide moieties, was accomplished by using a glucosyl ceramide cassette approach. With a disaccharyl donor, the heptasaccharide could not be constructed by glycosylation of the C4 hydroxy group of galactose at the reducing end of the pentasaccharide. In contrast, through an alternative approach with two branched glycan units, a GM2-core trisaccharide, and a lacto-ganglio tetrasaccharide, the heptasaccharyl donor could be prepared and subsequently joined with a glucosyl ceramide cassette to afford the protected ganglioside, X2. Finally, global deprotection completed the synthesis, thus affording the pure ganglioside X2.

Here the buddy comes: Structurally analogous gangliosides (X1 and X2) are associated with an amyotrophic lateral sclerosis (ALS)-like disorder. The synthesis of 30.6 mg X2 was achieved by using a glucosyl ceramide cassette approach.

The direct detection of nanoparticles is at the forefront of research owing to their environmental and toxicological applications. Herein, we studied the inherent electrochemistry of Ni and NiO nanoparticles and proposed a simple and direct electrochemical method for the determination of the concentrations of both nickel (Ni) and nickel oxide (NiO) nanoparticles in alkaline solution. A highly sensitive voltammetry technique was used to measure the oxidative signal of Ni(OH)₂ that formed spontaneously on the surface of Ni and NiO nanoparticles in alkaline media. Detection limits of 220 μg mL⁻¹ for Ni and 13 μg mL⁻¹ for NiO nanoparticles were obtained. Ni and NiO nanoparticles are used as electrode modifiers or as electrochemical signal labels in various biosensing applications. Therefore, methods to rapidly quantify the amount of Ni and NiO nanoparticles are of widespread potential use.

Metode elektrokimia sederhana untuk menentukan konsentrasi nanopartikel nikel dan nikel(II) oksida (Ni, NiO) dalam larutan alkali diajukan dalam artikel ini. Teknik voltametri pulsa diferensial digunakan untuk melakukan pengukuran sensitif terhadap sinyal oksidasi Ni(OH)₂ yang terbentuk secara spontan pada permukaan nanopartikel Ni dan NiO dalam media alkali. Limit deteksi yang dicapai untuk Ni adalah 220 μg mL⁻¹ dan untuk NiO adalah 13 μg mL⁻¹. Nanopartikel Ni dan NiO dapat digunakan untuk memodifikasi elektrode atau sebagai label sinyal elektrokimia untuk diaplikasikan dalam sensor biologi. Oleh sebab itu, metode untuk mengkuantifikasi jumlah nanopartikel Ni dan NiO memiliki potensi penerapan.

Down on one Ni: The direct detection of nanoparticles is at the forefront of research owing to its environmental and toxicological applications. A simple and direct electrochemical method is proposed for the determination of the concentration of both nickel (Ni) and nickel oxide (NiO) nanoparticles in alkaline solution.

Nanowall materials are ideal two-dimensional structures with high surface-to-volume ratios and open edge geometries. We first report on the growth and characterization of indium oxide nanowalls on transparent and conducting indium tin oxide substrates. The nanosheets that compose the nanowalls are single-crystalline and are approximately 8 nm in thickness. The density and the lateral dimensions of the nanosheets on the substrate can be controlled by the growth time. Adopting a bridgework-like strategy, we directly construct indium oxide nanowall gas sensors on the patterned indium tin oxide substrates. The pattern lines on the substrates are etched using transparent plastic adhesive tape as shadow mask, which is both simple and cheap in comparison with the conventional photolithography technique. The sensors exhibit fast response/recovery behavior and good reproducibility to NO₂ gas under mild testing conditions, such as room temperature, ambient pressure, dry air background, and 1.5 V dc bias, and can achieve a detection limit as low as 50 ppb. We propose an assumption that the gas adsorption is composed of deep adsorption and probe adsorption to explain the interesting gas-sensing behavior of the indium oxide nanowalls. We suggest that the work reported herein, including the facile growth of indium oxide nanowalls, the bridgework-like strategy to directly construct electronic devices, and the high gas-sensing performance of the indium oxide nanowalls sensors, is a significant step towards the real applications of novel semiconductor nanostructures.

Great walls from China: By directly growing In₂O₃ nanowalls (see picture), which are comprised of vertically grown ultrathin single-crystalline In₂O₃ nanosheets, on patterned ITO substrates, electronic devices such as gas sensors can be easily constructed by the bottom-up method based on a smart bridgework-like strategy, which demonstrated a detection limit as low as 50 ppb to NO₂ under mild conditions.

Two new benzotriazole-bridged sensitizers are designed and synthesized (BTA-I and BTA-II) containing a furan moiety for dye-sensitized solar cells (DSSCs). Two corresponding dyes (BTA-III and BTA-IV) with a thiophene spacer were also synthesized for comparison. All of these dyes performed as sensitizers for DSSCs, and the photovoltaic performance data of these benzotriazole-bridged dyes showed a high open-circuit voltage (V_oc: 804–834 mV). Among the four dyes, DSSCs based on BTA-II, with a furan moiety and branched alkyl chain, showed the highest V_oc (834 mV), a photocurrent density (J_sc) of 12.64 mA cm⁻², and a fill factor (FF) of 0.64, corresponding to an overall conversion efficiency (η) of 6.72 %. Most importantly, long-term stability of the BTA-I–IV-based DSSCs with ionic-liquid electrolytes under 1000 h light-soaking was demonstrated, and BTA-II exhibited better photovoltaic performance of up to 5.06 % power conversion efficiency.

Let the light shine: Two new benzotriazole-bridged dyes containing a furan moiety for DSSCs have been synthesized. DSSCs based on the dye with a furan and branched alkyl chain showed a high open-circuit voltage of 834 mV (see picture). Most importantly, long-term stability these DSSCs with ionic-liquid electrolytes under 1000 h light-soaking was demonstrated and exhibited good photovoltaic performance of up to 5.06 % power conversion efficiency.

Shine on: In this mercury(II) sensing approach, the non-fluorescent probe SAN undergoes Hg²⁺-promoted deprotection reaction, resulting in the formation of the two-photon-fluorescent product AAN. The system shows high sensitivity and selectivity and also can be used in live-cell environments.

Five rare-earth–transition-metal (RE–TM) heterometal organic–inorganic hybrids based on Keggin-type silicotungstates and mixed ligands H2pzda (pzda=pyrazine-2,3-dicarboxylate) and en (en=ethylenediamine) (enH2)[Cu(en)2(H2O)]2{[Cu(en)2][Cu(en)2(H2O)][(α-SiW11 O39)RE(H2O)(pzda)]}2⋅n H2O (n≈4; RE=YIII (1), DyIII (2), YbIII (3), and LuIII (4)) and [Cu(en)2(H2O)]2{[Cu(en)2]2[Cu(pzda)2][(α-H2SiW11O39)Ce(H2O)]2}⋅n H2O (5; n≈8) have been hydrothermally synthesized and structurally characterized. Compounds 1–5 all contain the dimeric mono-RE substituted Keggin [RE(α-SiW11O39)]210− subunits linked by H2pzda ligands. Interestingly, 1–4 exhibit discrete structures, in which the H2pzda ligand acts as a tetradentate ligand to bind the RE and Cu cations, whereas 5 displays a 1D double-chain architecture, in which the H2pzda ligand adopts a new pentadentate mode to connect the Ce and Cu cations. To our knowledge, 1–5 represent the first monovacant Keggin-type silicotungstates containing both RE–TM heterometals and mixed ligands. The luminescence of 2 is derived from the combination of the DyIII cations and H2pzda ligands, whereas the luminescence properties of 1 and 3–5 are attributable to the H2pzda ligands.

A rare find: Two types of organic–inorganic hybrid monovacant Keggin silicotungstates with both rare-earth–transition-metal heterometals and mixed ligands (H₂pzda and ethylenediamine; pzda=pyrazine-2,3-dicarboxylate) were separated and characterized.

Stay tuned: Tuning the excited state lifetimes of Ru^II polypyridyl complexes is the key to their potential applicabilities, for example, as photosensitizers. This work demonstrates that the different emissive properties of two similar Ru^II polypyridyl complexes bearing peripheral ligand substitution are governed by the radiative decay rates and not the energy gap law.

For your I’s only: A new imidazolium-based fluorescent cyclophane 1 was designed and synthesized that was quenched selectively in the presence of iodide but not other anions, as assessed by fluorimetry. In addition, fluorescence titration experiments, ¹H NMR spectroscopic data, and theoretical calculations provide evidence that 1 encapsulates two iodides inside its cavity.

Through the cleavage of the CC bond, the first catalytic tandem conjugate addition–elimination reaction of Morita–Baylis–Hillman C adducts has been presented. Various S_N2′-like C-, S-, and P-allylic compounds could be obtained with exclusive E configuration in good to excellent yields. The Michael product could also be easily prepared by tuning the β-C-substituent group of the α-methylene ester under the same reaction conditions. Calculated relative energies of various transition states by DFT methods strongly support the observed chemoselectivity and diastereoselectivity.

Competitive choice: Through the cleavage of the CC bond, the catalytic tandem conjugate addition–elimination reaction of Morita–Baylis–Hillman C adducts has been disclosed. Various S_N2′-like C-, S-, and P-allylic compounds are prepared with exclusive E configuration in good to excellent yield. The origin of the selectivity was strongly supported by DFT methods (see scheme).

A simple and practical technique to synthesize nanosized platinum particles loaded on TiO₂ (Pt–TiO₂) by using a microwave (Mw)-assisted deposition method has been exploited in the development of a highly efficient photocatalyst for the formation of H₂ and N₂ gases from harmful nitrogen-containing chemical wastes, for example, aqueous ammonia (NH₃). Upon Mw irradiation, a platinum precursor can be deposited quickly on the TiO₂ surface from an aqueous solution of platinum and subsequent reduction with H₂ affords the nanosized platinum metal particles with a narrow size distribution (Mw-Pt–TiO₂). Characterization by CO adsorption, platinum L_III-edge X-ray absorption fine structure analysis, and TEM analysis revealed that the size of the metal nanoparticles strongly depended on the preparation methods. Smaller platinum nanoparticles were obtained by the Mw heating method than those obtained by conventional preparation techniques, such as photoassisted deposition (PAD), impregnation (Imp), and equilibrium adsorption (EA) deposition by conventional convective heating. The H₂ and N₂ formation rates increased with increasing dispersity of platinum. Pt–TiO₂ prepared by the Mw heating method exhibited a specifically high H₂ formation activity in the photocatalytic decomposition of aqueous NH₃ in a nearly stoichiometric 3:1 (H₂/N₂) molar ratio under inert conditions. The present Mw heating method is applicable to a variety of anatase-type TiO₂ species possessing different specific surface areas to provide small and highly dispersed platinum nanoparticles with a narrow size distribution.

Nuked catalysts! Nanosized platinum particles loaded on TiO₂ (Pt–TiO₂) were synthesized by using a microwave-assisted deposition method with the aim of developing a highly efficient photocatalyst for the decomposition of aqueous NH₃ into H₂ and N₂ in a stoichiometric molar ratio under inert conditions (see picture).

The first enantioselective synthesis of cytotoxic natural products rigidiusculamides A (ent-21) and B (8) has been achieved by two synthetic routes. The first one is convergent based on the common intermediate 11, obtained through a high yielding SmI₂-mediated Reformatsky-type reaction. A highly diastereoselective one-pot Dess–Martin periodinane-mediated bis-oxidation allowed the direct conversion of the diastereomeric mixture of 11 into rigidiusculamide B (8). Isolation of minor diastereomer 21, in combination with computational work, allowed us to suggest the structure of the natural rigidiusculamide A to be ent-21, as synthesized by the second route. Four diastereomers (7, ent-7, 22 a, and 22 b) and an enantiomer (21) of rigidiusculamide A (ent-21) have been synthesized. On the basis of literature precedents and computational work, a biosynthetic pathway for rigidiusculamides A and B was proposed to account for the opposite configuration at C-5 of those two congeners.

Proof of form: The first enantioselective syntheses of cytotoxic natural products rigidiusculamides A (ent-21) and B (8) are reported. The revised structure of rigidiusculamide A (ent-21) was proposed on the basis of the isolation of six diastereomers, including the structure originally proposed for rigidiusculamide A (7).

The addition of electrophilic reagents to the carbon–carbon double bond is one of the most fundamental reactions in organic chemistry. Halogen electrophiles constitute probably the most important class of electrophiles and have been widely used to induce electrophilic addition reactions to alkenes like halolactonizations or dihalogenations. Despite their long history and high importance, catalytic, asymmetric variants of these reactions have been underdeveloped until very recently. During the last two years this has changed and many novel approaches have been reported. This review aims to cover these new developments through discussing the common themes as well as the suggested mechanistic scenarios.

Technical difficulties: Enantioselective, electrophilic halogen additions to alkenes have often been described as difficult reactions. Recently, this problem has been addressed with many novel catalytic methods. In this focus review these methods will be summarized highlighting common themes and mechanistic considerations.

The efficient, regioselective synthesis of functionalized/annulated quinolines was achieved by the coupling of 2-aminoaryl ketones with alkynes/active methylenes/α-oxoketene dithioacetals promoted by InCl₃ in refluxing acetonitrile as well as under solvent-free conditions in excellent yields. This transformation presumably proceeded through the hydroamination–hydroarylation of alkynes, and the Friedländer annulation of active methylene compounds and α-oxoketene dithioacetals with 2-aminoarylketones. In addition, simple reductive and oxidative cyclization of 2-nitrobenzaldehyde and 2-aminobenzylalcohol, respectively, afforded substituted quinolines. Systematic optimization of the reaction parameters allowed us to identify two-component coupling (2CC) conditions that were tolerant of a wide range of functional groups, thereby providing densely functionalized/annulated quinolines. This approach tolerates the synthesis of various bioactive quinoline frameworks from the same 2-aminoarylketones under mild conditions, thus making this strategy highly useful in diversity-oriented synthesis (DOS). The scope and limitations of the alkyne-, activated methylene-, and α-oxoketene dithioacetal components on the reaction were also investigated.

In it to wIn it: The regioselective synthesis of functionalized/annulated quinolines involved the coupling of 2-aminoaryl/alkyl ketones with alkynes/activated-methylenes/α-oxoketene-dithioacetals promoted by InCl₃ in MeCN as well as under solvent-free conditions. Simple reductive and oxidative cyclization of 2-nitrobenzaldehyde and 2-aminobenzyl alcohol, respectively, has also been performed to give substituted quinolines.

Mixed-donor atom tetramethoxy resorcinarene bis-thiacrown hosts, in which the crown unit contains both hard oxygen and soft sulfur donor atoms, were synthesized for soft metal cation binding. The binding properties were investigated both in solution and in the solid state by NMR spectroscopy and X-ray crystallography. It was found that the resorcinarene bis-thiacrowns were able to complex silver cations with remarkable affinity forming readily 1:2 host–guest complexes in solution. The solid state structures also revealed that the bis-thiacrowns form silver complexes in an unanticipated endo- and exo-cavity fashion within the same host molecule. Both the solution and solid state studies indicated the sulfur atoms to be the major contributing donor atoms in forming the binding interactions with silver cations.

Tioeetterisilloitettuja tetrametoksiresorsinareeneja valmistettiin sitomaan pehmeitä metallikationeja kuten hopeaa. Sitoutumisominaisuuksia tutkittiin sekä liuoksessa että kiinteässä tilassa hyödyntäen NMR-spektroskopiaa ja yksikideröntgenkristallografiaa. Tutkimuksissa huomattiin bistiakruunujen sitovan hopeakationeja huomattavalla affiniteetilla ja liuoksessa 1:2 isäntä-vieraskompleksit muodostuivat nopeasti. Kiinteän tilan rakenteet paljastivat yllättävän hopeakationin endo- ja ekso-sitoutumisen samassa resorsinareenimolekyylissä, jossa toinen hopeakationi oli sitoutuneena resorsinareenin onkalon sisään ja toinen sen ulkopuolelle. Sekä liuos- että kiinteätilan tutkimuksissa huomattiin rikkiatomien muodostavan merkittävimmät sitomisvuorovaikutukset hopeakationin kanssa.

Binding it soft but strong: Resorcinarene bis-thiacrowns containing soft sulfur donor atoms are shown to be ideal host molecules for high-affinity encapsulation of silver inside the resorcinarene cavity. A 1:2 host–guest binding was observed both in solution and in the solid state.

We have developed a ladder-type dithienocyclopentathieno[3,2-b]thiophene (DTCTT) hexacyclic unit in which the central thieno[3,2-b]thiophene ring was covalently fastened to two adjacent thiophene rings through carbon bridges, thereby forming two connected cyclopentadithiophene (CPDT) units in a hexacyclic coplanar structure. This stannylated Sn-DTCTT building block was copolymerized with three electron-deficient acceptors, dibromo-thieno[3,4-c]pyrrole-4,6-dione (TPD), dibromo-benzothiadiazole (BT), and dibromo-phenanthrenequinoxaline (PQX), by Stille polymerization, thereby furnishing a new class of alternating donor–acceptor copolymers: PDTCTTTPD, PDTCTTBT, and PDTCTTPQX, respectively. Field-effect transistors based on PDTCTTPQX and PDTCTTBT yielded high hole mobilities of 0.017 and 0.053 cm² V⁻¹ s⁻¹, respectively, which are among the highest performances among amorphous donor–acceptor copolymers. A bulk heterojunction solar cell that incorporated PDTCTTTPD with the lower-lying HOMO energy level delivered a higher V_oc value of 0.72 V and a power conversion efficiency (PCE) value of 2.59 %.

Snakes and ladders: Donor–acceptor polymers based on the ladder-type dithienocyclopentathieno[3,2-b]thiophene (DTCTT) unit has promising performance for solution-processed organic transistors and photovoltaics.

Triquinacene is a concave tricyclic hydrocarbon with diverse photoreactivity. In the cavity of an electron-accepting molecular host, triquinacene was specifically photooxidized at the peripheral allylic position into an alcohol, 1-hydroxytriquinacene, via guest-to-host electron transfer. The unusual reactivity stems from the extremely electron-deficient triazine panel ligand of the host cage, which allows the cage to function as a good electron acceptor. Thus, self-assembled coordination cages can serve not only as molecular-sized reaction vessels but also function electronically as redox media. Dissolved molecular oxygen is indispensable for the photoreaction and immediately traps a photogenerated radical.

Electron-withdrawing cage: A self-assembled coordination cage accommodates triquinacene (1) to allow a specific photooxidation of the peripheral allylic position via guest-to-host electron transfer. The host cage consists of electron-deficient triazine panels and thus serves as a photochemically active molecular container.

Golden donuts: Polystyrene-block-poly(2-vinylpyridine) block copolymer (BCP) corpuscle templates were prepared on PS-modified substrates. Subsequent metal–polymer complexation and reduction resulted in the formation of gold double-ring structures.

Ruthenium(III)-substituted α-Keggin-type silicotungstates with pyridine-based ligands, [SiW₁₁O₃₉Ru^III(Py)]⁵⁻, (Py: pyridine (1), 4-pyridine-carboxylic acid (2), 4,4′-bipyridine (3), 4-pyridine-acetamide (4), and 4-pyridine-methanol (5)) were prepared by reacting [SiW₁₁O₃₉Ru^III(H₂O)]⁵⁻ with the pyridine derivatives in water at 80 °C and then isolated as their hydrated cesium salts. These compounds were characterized using cyclic voltammetry (CV), UV/Vis, IR, and ¹H NMR spectroscopy, elemental analysis, titration, and X-ray absorption near-edge structure (XANES) analysis (Ru K-edge and L₃-edge). Single-crystal X-ray analysis of compounds 2, 3, and 4 revealed that Ru^III was incorporated in the α-Keggin framework and was coordinated by pyridine derivatives through a RuN bond. In the solid state, compounds 2 and 3 formed a dimer through ππ interaction of the pyridine moieties, whereas they existed as monomers in solution. CV indicated that the incorporated Ru^III–Py was reversibly oxidized into the Ru^IV–Py derivative and reduced into the Ru^II–Py derivative.

Py in the sky: Preparation, structural characterization, and redox studies of Ru^III–pyridine-substituted α-Keggin-type silicotungstate hybrid molecules, [SiW₁₁O₃₉Ru^III(Py)]⁵⁻, are reported. Ru^IV was stabilized in silicotungstate.

We have previously reported that the trimeric Zn²⁺–cyclen complex (tris(Zn²⁺–cyclen), [Zn₃L¹]⁶⁺) and the trianion of trithiocyanuric acid (TCA³⁻) assembled in a 4:4 ratio to form a cuboctahedral supramolecular cage, [(Zn₃L¹)₄(TCA³⁻)₄]¹²⁺ (hereafter referred to as a Zn–cage), in neutral aqueous solution (cyclen=1,4,7,10-tetraazacyclododecane). Herein, we examined the molecular recognition of C₁–C₁₂ hydrocarbons (C_nH_(2n+2) (n≈1–12)), cyclopentane, cyclododecane, cis-decalin, and trans-decalin by the Zn–cage under normal atmospheric pressure. This cage complex was also able to encapsulate guest molecules that had larger volumes than that of the inner cavity of the Zn–cage, thereby suggesting that the inner shape of the Zn–cage was flexible. Computational simulations of Zn–cage–guest complexes provided support for this conclusion. Moreover, the solvent-accessible surface areas (SASA) of the Zn–cage host, guest molecules, and the Zn–cage-guest complexes were calculated and the data were used to explain the order of stability determined by the guest-replacement experiments. The storage of volatile molecules in aqueous solution by the Zn–cage is also discussed.

Be our guest: Molecular recognition of hydrocarbon guests by the 4:4 supramolecular complex of tris(Zn²⁺-cyclen) and trithiocyanurate is reported. Computational simulation of (2)¹²⁺–guest complexes supports its structural flexibility.

The reactions of two diaminotriazine ligands 2,4-diamino-6-(2-pyridyl)-1,3,5-triazine (2-pydaT) and 6-phenyl-2,4-diamino-1,3,5-triazine (PhdaT) with ruthenium–arene precursors led to a new family of ruthenium(II) compounds that were spectroscopically characterized. Four of the complexes were cationic, with the general formula [(η⁶-arene)Ru(κ²-N,N-2-pydaT)Cl]X (X=BF₄, TsO; arene=p-cymene: 1⋅BF₄, 1⋅TsO; arene=benzene: 2⋅BF₄, 2⋅TsO). The neutral cyclometalated complex [(η⁶-p-cymene)Ru(κ²-C,N-PhdaT*)Cl] (3) was also isolated. The structures of complexes 2⋅BF₄ and 3⋅H₂O were determined by X-ray diffraction. Complex 1⋅BF₄ underwent a partial reversible-aquation process in water. UV/Vis and NMR spectroscopic measurements showed that the reaction was hindered by the addition of NaCl and was pH-controlled in acidic solution. At pH 7.0 (sodium cacodylate) Ru–Cl complex 1⋅BF₄ was the only species present in solution, even at low ionic strength. However, in alkaline medium (KOH), complex 1⋅BF₄ underwent basic hydrolysis to afford a Ru–OH complex (5). Fluorimetric studies revealed that the interaction of complex 1⋅BF₄ with DNA was not straightforward; instead, its main features were closely linked to ionic strength and to the [DNA]/complex ratio. The bifunctional complex 1⋅BF₄ was capable of interacting concurrently through both its p-cymene and 2-pydaT groups. Cytotoxicity and genotoxicity studies showed that, contrary to the expected behavior, the complex species was biologically inactive; the formation of a Ru–OH complex could be responsible for such behavior.

Ru lonesome tonight? A new family of Ru^II-arene complexes with two different diaminotriazine ligands were synthesized. Bifunctional interactions of complex 1⋅BF₄ with DNA through two concurrent binding modes were considered: groove binding (mode 1) concurred with a quenching effect, whereas electrostatic binding (mode 2) implicated the p-cymene ring and promoted an increase in fluorescence.

Well-ordered mesoporous Pt nanoparticles (MPNs) with uniform olive shapes are synthesized by using two-dimensional (2D) hexagonal mesoporous silica (SBA-15) as a hard template. The average particle sizes are controllable in the range of 150 to 230 nm by changing the reduction time. Low-angle XRD profiles for the obtained MPNs show three distinct peaks assignable to the (10), (11), and (20) planes of a highly ordered 2D hexagonal symmetry. From high-magnification SEM images, periodically arranged Pt nanowires are observed clearly, which are a negative replica of the 2D hexagonally ordered mesoporous silica (SBA-15). Furthermore, the single crystallinity of the Pt fcc structure coherently extends over the whole particles. As a result of such unique character as well as high surface area, the obtained MPNs show distinctly enhanced electrocatalytic properties for methanol oxidation reaction compared to other Pt samples, such as Pt black.

Antipasti, anyone? Well-ordered olive-shaped mesoporous Pt nanoparticles (see picture) can be prepared by using two-dimensional (2D) hexagonal mesoporous silica (SBA-15) as a hard template. The average particle sizes are controllable in the range of 150 nm to 230 nm by changing the deposition time.

Graphene research is currently at the frontier of electrochemistry. Many different graphene-based materials are employed by electrochemists as electrodes in sensing and in energy-storage devices. Because the methods for their preparation are inherently different, graphene materials are expected to exhibit different electrochemical behaviors depending on the functionalities and density of defects present. Electrochemical treatment of these “chemically modified graphenes” (CMGs) represents an easy approach to alter surface functionalities and consequently tune the electrochemical performance. Herein, we report a preliminary electrochemical characterization of four common chemically modified graphenes, namely: graphene oxide, graphite oxide, chemically reduced graphene oxide, and thermally reduced graphene oxide. These CMGs were compared with graphite as a reference material. Cyclic voltammetry was used to ascertain the chemical functionalities present and to understand the potential ranges in which the materials were electroactive. Electrochemical treatment with either an oxidative or a reductive fixed potential were then carried out to activate these chemically modified graphenes. The effects of such electrochemical treatments on their electrocatalytic properties were then investigated by cyclic voltammetry in the presence of well-known redox probes, such as [Fe(CN)₆]^4−/3−, Fe^3+/2+, [Ru(NH₃)₆]^2+/3+, and ascorbic acid. Thermally reduced graphene oxide exhibited the best electrochemical behavior amongst all of the CMGs, with the fastest rate of heterogeneous electron transfer (HET) and the lowest overpotentials. These findings will have far-reaching consequences for the evaluation of different CMGs as electrode materials in electrochemical devices.

Electrochemical treatment of chemically modified graphenes (CMGs) represents an easy approach to alter surface functionalities and consequently tune electrochemical performance.

New covalently C₆₀-conjugated phthalocyanine (Pc) analogues in which the Pc and C₆₀ components are connected by means of a four-membered ring have been synthesized by taking advantage of a [2+2] cycloaddition reaction of C₆₀ with benzyne units generated from either a phthalocyanine derivative (8) or its precursor (1). The reaction of 1 with PhI(OAc)₂ and trifluoromethanesulfonic acid (TfOH) followed by the [2+2] cycloaddition of C₆₀ in the presence of tetra-n-butylammonium fluoride (TBAF) yielded the C₆₀-substituted Pc precursor (3). Mixed condensation of 3 and 4,5-dibutylsulfonylphthalonitrile (4) in a thermally promoted template reaction using a nickel salt successfully gave the Pc–C₆₀ conjugate (5). Results of mass spectrometry and ¹H and ¹³C NMR spectroscopy clearly indicate the formation of the anticipated Pc–C₆₀ conjugate. Direct coupling of C₆₀ with the Pc analogue that contained eight peripheral trimethylsilyl (TMS) groups (8) also proceeded successfully, such that mono and bis C₆₀-adducts were detected by their mass, although the isolation of each derivative was difficult. The absorption and magnetic circular dichroism (MCD) spectra of 5 and the reference compound (7) differ from each other in the Q-band region, thereby suggesting that the presence of the C₆₀ moiety affects the electronic structure of the conjugate. The reduction and oxidation potentials of 5 and 7 obtained by cyclic voltammetry are comparative, except for the C₆₀-centered reduction couple at −1.53 V versus Fc⁺/Fc in o-dichlorobenzene (o-DCB). A one-electron reduction of 5 and 7 in tetrahydrofuran (THF) by using the sodium mirror technique results in the loss of band intensity in the Q-band region, whereas the characteristic marker bands for Pc-ring-centered reduction appear at around 430, 600, and 900 nm for both compounds. The final spectral shapes of 5 and 7 upon the reduction resemble each other, thus indicating that no significant molecular orbital (MO) interactions between the C₆₀ and Pc units are present for the reduced species of 5. In contrast, the oxidized species of 5 and 7 generated by the addition of NOBF₄ in CH₂Cl₂ show significantly different absorption spectra from each other. Whereas the broad bands at approximately 400–550 nm of 7⁺ are indicative of the cationic π-radical species of metallo-Pcs and can be assigned to a transition from a low-lying MO to the half-filled MO, no corresponding bands were observed for 5⁺. These spectral characteristics have been tentatively assigned to the delocalized occupied frontier MOs for 5⁺. The experimental results are broadly supported by DFT calculations.

Wedding ring: Covalently C₆₀-conjugated phthalocyanine (Pc) analogues in which the Pc and C₆₀ components are joined by a four-membered ring have been synthesized by taking advantage of a [2+2] cycloaddition reaction of C₆₀ with benzyne units generated from either a Pc derivative or its precursor (see figure). The presence of the C₆₀ moiety affects the electronic structure of the conjugates.

New organic dyes containing pyrenylamine donors in a cascade arrangement and cyanoacrylic acid acceptors have been synthesized and characterized by optical, electrochemical, and theoretical studies. The dyes inherit a D-π¹-D-π²-A (D=donor, A=acceptor) molecular architecture where the π linkers π¹ are changed from phenyl to biphenyl and fluorene, whereas the π linker π² that connects the donor fragment with the acceptor is a phenyl unit. The conjugation pathway linking the two donor segments has been found to play a major role in the optical and electrochemical properties. Shorter π linkers such as phenyl groups facilitate the donor–acceptor interaction while the nonplanar biphenyl spacer decreases the electronic communication between the donors and enhances the oxidation propensity of the corresponding dye. All the dyes display an intense longer wavelength electronic transition,which is attributable to the amine-to-cyanoacrylic acid charge transfer. The extinction coefficient of this peak grows dramatically on increasing the conjugation pathway length between the two donor segments. The dyes were used as sensitizers in nanocrystalline TiO₂-based dye-sensitized solar cells (DSSCs) and the cascade donor system contributed to the enhancement in the device efficiency due to favorable absorption and redox properties.

New organic dyes containing pyrenylamine-based cascade donors have been synthesized and characterized by their optical and electrochemical properties. They showed interesting modulation in electronic properties, which are attributable to the changes in the electronic interaction between the donor segments arising from the nature of the linker.

Pure organic: The synthesis of tetrasubstituted furans often involves transition-metal catalysis or metal–halogen exchange reactions. A new approach to these heterocycles employs the Feist–Bénary addition–elimination process using nitroallylic acetates and 1,3-dicarbonyls (see scheme; X=C, O).

Hidden treasure: Gold nanoparticles (AuNPs) within a single protein crystal of lysozyme (see scheme, pink) are shown to efficiently catalyze the reduction of p-nitrophenol by NaBH₄, and the catalytic activity initially increased with increased size of AuNPs until the size reached 7.4 nm, after which the activity decreased with increasing size of the AuNPs. The use of chemicals to either accelerate or inhibit the activity is also demonstrated.

The ring-fused thiophene derivatives benzo[c]thiophene and its precursor bicyclo[2.2.2]octadiene (BCOD) have been introduced as π-conjugated spacers for organic push–pull sensitizers with dihexyloxy-substituted triphenylamine as donor and cyanoacrylic acid as acceptor (OL1–OL6). The effects of the fused ring on the spectroscopic and electrochemical properties of these sensitizers and their photovoltaic performance in dye-sensitized solar cells have been evaluated. Introduction of a binary benzo[c]thiophene and ethylenedioxy thiophene as π bridge caused a significant red shift of the characteristic intramolecular charge-transfer band to 642 nm. It is found that the sensitizer OL3, which contains one benzo[c]thiophene unit as π linker, gives the highest overall conversion efficiency of 5.03 % among all these dyes.

Sensitive souls: A series of sensitizers for dye-sensitized solar cells features ring-fused thiophene bridges between donor and acceptor moieties. The absorption spectra of the push–pull sensitizers all exhibit intense intramolecular charge transfer bands in the visible region (see picture), and solar cells based on the dyes show good incident photon to current conversion efficiencies.

Lanthanide-doped upconversion nanoparticles (UCNPs) have attracted considerable attention for their application in biomedicine. Here, silica-coated NaGdF₄:Yb,Er/NaGdF₄ nanoparticles with a tetrasubstituted carboxy aluminum phthalocyanine (AlC₄Pc) photosensitizer covalently incorporated inside the silica shells were prepared and applied in the photodynamic therapy (PDT) and magnetic resonance imaging (MRI) of cancer cells. These UCNP@SiO₂(AlC₄Pc) nanoparticles were uniform in size, stable against photosensitizer leaching, and highly efficient in photogenerating cytotoxic singlet oxygen under near-infrared (NIR) light. In vitro studies indicated that these nanoparticles could effectively kill cancer cells upon NIR irradiation. Moreover, the nanoparticles also demonstrated good MR contrast, both in aqueous solution and inside cells. This is the first time that NaGdF₄:Yb,Er/NaGdF₄ upconversion-nanocrystal-based multifunctional nanomaterials have been synthesized and applied in PDT. Our results show that these multifunctional nanoparticles are very promising for applications in versatile imaging diagnosis and as a therapy tool in biomedical engineering.

Go on, liver little: NaGdF₄:Yb,Er/NaGdF₄ nanoparticles with a carboxy aluminum phthalocyanine (AlC₄Pc) photosensitizer incorporated inside silica shells were used in photodynamic therapy and magnetic resonance imaging (MRI) of liver cancer cells. In vitro studies indicated that these nanoparticles effectively killed cancer cells upon near-infrared excitation. This work has potential applications in imaging-guided therapy.

Photocatalytic water splitting using semiconductor photocatalysts has been considered as a “green” process for converting solar energy into hydrogen. The pioneering work on electrochemical photolysis of water at TiO₂ electrode, reported by Fujishima and Honda in 1972, ushered in the area of solar fuel. As the real ultimate solution for solar fuel-generation, overall water splitting has attracted interest from researchers for some time, and a variety of inorganic photocatalysts have been developed to meet the challenge of this dream reaction. To date, high-efficiency hydrogen production from pure water without the assistance of sacrificial reagents remains an open challenge. In this Focus Review, we aim to provide a whole picture of overall water splitting and give an outlook for future research.

A split personality: Water splitting to produce H₂ and O₂ using solar energy in the presence of photocatalysts has been considered for the supply of clean, recyclable energy. Over the past few decades, a number of inorganic photocatalytic materials for overall water splitting have been developed. This review aims to sum up these research efforts, whilst providing a comprehensive understanding of this field.

Soothes your nerves: The enantiomerically enriched cis-1,2-dihydrocatechol 4 has been converted, over 16 steps including one involving an intramolecular Diels–Alder reaction, into the sesquiterpenoid natural product khusiol (3), which is structurally related to the neurite outgrowth-promoting natural product 11-O-debenzoyltashironin (1).

Let’s twist again: A “clean reaction” strategy based on thermally eliminating lactam bridges from a soluble acene precursor through a retro-Diels–Alder reaction gives a new, stable, green heptatwistacene (see structure). The molecule has a twist angle of 23.49°, is very stable even in air, and has an optical band gap of 1.82 eV.

Electroactive microbial biofilms and the microorganisms embedded therein are not only of crucial fundamental interest because they play an important role in redox cycles that occur in nature, they are also attracting increasing attention as key component of microbial bioelectrochemcial systems (BES). In these systems, interconversion of chemical and electrical energy and the associated exchange of electrons between living microbial cells and solid electrodes take place. The fascinating prospects and promise of BES technology have considerably increased the research on electroactive microbial biofilms over recent years. As a consequence, the research community is truly multifaceted, with backgrounds and interests ranging from molecular biology, via chemistry, to engineering. One of the most-important and most-widespread applied electrochemical techniques is cyclic voltammetry (CV). This Focus Review illustrates the power of this electrochemical technique and the versatility of the information that can be gained by its application for the electrochemical freshman. This Review will also pinpoint hurdles in using this technique, especially for the non-electrochemist, and the limitations of present models for data analysis. Because it aims to be a basic introduction, this Review will not discuss the latest intricacies in the field.

Cyclic voltammetry for biofilm freshmen: Electroactive microbial biofilms are attracting increasing attention from researchers from different disciplines. Cyclic voltammetry (CV) can be considered as a core technique for the study of these biofilms. This Focus Review aims to serve as a basic tutorial, especially for the electrochemical novice.

In the black: a chromic change of Pd-doped V₂O₅ nanowires from orange to black occurred after exposure to molecular hydrogen at room temperature. The change in color is irreversible and attributed to a hydrogen spillover effect.

5,10,15-Tris(pentafluorophenyl)tetrapyrromethane was efficiently prepared through a route involving stepwise diaroylation of 5-pentafluorophenyldipyrromethane. A₂B₆-type [36]octaphyrins were prepared by the cross condensation of the tetrapyrromethane with aryl aldehydes in moderate yields. A₂B₆-type [36]octaphyrins bearing 2,4,6-trifluorophenyl, 2,6-dichlorophenyl, and phenyl substituents underwent Cu^II-metalation-induced fragmentation to give two molecules of AB₃-type Cu^II porphyrins. A₂B₆-type [36]octaphyrin bearing 3-thienyl substituents underwent thermal N-thienyl fusion reactions to provide a modestly aromatic [38]octaphyrin, which, upon treatment with MnO₂, underwent further N-thienyl fusion and subsequent oxidation to give a nonaromatic doubly N-thienyl fused [36]octaphyrin.

Make ’em and break ’em: A₂B₆-type [36]octaphyrins were prepared in moderate yields by the cross condensation of tetrapyrromethane with aryl aldehydes. Compounds bearing 2,4,6-trifluorophenyl, 2,6-dichlorophenyl, and phenyl substituents underwent Cu^II-metalation-induced fragmentation to give AB₃-type Cu^II porphyrins, while that bearing a 3-thienyl substituent underwent N-thienyl fusion to provide a modestly aromatic [38]octaphyrin (see scheme).

Turn off: The interaction of enzyme substrate p-nitrophenyl α-D-N-acetylneuraminide (PNP-Neu5 Ac, see picture) with anionic conjugated polyelectrolytes is exploited in a new fluorometric approach for continuous and rapid assay of influenza-related sialidase activity and inhibition.

The synthesis of two formyl 2-tetrazenes, namely, (E)-1-formyl-1,4,4-trimethyl-2-tetrazene (2) and (E)-1,4-diformyl-1,4-dimethyl-2-tetrazene (3), by oxidation of (E)-1,1,4,4-tetramethyl-2-tetrazene (1) using potassium permanganate in acetone solution is presented. Compound 3 was also synthesized in an improved yield from the oxidation of 1-formyl-1-methylhydrazine (4 a) using potassium permanganate in acetone. Both compounds 2 and 3 were characterized by analytical (elemental analysis, GC-MS) and spectroscopic methods (¹H, ¹³C, and ¹⁵N NMR spectroscopy, and IR and Raman spectroscopy). In addition, the solid-state structures of the compounds were confirmed by low-temperature X-ray analysis. (Compound 2: triclinic; space group P-1; a=5.997(1) Å, b=8.714(1) Å, c=13.830(2) Å; α=107.35(1)°, β=90.53(1)°, γ=103.33(1)°; V_UC=668.9(2) ų; Z=4; ρ_calc=1.292 cm⁻³. Compound 3: monoclinic; space group P2₁/c; a=5.840(2) Å, b=7.414(3) Å, c=8.061(2) Å; β=100.75(3)°; V_UC=342(2) ų; Z=2; ρ_calc=1.396 g cm⁻³.) The vibrational frequencies of compounds 2 and 3 were calculated using the B3LYP method with a 6-311+G(d,p) basis set. We also computed the natural bond orbital (NBO) charges using the rMP2/aug-cc-pVDZ method and the heats of formation were determined on the basis of their electronic energies. Furthermore, the thermal stabilities of these compounds, as well as their sensitivity towards classical stimuli, were also assessed by differential scanning calorimetry and standard BAM tests, respectively. Lastly, the attempted synthesis of (E)-1,2,3,4-tetraformyl-2-tetrazene (6) is also discussed.

The synthesis and characterization of two formyl 2-tetrazenes (see Figure) is presented. These compounds may have applications as useful building blocks for the synthesis of materials with interesting energetic properties.

There’s a ringer: The asymmetric [4+2] cycloaddition reaction of 3-nitro-2H-chromenes with 1-benzyl-2-vinyl-1H-indoles catalyzed by Zn(OTf)₂ with bis(oxazoline) ligands offers a practical and efficient method to synthesize a variety of fused heterocycles bearing a quaternary stereocenter with good reaction efficiency (up to 94% yield) and excellent stereoselectivities (up to 96% ee, >95:5 d.r.).

3,4-Bis(1H-5-tetrazolyl)furoxan (H₂BTF, 2) and its monoanionic salts that contain nitrogen-rich cations were readily synthesized and fully characterized by multinuclear NMR (¹H, ¹³C) and IR spectroscopy, differential scanning calorimetry (DSC), and elemental analyses. Hydrazinium (3) and 4-amino-1,2,4-triazolium (7) salts crystallized in the monoclinic space group P2(1)/n and have calculated densities of 1.820 and 1.764 g cm⁻³, respectively. The densities of the energetic salts range between 1.63 and 1.79 g cm⁻³, as measured by a gas pycnometer. Detonation pressures and detonation velocities were calculated to be 23.1–32.5 GPa and 7740–8790 m s⁻¹, respectively.

Ready for an energy boost? Nitrogen-rich salts in which the anion bears a furoxan ring connected with two tetrazole rings exhibit reasonable physical properties, such as high densities (1.63–1.79 g cm⁻³) and good thermal stabilities (182–258 °C), and possess high positive heats of formation (859.8–1063.5 kJ mol⁻¹). Their detonation velocities and detonation pressures were calculated to be 7740–8790 m s⁻¹ and 23.1–32.5 GPa, respectively.

Bacillus subtilis can form a spore, which is a dormant type of cell, when its external environment becomes unsuitable for vegetative growth. The spore is surrounded by a multilayered proteinaceous shell called a spore coat, which plays a crucial role in dormancy and germination. Of the over 70 proteins that form the spore coat, only a small subset of them affect its morphogenesis; they are referred to as morphogenetic proteins. How these morphogenetic proteins interact, and furthermore, how they build the ordered, functional coat layers is not well understood. Elucidating the self-assembly mechanism of individual proteins into such a complex structure may contribute to its potential use in nano-biotechnology applications for preparing highly organized, robust, and resistant proteinaceous layers. Herein, direct, noncovalent, low-affinity interactions between the spore-coat morphogenetic proteins SpoIVA, SpoVID, and SafA were studied by using single-molecule recognition force spectroscopy in vitro for the first time. Based on the real-time examination of interactions between these three proteins, a series of dynamic kinetic data were obtained. It was also observed that the SafA–SpoVID interaction was stronger than that of SafA–SpoIVA.

Spontaneous spores: Spore-coat morphogenetic proteins are chemically bound to an AFM tip and silicon substrate, respectively, through a flexible cross-linker, and by using single-molecule recognition force spectroscopy (SMRFS) the piconewton forces and a series of dynamic kinetic data related to spore-coat morphogenetic proteins are obtained (see picture).

Doctor NO: Unprecedented β-carbon nitrosation of aliphatic tertiary amines on nitrosylruthenium complexes was revealed, where aerobic oxidative dehydrogenation of amines, CH bond activation, NC coupling, and enamine hydrolysis were involved.

A general palladium-catalyzed carbonylative dimerization of styrenes has been developed. Starting from commercial available styrenes, symmetrical 1,5-diarylpent-1-en-3-ones were produced in good to excellent yields (see scheme; dppp=1,3-bis(diphenylphosphino)propane).

Naphthol isomers, including α-naphthol (α-NAP) and β-naphthol (β-NAP), are used widely in various fields and are harmful to the environment and human health. The qualitative and quantitative determination of naphthol isomers is therefore of great significance. Herein, β-cyclodextrin (β-CD)-platinum nanoparticles (Pt NPs)/graphene nanosheets (GNs) nanohybrids (β-CD-PtNPs/GNs) were prepared for the first time using a simple wet chemical method and characterized by atomic force microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and electrochemical methods, and then applied successfully in the ultrasensitive electrochemical detection of naphthol isomers. The results show that the oxidation peak currents of naphthol isomers obtained at the glassy carbon (GC) electrode modified with β-CD-PtNPs/GNs are much higher than those at the β-CD/GNs/GC, PtNPs/GNs/GC, GNs/GC, and bare GC electrodes. Additionally, compared with other electrochemical sensors developed previously, the proposed electrode results in improved detection limits of about one order of magnitude for α-NAP (0.23 nM) and three orders of magnitude for β ‒NAP (0.37 nM).

A new hybrid unveiled: β-Cyclodextrin (β-CD)-platinum nanoparticles (Pt NPs)/graphene nanosheets (GNs) nanohybrids (β-CD-PtNPs/GNs) were prepared for the first time by a simple wet chemical method and used to detect naphthol isomers. Due to the excellent properties of GNs, Pt NPs, and β-CDs, electrodes modified with β-CD-PtNPs/GNs resulted in improved detection limits compared to the other electrochemical sensors developed for the detection of naphthol isomers.

Three novel 2,6-modified Bodipy sensitizers were synthesized and evaluated for their use in dye-sensitized solar cells (DSSCs). Among them, dye B3, which carries a n-pentyl group at position 8, exhibits the best solar energy conversion efficiency (1.83 %). The results of this study provide a new strategy for the design of Bodipy derivatives as sensitizers for DSSCs.

Heteroditopic hexahomotrioxacalix[3]arene receptors that are capable of binding an anion and a cation simultaneously in a cooperative fashion were synthesized. The structure of one of the triamide derivatives was confirmed by single-crystal X-ray diffraction. The binding of alkali metals at the lower rim, and the binding of anions (chloride, bromide) at the upper rim, has been investigated by using ¹H NMR titration experiments. Alkali metal binding at the lower rim controls the calix cavity. Li⁺-ion binding to the lower rim can improve the binding ability of anions at the upper rim amide moiety by a factor of 15, thus suggesting a strong positive allosteric effect for anion recognition. However, when a Na⁺ cation is bound to the ionophoric site on the lower rim, the calix cavity is changed from a “flattened cone” to a more-upright form, which is favored for intramolecular hydrogen bonding between the neighboring NH and CO groups; this change can block the inclusion of anions onto the amide moiety at the upper rim, which strongly suggests a negative allosteric effect of Na⁺-ion binding, which controls the cooperative recognition system.

Highs and lows: Hexahomotrioxacalix[3]arenes with triamide chains on their lower and upper rims simultaneously bind an anion and a cation. The binding of alkali metals at the lower rim and anions at the upper rim was investigated by using ¹H NMR titration experiments (see scheme; R=H, CH₃, F, CF₃; X=Cl, Br).

Hierarchical LiV₃O₈ nanofibers, assembled from nanosheets that have exposed {100} facets, have been fabricated by using electrospinning combined with calcination. The formation mechanism of hierarchical nanofibers was investigated by X-ray diffraction and scanning electron microscopy. Poly(vinyl alcohol) (PVA) played a dual role in the formation of the nanofibers: besides acting as the template for forming the fibers, it effectively prevented the aggregation of LiV₃O₈ nanoparticles, thereby allowing them to grow into small nanosheets with exposed {100} facets owing to the self-limitation property of LiV₃O₈. This nanostructure is beneficial for the insertion/extraction of lithium ions. Meanwhile, the {100} facets have fewer and smaller channels, which may effectively alleviate proton co-intercalation into the electrode materials. Hence, the hierarchical LiV₃O₈ nanofibers exhibit higher discharge capacities and better cycling stabilities as the anode electrode material for aqueous lithium-ion batteries than those reported previously. We demonstrate that these hierarchical nanofibers have promising potential applications in aqueous lithium-ion batteries.

Fruit and nanofiber: Hierarchical LiV₃O₈ nanofibers assembled from nanosheets with exposed {100} facets were fabricated by electrospinning combined with calcination. The nanofibers exhibit higher discharge capacity and better cycling stability as the anode electrode material for aqueous lithium-ion batteries. The cycling performance of the nanofibers is affected slightly by variation of the pH value in the electrolyte.

Three transition-metal–carbonyl complexes [V(L)(CO)₃(Cp)] (1), [Co(L)(CO)(Cp)] (2), and [Co(L₂)(CO)₃]⁺[CoCO)₄]⁻ (3), each containing stable N-heterocyclic-chlorosilylene ligands (L; L=PhC(NtBu)₂SiCl) were synthesized from [V(CO)₄(Cp)], [Co(CO)₂(Cp)], and Co₂(CO)₈, respectively. Complexes 1–3 were characterized by NMR and IR spectroscopy, EI-MS spectrometry, and elemental analysis. The molecular structures of compounds 1–3 were determined by single-crystal X-ray diffraction.

Three and easy: Three complexes [V(L)(CO)₃(Cp)], [Co(L)(CO)(Cp)], and [Co(L₂)(CO)₃]⁺[CoCO)₄]^- containing N-heterocyclic-chlorosilylene ligand L (L=PhC(NtBu)₂SiCl) were synthesized from [V(CO)₄(Cp)], [Co(CO)₂(Cp)], and Co₂(CO)₈, respectively.

Undergoing a radical change! The reduction of dibenzo[a,e]pentalene by KC₈ afforded the corresponding anion radical, the structure of which was characterized for the first time by X-ray diffraction analysis. The electronic state of the anion radical is discussed with the aid of theoretical calculations.

A good catch of CO₂! It is demonstrated for the first time that a high-surface-area, inorganic-based mesoporous silicon nitride prepared through a precipitation–sublimation route shows a high, reversible CO₂ uptake over a wide temperature range (298–423 K) with a moderate heat of adsorption. Our data render the thermally stable material a new contender for practical CO₂ capture.

It’s not in your DNA: We report here the synthesis of a novel 5-methyl deoxycytidine analog and its phosphoramidite modified with selenium at the C-5 position (^SeC). Incorporation of ^SeC into DNA does not cause structural perturbations, as shown by X-ray crystallography and in agreement with UV melting data. The Se modification provides a useful strategy for biochemical and structural investigations on 5-methylation of cytidine.

Carbon nanotubes (CNTs) have been widely considered as one of the promising candidates for replacing fluorine-doped tin oxide (FTO)/platinum (Pt) electrodes to reduce the fabrication cost of dye-sensitized solar cells (DSSCs). Here, we report that a bilayer transparent film containing N-doped CNTs (which are highly catalytic) and normal CNTs (which are highly conductive) as a counter electrode in DSSCs results in efficiencies up to 2.18 %, yet still maintains a good transparency with a transmittance of approximately 57 % at 550 nm.

A good case of doping! Carbon nanotubes (CNTs) have been widely considered as one of the promising candidates for replacing fluorine-doped tin oxide (FTO)/platinum (Pt) electrodes to reduce the fabrication cost of dye-sensitized solar cells (DSSCs). Here, we report that a bilayer transparent film containing N-doped CNTs and normal CNTs as a counter electrode in DSSCs results in efficiencies up to 2.18 %, yet still maintains a good transparency at 550 nm.

A mixture of bulk hexagonal boron nitride (h-BN) with hydrazine, 30 % H₂O₂, HNO₃/H₂SO₄, or oleum was heated in an autoclave at 100 °C to produce functionalized h-BN. The product formed stable colloid solutions in water (0.26–0.32 g L⁻¹) and N,N-dimethylformamide (0.34–0.52 g L⁻¹) upon mild ultrasonication. The yield of “soluble” h-BN reached about 70 wt %. The dispersions contained few-layered h-BN nanosheets with lateral dimensions in the order of several hundred nanometers. The functionalized dispersible h-BN was characterized by IR spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV/Vis spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). It is shown that h-BN preserves its hexagonal structure throughout the functionalization procedure. Its exfoliation into thin platelets upon contact with solvents is probably owing to the attachment of hydrophilic functionalities.

Divide and organize: Exfoliation and dispersion of hexagonal boron nitride (h-BN) was achieved through reaction with a range of inorganic reagents (see picture). The product exists in the form of stable colloids in water or N,N-dimethylformamide (DMF) as thin platelets of functionalized h-BN. Highlights of this method are high yields of soluble h-BN and increased concentrations of dispersions.

A couple of corrole–perylene carboximide dyads (C2-PIa and C2-PIx) have been synthesized and their photoreactivity has been evaluated. We aimed at obtaining better performances for photoinduced charge separation, both in terms of efficiency and in terms of lifetime, with respect to formerly studied systems. The energy level of the charge-separated state was tuned by selecting perylene and corrole components with diverse redox and spectroscopic properties. High spectroscopic energy levels of the perylene carboximide derivatives (PIs) allow a fast charge separation to be maintained in competition with an energy-transfer process from the PI to the corrole unit. Yields and lifetimes of charge separation in toluene are, respectively, 75 % and 2.5 μs for C2-PIa and 65 % and 24 ns for C2-PIx. The results and the effect of solvent polarity are discussed in the framework of current energy- and electron-transfer theories.

Let your light shine: Irradiation of corrole–perylene carboximide dyads can yield charge-separated states, which are crucial for the conversion of light energy to chemical energy (see picture). Tuning the redox properties and excited state energy of the electron donor gave optimized charge separation both in terms of yield and of lifetime.

A novel approach for creating efficient solid-state emitters is proposed. In this approach, various polyaromatic hydrocarbon groups are attached to tetraphenylethene, generating a series of luminogens that possess aggregation-induced emission characteristics. These luminogens are highly emissive in the solid state, with emission efficiencies equaling unity. High-performance OLEDs using these luminogens as light-emitting layers are fabricated, exhibiting efficiencies up to 5.6 lm W⁻¹, 7.3 cd A⁻¹, and 3.0 %.

Lipid-membrane-incorporating C₆₀ and C₇₀ (LMIC₆₀ and LMIC₇₀) were prepared by the fullerene-exchange reaction from the γ-cyclodextrin cavity to vesicles (we call this method the “exchange method”). An advantage of this method is that the ratios of [C₆₀]/[lipids] and [C₇₀]/[lipids] can be arbitrarily controlled by adjusting the ratios of the fullerenes and liposome. The maximum ratio (30 mol %) obtained was approximately 14 and 100 times higher than those achieved for LMIC₆₀ and LMIC₇₀, respectively, that were prepared by the classical method, which we call the “premixing method” (dissolving lipids and C₆₀ or C₇₀ in chloroform, followed by concentration and extraction with water). Furthermore, the stabilities and photodynamic activities of the LMIC₆₀ and LMIC₇₀ solutions prepared by the exchange method were shown to be much higher than those prepared by the premixing method. That is, the exchange method was found to be superior to the premixing method as a preparative method of LMIC₆₀ and LMIC₇₀ for applications in photomedical and photomaterials chemistry.

Method actors: Lipid-membrane-incorporated C₆₀ and C₇₀ (LMIC₆₀ and LMIC₇₀) were prepared by a fullerene-exchange reaction from the γ-cyclodextrin cavity to vesicles. Ratios of [C₆₀]/[lipids] (see figure) and [C₇₀]/[lipids] were arbitrarily controlled by adjusting the ratios of the fullerenes and liposome. The maximum ratio was higher than those for LMIC₆₀ and LMIC₇₀ prepared by the classical method.

A novel compound, 5,7,14,16-tetraphenyl-8:9,12:13-bisbenzo-hexatwistacene (TBH), has been successfully synthesized through a retro-Diels–Alder reaction. Single-crystal structure analysis indicated that TBH has a twisted configuration with a torsion angle of 27.34°. The HOMO–LUMO gap of TBH calculated from the difference between the half-wave redox potentials (E_1/2^ox=+0.40 eV and E_1/2^red=−1.78 eV) is 2.18 eV, which is in good agreement with the band gap (2.19 eV) derived from the UV/Vis absorption data. In addition, organic light-emitting devices using TBH as emitter have been fabricated. The results revealed that TBH is a promising red light-emitting candidate for applications in organic light-emitting diodes.

There is a twist: A novel compound, 5,7,14,16-tetraphenyl-8:9,12:13-bisbenzo-hexatwistacene (TBH), has been successfully synthesized. Single-crystal structure analysis indicated that TBH has a twisted configuration with a torsion angle of 27.34°. The electrochemical characteristics of TBH and data of fabricated organic light-emitting devices using TBH as emitter suggest that TBH is a promising red light-emitting candidate for applications in organic light-emitting diodes.

A series of organic dyes were prepared that displayed remarkable solar-to-energy conversion efficiencies in dye-sensitized solar cells (DSSCs). These dyes are composed of a 4-tert-butylphenylamine donor group (D), a cyanoacrylic-acid acceptor group (A), and a phenylene-thiophene-phenylene (PSP) spacer group, forming a D-π-A system. A dye containing a bulky tert-butylphenylene-substituted carbazole (CB) donor group showed the highest performance, with an overall conversion efficiency of 6.70 %. The performance of the device was correlated to the structural features of the donor groups; that is, the presence of a tert-butyl group can not only enhance the electron-donating ability of the donor, but can also suppress intermolecular aggregation. A typical device made with the CB-PSP dye afforded a maximum photon-to-current conversion efficiency (IPCE) of 80 % in the region 400–480 nm, a short-circuit photocurrent density J_sc=14.63 mA cm⁻², an open-circuit photovoltage V_oc=0.685 V, and a fill factor FF=0.67. When chenodeoxycholic acid (CDCA) was used as a co-absorbent, the open-circuit voltage of CB-PSP was elevated significantly, yet the overall performance decreased by 16–18 %. This result indicated that the presence of 4-tert-butylphenyl substituents can effectively inhibit self-aggregation, even without CDCA.

Quite materialistic: The dye CB-PSP exhibited J_sc (14.63 mA cm⁻²), V_oc (0.685 V), and FF values (0.67), which corresponded to a conversion efficiency of 6.70 %. The overall performance was reduced by about 16–18 % with addition of chenodeoxycholic acid (CDCA). This result indicated that the presence of tert-butylphenyl substituents can effectively inhibit self-aggregation, even without CDCA.

Fullerene–hydrazone dyads have been synthesized using the Confalone reaction followed by condensation with phenylhydrazines. Room-temperature xerographic time-of-flight, ionization potential, and cyclic voltammetry measurements indicate that these narrow-band-gap (E_g<1.5 eV), ambipolar charge-transporting dyads with balanced hole- and electron mobilities, which operate in air, are attractive materials for various optoelectronic applications.

Mind the gap: A group of fullerene–hydrazone dyads have been synthesized. Room-temperature xerographic time-of-flight, ionization potential, and cyclic voltammetry measurements indicate that these narrow-band-gap (E_g<1.5 eV), ambipolar charge-transporting dyads with balanced hole- and electron mobilities are attractive materials for various optoelectronic applications.

The total synthesis of (+)-asteriscanolide is reported. The synthetic route features two key reactions: 1) the rhodium(I)-catalyzed [(5+2)+1] cycloaddition of a chiral ene-vinylcyclopropane (ene-VCP) substrate to construct the [6.3.0] carbocyclic core with excellent asymmetric induction, and 2) an alkoxycarbonyl-radical cyclization that builds the bridging butyrolactone ring with high efficiency. Other features of this synthetic route include the catalytic asymmetric alkynylation of an aldehyde to synthesize the chiral ene-VCP substrate, a highly regioselective conversion of the [(5+2)+1] cycloadduct into its enol triflate, and the inversion of the inside–outside tricycle to the outside–outside structure by an ester-reduction/elimination to enol-ether/hydrogenation procedure. In addition, density functional theory (DFT) rationalization of the chiral induction of the [(5+2)+1] reaction and the diastereoselectivity of the radical annulation has been presented. Equally important is that we have also developed other routes to synthesize asteriscanolide using the rhodium(I)-catalyzed [(5+2)+1] cycloaddition as the key step. Even though these routes failed to achieve the total synthesis, these experiments gave further useful information about the scope of the [(5+2)+1] reaction and paved the way for its future application in synthesis.

Asterisc and reward: The total synthesis of (+)-asteriscanolide features two key reactions: rhodium(I)-catalyzed [(5+2)+1] cycloaddition to construct the [6.3.0] carbocyclic core and alkoxycarbonyl radical annulation to build the butyrolactone ring.

Modern computer processors are based on semiconductor logic gates connected to each other in complex circuits. This study contributes to the development of a new class of connectable logic gates made of DNA in which the transfer of oligonucleotide fragments as input/output signals occurs upon hybridization of DNA sequences. The DNA strands responsible for a logic function form associates containing immobile DNA four-way junction structures when the signal is high and dissociate into separate strands when the signal is low. A basic set of logic gates (NOT, AND, and OR) was designed. Two NOT gates, two AND gates, and an OR gate were connected in a network that corresponds to an XOR logic function. The design of the logic gates presented here may contribute to the development of the first biocompatible molecular computer.

Future computer? This study contributes to the development of a new class of connectable logic gates made of DNA in which the transfer of oligonucleotide fragments as input/output signals occurs upon hybridization of DNA sequences. A basic set of DNA logic gates was designed and connected in a network that corresponds to an XOR logic function (see figure).

o-C₆H₄(SiR_3−nH_n)(BMes₂) (1; R=Me, Ph; n=1, 2) undergo MesH (Mes=mesityl) ligand exchange between the silicon atom and the boron atom to form o-C₆H₄(SiMesR_3−nH_n−1)(BMesH) (6) upon heating. The resulting hydroborane intermediates (6) immediately react with benzaldehyde to afford their corresponding benzyloxyboranes (5). A DFT study of model compounds reveals the transition states of the ligand exchange. A hydride abstraction from the silicon atom by the boron center is key to reaching the transition states, which include the tricoordinate silyl-cation moiety and the tetracoordinate hydridoborate moiety.

A HArd days night: HAr ligand exchange between Si and B atoms occurs on heating o-(hydrosilyl)(diarylboryl)benzenes. Hydroborane intermediates react with benzaldehyde to afford benzyloxyboranes. Hydride abstraction is key to reaching the transition states.

Biomimetic fabrication is promising for functionalizing artificial materials with special properties learned from nature; superhydrophobicity is a typical example. However, a superhydrophibic graphene surface created by micro/nanostructuring has not been reported yet. As described in their Communication on page 301 ff., Y. L. Zhang, H. B. Sun et al. present biomimetic graphene surfaces with both superhydrophobicity and bright structural color. The method is so simple that hierarchical micro/nanostructures and the modulation of surface chemical composition were realized synchronously by using two-beam laser interference. The results obtained in this study demonstrate a facile approach to wettability control of graphene.

Fluorogenic protein labeling helps to localize a protein within the cell in the presence of an excess amount of quenched probes. In their Communication on page 272 ff., K. Kikuchi et al. propose an alternative fast approach for fluorogenic protein labeling. The fluorogenicity can be introduced by the removal of a photoinduced electron transfer-based dynamic quencher. This strategy is more effective compared to the removal of a static aggregated quencher. The cover picture illustrates the better visibility of fireworks at the dynamic state (photo taken at the Hanabi festival in Japan; Sujata Kar Saha helped with cover design).

Mass spectrometry both complements other analytical techniques and allows for types of analyses and experiments not possible with common analytical methods, such as NMR, IR, and UV/Vis spectroscopy. Electrospray constitutes one of the mildest forms of ionization, making it the preferred method for the analysis of large fragile or reactive ions. There is particular promise for mass spectrometry in aiding the characterization of polyoxometalates and their solutions, but caution must be taken in designing the experiments in order to yield reliable data and to avoid the temptation of over-interpreting the relevance of gas-phase data to solution chemistry.

In the spray: Electrospray ionization mass spectrometry has the potential of providing otherwise inaccessible information about the chemistry of polyoxometalates. This Focus Review introduces the concept of electrospray ionization mass spectrometry, gives an overview of examples in the literature of its application to the study of polyoxometalates, and discusses the strengths and limitations of the method in the investigation of reaction dynamics and speciation.

Keeping quenchers on a short leash: Shortening of the linker chain length combined with modification of the quencher moiety was found to improve fluorogenic probes useful for protein labeling by the mutant β-lactamase-tag (BL-tag) technology. The most effective probe, CC3 DNB, displays fluorescence quenching by photoinduced electron transfer (PET) and results in fluorescent protein labeling with fast kinetics.

Stuck on you: Amine-, oxyamine-, and isocyanate-terminated self-assembled monolayers were deposited on silicon wafers for reaction with cobaltabisdicarbollide derivatives. The reaction of the isocyanate group with [NMe₄][8-NH₂-C₄H₈O₂-3,3-Co(1,2-C₂B₉H₁₀)(1,2-C₂B₉H₁₁)] gave homogeneous monolayers of cobaltabisdicarbollide moieties covalently linked to the surface (see picture).

Do the coupling: A palladium-catalyzed oxidative carbonylative coupling process of arylboronic acid with styrenes to chalcone has been developed. The reactions proceed under mild conditions using air as the terminal oxidant reagent.

Nanoparticles meet nanotubes! Direct synthesis of TiN nanoparticles in a three-dimensional network of few-walled carbon nanotubes (FWCNTs) was achieved by using mesoporous graphitic carbon nitride (C₃N₄) as both a hard template and a nitrogen source. The TiN/FWCNT composite showed high performance for the oxygen reduction reaction in acidic media.

The most stable IPR isomer of C₈₈ fullerene, C₈₈ (17), has been captured by chlorination as C₈₈(17)Cl₁₆ and C₈₈(17)Cl₂₂. X-ray crystallography revealed C_s-symmetrical molecular structures of both compounds, with the former being a substructure of the latter (see picture; C grey, Cl green). The chlorination patterns are characterized by the formation of isolated double CC bonds, benzenoid rings, and, in C₈₈(17)Cl₂₂, a long chain of Cl additions in adjacent positions on the C₈₈ fullerene cage.

One thing leads to another: A novel palladium(II)-catalyzed three-component domino reaction of diyne-enones with nucleophiles and vinyl ketones or acrolein under mild conditions provides efficient, general, and atom-economical access to multifunctionalized 2,3-cyclo[b]furan with a stereodefined tri- or tetrasubstituted olefin.

Instant silylene! LiBr assists the dissociation of 1,2-diaryl-1,2-dibromodisilenes. Reactions with various trapping agents gave products identical to those from corresponding reactions with aryl bromosilylenes. The reaction provides a method for the in situ generation of silylenes under mild conditions, and the reaction rate is increased by the addition of LiBr.

The wonderful world of graphene! A simple one-step fabrication of biomimetic graphene surfaces that possess both superhydrophobicity and bright structural color is presented. By using two-beam laser interference, construction of periodic grating microstructures and removal of hydrophilic oxygen groups were realized at the same time.

A convenient method for the synthesis of highly substituted isoquinolines and isoquinolinium salts by the nickel-catalyzed cyclization of ortho-haloketoximes and -ketimines, respectively, with alkynes is described. The reaction of ortho-haloketoximes and various alkynes in the presence of [Ni(PPh₃)₂Br₂] and zinc powder in a mixture of acetonitrile and tetrahydrofuran at 80 °C for 15 hours gave 1,3,4-trisubstituted isoquinoline products in moderate to excellent yields and high regioselectivity. The corresponding isoquinoline N-oxide was found to be the intermediate in the cyclization reaction pathway. In contrast, the reaction of ortho-haloketimines and alkynes under similar catalytic conditions in tetrahydrofuran at 70 °C for two hours gave 1,2,3,4-tetrasubstituted isoquinolinium salts in good to excellent yields.

In the nickel of time: ortho-Haloketoximes and -ketimines undergo [4+2] cyclization reactions with alkynes, catalyzed by nickel complexes to give highly substituted isoquinolines and isoquinolinium salts, respectively, in good to excellent yields (see scheme).

The combination of ZnEt₂ and chiral pyridinebisoxazoline (pybox) or pyridinebisimidazoline (pybim) ligands catalyzed the asymmetric hydrosilylation of aryl, alkyl, cyclic, heterocyclic, and aliphatic ketones. Under mild conditions, high yields and good enantioselectivities were achieved. ESI measurements allowed for the characterization of the active catalyst.

Zincing outside of the pybox: A ZnEt₂/pybox catalyst promotes the hydrosilylation of carbonyl compounds under mild conditions to afford high yields and good ee values for a broad range of aryl, alkyl, cyclic, heterocyclic, and aliphatic ketones.

A series of deoxycholic and cholic acid-derived oligomers were synthesized and their ability to extract hydrophilic dye molecules of different structure, size, and functional groups into nonpolar media was studied. The structure of the dye and “dendritic effect” in the extraction process was examined using absorption spectroscopy and dynamic light scattering (DLS). The efficiency of structurally preorganized oligomers in the aggregation process was evaluated by 1-anilinonaphthalene-8-sulfonic acid (ANS) fluorescence studies. The possible formation of globular structures for higher-generation molecules was investigated by molecular modeling studies and the results were correlated with the anomaly observed in the extraction process with this molecule. The ability of these molecules for selective extraction of specific dyes from blended colors is also reported.

Solubilizing insoluble dyes! A new series of cholic acid-derived dendritic structures were synthesized and their aggregation in chloroform was studied. These aggregates were used as nanocarriers for hydrophilic dye molecules in chloroform. The influence of chiral aggregates on the chiroptical properties of the dye was studied by induced circular dichroism. Finally, these molecules were investigated for selective extraction of one dye from a blended food color.

The crystal polymorphism of the anthelmintic drug, triclabendazole (TCB), is described. Two anhydrates (Forms I and II), three solvates, and an amorphous form have been previously mentioned. This study reports the crystal structures of Forms I (1) and II (2). These structures illustrate the uncommon phenomenon of tautomeric polymorphism. TCB exists as two tautomers A and B. Form I (Z′=2) is composed of two molecules of tautomer A while Form II (Z′=1) contains a 1:1 mixture of A and B. The polymorphs are also characterized by using other solid-state techniques (differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), PXRD, FT-IR, and NMR spectroscopy). Form I is the higher melting form (m.p.: 177 °C, ΔH_f=≈105±4 J g⁻¹) and is the more stable form at room temperature. Form II is the lower melting polymorph (m.p.: 166 °C, ΔH_f=≈86±3 J g⁻¹) and shows high kinetic stability on storage in comparison to the amorphous form but it transforms readily into Form I in a solution-mediated process. Crystal structure analysis of co-crystals 3–11 further confirms the existence of tautomeric polymorphism in TCB. In 3 and 11, tautomer A is present whereas in 4–10 the TCB molecule exists wholly as tautomer B. The DFT calculations suggest that the optimized tautomers A and B have nearly the same energies. Single point energy calculations reveal that tautomer A (in Form I) exists in two low-energy conformations, whereas in Form II both tautomers A and B exist in an unfavorable high-energy conformation, stabilized by a five-point dimer synthon. The structural and thermodynamic features of 1–11 are discussed in detail. Triclabendazole is an intriguing case in which tautomeric and conformational variations co-exist in the polymorphs.

The crystal structures of polymorphs, co-crystals, and salts of the anthelmintic drug triclabendazole are discussed in the context of an uncommon variety of polymorphism, namely, tautomeric polymorphism.

We have synthesized and characterized four organic dyes (H1–H4) based on a 3,6-disubstituted carbazole donor as sensitizers in dye-sensitized solar cells. These dyes have high molar extinction coefficients and energy levels suitable for electron transfer from an electrolyte to nanocrystalline TiO₂ particles. Under standard air mass 1.5 global (AM 1.5 G) solar irradiation, a device using dye H4 exhibits a short-circuit current density (J_sc) of 13.7 mA cm⁻², an open-circuit voltage (V_oc) of 0.68 V, a fill factor (FF) of 0.70, and a calculated efficiency of 6.52 %. This performance is comparable to that of a reference cell based on N719 (7.30 %) under the same conditions. After 1000 hours of visible-light soaking at 60 °C, the overall efficiency remained at 95 % of the initial value.

Metal-free sensitizer: Four organic dyes based on a 3,6-disubstituted carbazole donor have been synthesized for their potential use as sensitizers in dye-sensitized solar cells. These dyes have high molar extinction coefficients and energy levels suitable for electron transfer from an electrolyte to nanocrystalline TiO₂ particles. Under standard global AM 1.5 solar irradiation, a device using one of the prepared dyes (see graphic) exhibited a calculated efficiency of 6.52 %.

A new triarylphosphine–tertiary amine bifunctional polymeric reagent has been prepared and used effectively in a variety of one-pot Wittig reactions. The design of this reagent resolved a deficiency of a previously reported related material, and allowed it to perform more efficiently in such reactions. Furthermore, it was readily recyclable, and was also successfully applied in cascade processes involving one-pot Wittig reactions followed by either a conjugate reduction or a reductive aldol reaction. In these reaction cascades, the phosphine oxide groups generated in the Wittig reaction served as the catalyst for the subsequent reaction.

All in one pot! A recyclable, second-generation heterogeneous bifunctional polymer bearing phosphine and amine groups has been synthesized and showed enhanced utility in one-pot Wittig reactions compared to a previously reported related material. This polymer was also used in Wittig reaction cascade processes in which the oxidized polymer formed in the one-pot Wittig reaction served as the catalyst in a subsequent conjugate reduction or reductive aldol reaction (see scheme).

The solid-state chiral optical properties (circular dichroism and circularly polarized luminescence) of a 2-naphthalenecarboxylic acid/amine supramolecular organic fluorophore can be controlled by changing the aryl unit of the chiral 1-arylethylamine component of the molecule rather than altering the chirality of the 1-arylethylamine itself.

Predisposed to glow: The solid-state circular dichroism and circularly polarized luminescence of a 2-naphthalenecarboxylic acid/amine supramolecular organic fluorophore can be controlled by changing the aryl unit of the chiral 1-arylethylamine component rather than changing the chirality of the 1-arylethylamine itself (see picture).

Mild substitution reactions of acetals with carbon nucleophiles via the pyridinium-type salts generated by the treatment of acetals with TESOTf-2,4,6-collidine or 2,2′-bipyridyl have been developed. Various carbon nucleophiles, such as organocuprates, silyl enol ethers, enamines, etc., reacted with the pyridinium-type salts to give the corresponding substituted products in good yields. The reactions proceeded under very mild conditions (non-acidic conditions) and thus acid-sensitive functional groups can be tolerated during the reaction. In addition, only an acetal can form the pyridinium-type salt and react with nucleophiles in the presence of a ketal. This unusual selectivity is in contrast to general methods conducted under acidic conditions.

Salty but sweet: Pyridinium-type salts generated from acetals are effective electrophiles for various carbon nucleophiles. The reactions proceed under very mild (non-acidic) reaction conditions and can tolerate acid-sensitive functional groups (see scheme).

2-(2-Hydroxy-phenyl)-4(3H)-quinazolinone (HPQ), an organic fluorescent material that exhibits fluorescence by the excited-state intramolecular proton-transfer (ESIPT) mechanism, forms two different polymorphs in tetrahydrofuran. The conformational twist between the phenyl and quinazolinone rings of HPQ leads to different molecular packing in the solid state, giving structures that show solid-state fluorescence at 497 and 511 nm. HPQ also shows intense fluorescence in dimethyl formamide (DMF) solution and selectively detects Zn²⁺ and Cd²⁺ ions at micromolar concentrations in DMF. Importantly, HPQ not only detects Zn²⁺ and Cd²⁺ ions selectively, but it also distinguishes between the metal ions with a fluorescence λ_max that is blue-shifted from 497 to 420 and 426 nm for Zn²⁺ and Cd²⁺ ions, respectively. Hence, tunable solid-state fluorescence and selective metal-ion-sensor properties were demonstrated in a single organic material.

Fluorescence chameleon: The title compound HPQ (see picture) displays fluorescence in the solid state and in solution. Recrystallization from THF yields polymorphs that show differently colored fluorescence (right). In DMF solution, the strong fluorescence of HPQ is selectively blue-shifted upon addition of Zn²⁺ and Cd²⁺ ions (left).

The oxidation of 1,5-dimethyl-3-(2′-pyridyl)-6-thiooxotetrazane (SvdH₃py) by benzoquinone leads to a 1:1 adduct of 1,5-dimethyl-3-(2′-pyridyl)-6-thiooxoverdazyl radical (Svdpy) with hydroquinone (hq). The single-crystal X-ray diffraction of this adduct at room temperature (RT) shows that the radicals exhibit a slight curvature that leads to the formation of alternating head-to-tail (antiparallel) stacked 1D chains. Moreover, temperature-dependent X-ray measurements at 100, 200, and 303 K reveal that the lateral slippages between the radicals of the stacks |δ₁| and |δ₂| vary from 0.64 to 0.78 Å and 0.54 to 0.40 Å between 100 and 303 K. Despite the alternation of the inter-radical distances and lateral slippages, the magnetic susceptibility data can be fitted with excellent agreement using a regular one-dimensional antiferromagnetic chain model with J=−5.9 cm⁻¹. Wavefunction-based calculations indicate an alternation of the magnetic interaction parameters correlated with the structural analysis at RT. Moreover, they demonstrate that the thermal slippage of the radicals induces a switching of the physical behavior, since the exchange interaction changes from antiferromagnetic (−0.9 cm⁻¹) at 100 K to ferromagnetic (1.4 cm⁻¹) at 303 K. The theoretical approach thus reveals a much richer magnetic behavior than the analysis of the magnetic susceptibility data and ultimately questions the relevance of a spin-coupled picture based on temperature-independent parameters.

When temperature does matter: The mismatch between the crystal structure of a thioverdazyl adduct and the apparent S=1/2 one-dimensional antiferromagnetic behavior of the magnetic susceptibility is analyzed with ab initio methods. In such organic-radical-based materials, the underlying magnetic behavior is shown to be much more subtle.

An enhancement in catalytic alcohol oxidation activity is attributed to the presence of nitrogen heteroatoms on the external surface of a support material. The same Pd particles (3.1–3.2 nm) were supported on polymeric carbon–nitrogen supports and used as catalysts to selectively oxidize benzyl alcohol. The polymeric carbon–nitrogen materials include covalent triazine frameworks (CTF) and carbon nitride (C₃N₄) materials with nitrogen content varying from 9 to 58 atomic percent. With comparable metal exposure, estimated by X-ray photoelectron spectroscopy, the activity of these catalysts correlates with the concentration of nitrogen species on the surface. Because the catalysts showed comparable acidic/basic properties, this enhancement cannot be ascribed to the Lewis basicity but most probably to the nature of N-containing groups that govern the adsorption sites of the Pd nanoparticles.

Anchor it and speed it up! An enhancement in catalytic alcohol oxidation activity (see figure) is attributed to the presence of nitrogen heteroatoms on the external surface of a support material, which direct adsorption of Pd nanoparticles.

The self-assembled structure of alkoxy- and N-alkylcarbamoyl-substituted zinc–tetraphenylporphyrin at the liquid–highly oriented pyrolytic graphite (HOPG) interface was observed by using scanning tunneling microscopy. The alkoxy porphyrin showed a phase transition from face-on to edge-on ordering. The phase transition requires the close-packed structure of alkoxy porphyrin. The chronological change of the ordering was traced to show the existence of several types of Ostwald ripening including two-step phase transition from small edge-on to face-on and then further to edge-on orderings. On the other hand, the N-alkylcarbamoyl porphyrin showed persistent edge-on ordering, and the ordering was analyzed by the Moiré pattern. Although the edge-on ordering is observed only in the nonpolar solvent, the orderings have potential applications in the charge and energy transfer.

Following orders: The self-assembled structure of alkoxy- and N-alkylcarbamoyl-substituted zinc–tetraphenylporphyrin at the liquid–highly oriented pyrolytic graphite (HOPG) interface was observed using scanning tunneling microscopy. The alkoxy porphyrin showed phase transition from face-on to edge-on ordering, whereas the N-alkylcarbamoyl porphyrin showed persistent edge-on ordering (see figure).

A dynamic combinatorial library of lanthanide complexes was prepared to develop induced-circular-dichroism (CD) chirality probes. It totaled 168 combinations of coordinative N-aromatic chromophores, trivalent lanthanide centers, and guest amino acids. Eu³⁺ and Tb³⁺ complexes prepared with quinolinecarboxylic acid were particularly effective as induced-CD chirality probes for selective alanine detection, whereas a Yb³⁺ complex with terpyridine exhibited glutamine selectivity. The former two complexes highly preferred alanine to the corresponding amine, ester, amino alcohol, and carboxylic acid derivatives. As such, the present combinatorial screening of a dynamic lanthanide complex library has led to a new series of induced-CD chirality probes for specific amino acids.

Mix and match: A dynamic combinatorial library of lanthanide complexes was prepared to develop induced-circular-dichroism (CD) chirality probes. It totaled 168 combinations of coordinative N-aromatic chromophores, trivalent lanthanide centers, and guest amino acids. Combinatorial screening led to a new series of induced-CD chirality probes for specific amino acids (see graphic).

We report unconventional magnetotransport properties of an individual Fe_1−xCo_xSi nanowire. We have studied the dependence of the resistivity on the angle between the directions of the magnetization and electrical current below the Curie temperature (T_C). The observed anisotropic magnetoresistance (MR) ratio is negative, thereby indicating that the conduction electrons in a minority spin band of the Fe_1−xCo_xSi nanowire dominantly contribute to the transport. Unlike typical ferromagnets, positive MR is observed in the overall temperature range. MR curves are linear below T_C and show a quadratic form above T_C, which can be explained by the change of density of states that arises as the band structures of the Fe_1−xCo_xSi nanowire shift under a magnetic field. The temperature dependence of the resistivity curve is sufficiently explained by the Kondo effect. The Kondo temperature of the Fe_1−xCo_xSi nanowire is lower than that of the bulk state due to suppression of the Kondo effect. The high single crystallinity of Fe_1−xCo_xSi nanowires allowed us to observe and interpret quite subtle variations in the prominent intrinsic transport properties.

Down to the wire: Ferromagnetic single-crystalline Fe_1−xCo_xSi nanowires (NWs) were synthesized by means of a vapor transport method with no catalyst. The magnetotransport properties of the Fe_1−xCo_xSi NW reveal negative anisotropic magnetoresistance owing to dominant spin-down electrons. The various results (see figure) are of interest for spintronic devices.

Nanoporous carbon materials are highly important materials for a wide array of applications. Here we show that nanoporous carbon can act as highly active materials for electrochemical sensing. We observed that nanoporous carbon material exhibits a faster heterogeneous electron transfer than graphite and pure carbon nanotubes. Nanoporous carbon exhibits a superior electrochemical performance for sensing of important biomarkers such as dopamine, ascorbic acid, uric acid, NADH, DNA bases, and forensic-related compounds such as nitroaromatic explosives.

Nanoporezní materiály na bázi uhlíku nacházejí využití v mnoha oblastech. V tomto článku ukážeme jejich výhody pro použití v oblasti electrochemického stanovení látek. Heterogenní přenos elektronu mezi nanoporézním uhlíkem a solutem je velmi rychlý. Použití tohoto typu uhlíku je velmi výhodné pro stanovení dopaminu, vitamínu C, kyseliny močové, NADH, DNA bází a nitroaromatických látek.

A great sense of achievement! The performance of nanoporous carbon as an electrode material was investigated and compared with that of bare glassy carbon, graphite microparticles, and carbon nanotubes. Nanoporous carbon was found to exhibit the highest heterogeneous electron transfer (HET) rate among these materials, thus sensing analytes such as NADH, DNA bases, and 2,4,6-trinitrotoluene (TNT) with an improved electrochemical response.

We describe a shape-controlled synthesis of polyelectrolyte-functionalized flowerlike and polyhedral Au nanoparticles and the development of a nanoarchitectured platform for the selective and highly sensitive detection of protamine and heparin by voltammetric, impedimetric, and microgravimetric techniques. The functionalized Au nanoparticles were chemically synthesized in aqueous solution at room temperature in the presence of the polyelectrolyte (either protamine or heparin). The charge on the polyelectrolyte controlled the shape and surface morphology of the nanoparticles. The negatively charged heparin-functionalized Au nanoparticles have multiple branched flowerlike shapes with an average size of 50 nm, whereas the cationic protamine-functionalized nanoparticles are of polyhedral shape with an average size of 25 nm. Both flowerlike and polyhedral nanoparticles have (111), (200), (220), and (311) planes of a face-centered cubic lattice of Au. Voltammetric, impedimetric, and microgravimetric sensing platforms based on functionalized Au nanoparticles have been developed for the sensing of heparin and protamine. The sensing platforms are developed by self-assembling the functionalized nanoparticles on a thiol-functionalized three-dimensional silicate network. The microgravimetric sensing platform shows very high sensitivity and it can detect heparin and protamine at concentrations as low as 0.05 μg mL⁻¹. The selectivity of the sensing platform towards heparin was examined with potential interferents such as hyaluronic acid (HA) and chondroitin-4-sulfate (CS). Both HA and CS did not interfere with the measurement of heparin. The practical application of the sensing platform was demonstrated by measuring the concentration of heparin and protamine in human serum samples. The sensing platform could successfully quantify the concentration of heparin and protamine in the real serum samples with excellent recovery. The sensing platform was robust and could be used for repeated measurement without compromising the sensitivity.

Drug sniffer: A highly sensitive nanoarchitectured platform based on a functionalized Au nanoparticle scaffold for the sensing of biomedically important polyionic drugs has been developed (see scheme).

As potential inhibitors of penicillin-binding proteins (PBPs), we focused our research on the synthesis of non-traditional 1,3-bridged β-lactams embedded into macrocycles. We synthesized 12- to 22-membered bicyclic β-lactams by the ring-closing metathesis (RCM) of bis-ω-alkenyl-3(S)-aminoazetidinone precursors. The reactivity of 1,3-bridged β-lactams was estimated by the determination of the energy barrier of a concerted nucleophilic attack and lactam ring-opening process by using ab initio calculations. The results predicted that 16-membered cycles should be more reactive. Biochemical evaluations against R39 DD-peptidase and two resistant PBPs, namely, PBP2a and PBP5, revealed the inhibition effect of compound 4 d, which featured a 16-membered bridge and the N-tert-butyloxycarbonyl chain at the C3 position of the β-lactam ring. Surprisingly, the corresponding bicycle, 12 d, with the PhOCH₂CO side chain at C3 was inactive. Reaction models of the R39 active site gave a new insight into the geometric requirements of the conformation of potential ligands and their steric hindrance; this could help in the design of new compounds.

Bridging inhibition: A series of 12- to 22-membered bicyclic bridged β-lactams were synthesized with the aim of developing new inhibitors of penicillin-binding proteins and feature a planar amide function and no carboxy group (see picture; Boc=tert-butyloxycarbonyl).