ChemPhysChem

The cover picture shows a biological supercapacitor developed from the redox reactions of c-type cytochromes embedded in biofilms of a common soil microorganism Geobacter sulfurreducens. On p. 463 N. S. Malvankar et al. report this first demonstration of a living, self-renewing supercapacitor using a combination of in situ electrochemistry, protein engineering and denaturing, as well as capacitance modeling. The superior electrochemical performance of the biofilm supercapacitor is due to its high abundance of cytochromes, providing large electron storage capacity, its network of protein nanowires with metallic-like conductivity, and its porous architecture with hydrous nature that maintains electroneutrality, offering prospects for future low-cost and environmentally sustainable energy storage devices.

The adsorption of acetylene on CPO-27-M (MFe, Co and Ni) frameworks is studied by FTIR and UV/Vis spectroscopy, as well as calorimetric isotherm measurements, as shown on p. 445 by S. M. Chavan et al. MO pairs act as the adsorption sites in these materials and the Ni analogue is the strongest acetylene adsorbent of the series.

Light on photosynthesis: Theoretical studies relevant to the excited-state processes in the early stages of photosynthesis, such as absorption, light harvesting, photoprotection, and energy transfer, are reviewed (see picture). Methodological aspects of excited-state electronic-structure methods and studies on (bacterio)chlorophylls and carotenoids are discussed. The concepts of exciton coupling and excitation-energy transfer are addressed.

How tintinnabulary! Optical resonator biosensors are emerging as one of the most sensitive microsystem biodetection technology that does not require amplification or labeling of the analyte (see graphic). This minireview provides a scholarly introduction to this research area and reviews current advances in molecular diagnostics and nanoparticle detection.

Probing atoms: An overview of high-resolution scanning transmission electron microscopy (HRSTEM) techniques is given (see picture). Current advances suggest that HRSTEM-related techniques are fundamental tools for comprehensive assessment of properties at the atomic scale.

MOFs as acetylene adsorbents: The adsorption of acetylene on the isostructural metal–organic frameworks CPO-27-M (where M=Fe, Co and Ni) is studied by FTIR, UV/Vis spectroscopy, and calorimetric isotherm measurements. The results show that M–O pairs act as the adsorption sites in these materials and that the Ni analogue is the strongest acetylene adsorbent of the series.

Endohedral metallofullerenes: Density functional theory studies reveal that the smallest gadolinium nitride cluster fullerene, Gd₃N@C₂(22010)C₇₈, not only possesses a high kinetic stability but also a high thermodynamic stability. Further investigations on the electronic structure, properties and IR vibrational frequencies expose the important covalent interaction between the metal cluster and the carbon cage.

New moiety for drug design: The chemical group squaramide shows promising results in medicinal chemistry. The mechanism of action of cyclic oligosquaramides at biological membranes is revealed by a monolayer study. The biological activity is related to the hydrophobicity of the new squaramide-derivative drugs.

Where you want it, when you want it: When cleaved in vacuum, a semiconductor exposes a highly reactive surface that can be exploited to obtain well controlled chemical bonds. Now, using sacrificial microstructures and a 2+2 cycloaddition process, organic molecules are covalently bound to a silicon pre-patterned surface in liquid environment with accurate spatial control (see picture).

Living supercapacitors: The capacitance of an electrode-based device can be enhanced 100-fold using the redox chemistry of c-type cytochromes naturally embedded in an electrically conductive network of living bacteria (see picture). This study demonstrates the unique survival strategy by metal-respiring bacteria when electron acceptors are temporarily unavailable and suggests a novel method for supercapacitive energy storage using self-renewing microbes.

Ultracold chemistry in helium droplets: The electron ionization of helium droplets doped with methane clusters is investigated for the first time using high-resolution mass spectrometry (see picture). The mass spectra show clear evidence for magic numbers, which are broadly consistent with icosahedral shell closings.

Dynamic gratings: A transient grating created by the interference of laser pulses (see picture) is shown to be of use to study ultrafast processes in sub-nanometer films under ambient conditions. The technique is sensitive enough to investigate the dynamics in systems, where only 20 % of the surface is covered by nanocrystals.

Positive feedback: The precessing magnetizations of the two species M_a and M_b can influence each other through the feedback field of the detection circuit (radiation damping field, see picture). The resulting spectra exhibit surprising line shapes, such as the appearance of a hole, allowing detection of hidden tiny signals.

In the frame: The adsorption enthalpy of CO in metal–organic framework CuBTC material is investigated. The reliability of various methods for the description of CO interaction with the Cu²⁺ site in CuBTC is discussed based on experimental results and accurate coupled-cluster calculations of the paddle wheel (see picture).

Stronger than you think: A theoretical study of the HTeXH (X=O, S, Se and Te) monomers and homodimers is carried out by means of MP2 computational methods. Hydrogen bonds and chalcogen–chalcogen interactions are characterized and their influence analyzed concerning the stability and chiral discrimination of the dimers (see picture).

The long and short of it: Spontaneous ionization of N-alkylphenothiazines (alkyl-PTZ) is observed upon sorption on three channel-type acid zeolites (ferrierite, MFI, and mordenite; see picture). Diffuse reflectance UV–visible absorption and Raman scattering data reveal the major role of the confinement effect in the redox behavior and demonstrate the flexibility of the alkyl chain.

Surprisingly conductive: Pure water in charged porous matrices is found to be moderately conductive. Experiments (circles) and calculations (solid line) show that this effect is caused by the electric double layer established at the solid/water interfaces, and that the ionic conductivity of water κ_w can reach the order of 10⁻³ S cm⁻¹ (see picture). This finding may help to understand and optimize the electrode processes in electrochemical devices such as polymer electrolyte membrane fuel cells.

Merry-go-round: A benzoquinone (BQ) disk undergoes self-motion when coupled with an enzyme and redox reaction (see picture). The driving force is BQ, therefore the features of motion are determined by the reaction between BQ and HQ.

Pass the sugar: The protonation dynamics of adenine (Ade) and its nucleoside 2′-deoxyadenosine (d-Ade) are investigated by monitoring the deprotonation kinetics of acridine (Acr) in micelles. Quenching of the fluorescence of AcrH⁺* is observed after addition of Ade and d-Ade with a concomitant increment in Acr* (see picture). Excited-state proton-transfer (ESPT) takes place from AcrH⁺* to the bases, but is hindered by a 2′-deoxy sugar unit.

Seeing further: Metal-enhanced resonance energy transfer is presented for a model sensing film where silver nanoparticles can be formed in situ to increase the range of the energy-transfer process.

Anti-fibril: Ferrocene peptide conjugates bearing a podant (Lys)-Leu-Val-Phe-Phe motif strongly affect Amyloid beta peptide (Aβ_12–28) fibrillization, which is modulated by simple structural modifications of the C-terminal residues of the bioorganometallic probe. Interactions were followed electrochemically giving a “signal-on” response only for Fc-peptides that interact strongly with the Aβ films and affect Aβ aggregation in solution (see picture).

Semiconductor interfaces: The nanostructure-directed dynamics of acid/base interactions and the balance between physisorption and chemisorption on an extrinsic semiconductor interface is evaluated for n- and p-type semiconductors. Their responses to NO₂, NO, and NH₃ (see picture) correlate with the temperature dependence of the extrinsic semiconductor, the population of the donor or acceptor levels, and the inherent mobilities of electrons.

Ne quid nimis: Describing chemical reactions in solution by computational techniques developed for gas-phase scenarios might produce erroneous results (see histogram).

Water power: DFT calculations show that naphthalendiimides establish strong anion⋅⋅⋅π interactions in the gas phase (see picture). The presence of a small number of water molecules significantly alters the anion⋅⋅⋅π interaction, thereby suggesting its crucial role in overcoming dehydration costs.

Chiral films are obtained from achiral rigid–flexible molecules (see picture) on pure water subphase due to H-bonding and steric constraints of the rigid segments. On an aqueous AgNO₃-containing subphase the molecules can coordinate with Ag^I ions, forming macroscopic chiral films. This work gives important clues to the design and fabrication of chiral molecular assemblies from achiral molecules.

The decomposition of N₂O on stable composite catalysts of Sc-, Ti- and V-doped (5,5)SWCNTs (see picture) is investigated by periodic DFT calculations and is compared with the same process on pristine (5,5)SWCNTs.

Show me your fragments: Complexes of copper (II) ions and uracil were studied using tandem mass spectrometry including extensive isotopic labeling as well as theoretical calculations that allowed for a detailed fragmentation scheme for the [Cu(Ura-H)(Ura)]⁺ ion, beginning with the lowest energy structure.

Legacy: Electronegative/geometric perturbation of a biradical leads to a molecule with inherited biradicaloid character (see picture). This gives rise to a small HOMO–LUMO gap, a low-lying LUMO and small reorganization energies.