Photochemistry and Photobiology

Cover image for Vol. 90 Issue 2

March/April 2014

Volume 90, Issue 2

Pages 253–477

  1. Editorial

    1. Top of page
    2. Editorial
    3. Special issue dedicated to the memory of Nicholas J. Turro
    4. Invited Reviews
    5. Research Note
    6. Research Articles
    7. Erratum
    1. Editorial (page 253)

      Jean Cadet

      Article first published online: 14 MAR 2014 | DOI: 10.1111/php.12259

  2. Special issue dedicated to the memory of Nicholas J. Turro

    1. Top of page
    2. Editorial
    3. Special issue dedicated to the memory of Nicholas J. Turro
    4. Invited Reviews
    5. Research Note
    6. Research Articles
    7. Erratum
    1. Nicholas J. Turro, 1938–2012 (pages 254–256)

      Article first published online: 14 MAR 2014 | DOI: 10.1111/php.12221

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      This volume of Photochemistry and Photobiology contains a memoriam to Nicholas J. Turro (1938–2012). It is a collection of review articles and papers, dedicated to his memory, authored by those who remember him as a teacher, mentor, colleague and friend.

  3. Invited Reviews

    1. Top of page
    2. Editorial
    3. Special issue dedicated to the memory of Nicholas J. Turro
    4. Invited Reviews
    5. Research Note
    6. Research Articles
    7. Erratum
    1. You have free access to this content
      Singlet Oxygen Generation by Cyclometalated Complexes and Applications (pages 257–274)

      David Ashen-Garry and Matthias Selke

      Article first published online: 18 DEC 2013 | DOI: 10.1111/php.12211

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      Cyclometalated complexes are a relatively new class of singlet oxygen sensitizers. They generally have high singlet oxygen quantum yields, and their absorption spectra can be fine-tuned by judicious choice of ancillary ligands. One of the main advantages of these complexes is the relative ease with which they can be attached to biomolecules, polymers and nanostructures.

    2. You have free access to this content
      Coordination Chemistry-Assembled Multicomponent Systems Built from a Gable-Like Bis-Porphyrin: Synthesis and Photophysical Properties (pages 275–286)

      Maryline Beyler, Lucia Flamigni, Valérie Heitz, Jean-Pierre Sauvage and Barbara Ventura

      Article first published online: 30 OCT 2013 | DOI: 10.1111/php.12177

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      Various noncovalent multiporphyrinic assemblies could be built from a gable-like bis-Zn porphyrin. Both energy and electron transfer processes have been characterized in these assemblies. In the three-component system, unusual electron transfer from a Zn porphyrin to a free-base porphyrin was evidenced.

    3. You have free access to this content
      Visualizing Carbene Equilibria (pages 287–293)

      Robert A. Moss, Lei Wang, Pablo A. Hoijemberg and Karsten Krogh-Jespersen

      Article first published online: 30 JUL 2013 | DOI: 10.1111/php.12120

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      Laser flash photolysis UV–Vis spectrum of phenylchlorocarbene (PhCCl) in 0.75 mm trimethoxybenzene/pentane solution 50 ns after the laser flash. PhCCl absorptions are at 324 and 596 nm. The absorption of the PhCCl-trimethoxybenzene π complex is at 484 nm.

  4. Research Note

    1. Top of page
    2. Editorial
    3. Special issue dedicated to the memory of Nicholas J. Turro
    4. Invited Reviews
    5. Research Note
    6. Research Articles
    7. Erratum
    1. Fluorescence Excitation Spectrum of Bilirubin in Blood: A Model for the Action Spectrum for Phototherapy of Neonatal Jaundice (pages 294–296)

      Angelo A. Lamola and Marie Russo

      Article first published online: 10 DEC 2013 | DOI: 10.1111/php.12167

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      Not Too Blue and Not Too Green: Current knowledge of the optical properties of skin provides a model that predicts the action spectrum for phototherapy of neonatal jaundice to be relatively narrow and peaked near 475 nm. A physical analog, the fluorescence excitation spectrum of bilirubin in blood, is in agreement with the calculated action spectrum.

  5. Research Articles

    1. Top of page
    2. Editorial
    3. Special issue dedicated to the memory of Nicholas J. Turro
    4. Invited Reviews
    5. Research Note
    6. Research Articles
    7. Erratum
    1. Why is Rose Bengal More Phototoxic to Fibroblasts In Vitro Than In Vivo? (pages 297–305)

      Min Yao, Chuan Gu, Francis J. Doyle Jr., Hong Zhu, Robert W. Redmond and Irene E. Kochevar

      Article first published online: 16 DEC 2013 | DOI: 10.1111/php.12215

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      Rose Bengal (RB) is well known to cause phototoxicity by a singlet-oxygen mechanism to cultured cells. However, when we used RB photosensitization to seal wounds or stiffen tissue by cross-linking tissue collagen, the tissue cells were not killed. Using fibroblasts in collagen gels as a tissue model, we demonstrated that the cells are protected by upregulation of prosurvival pathways, depletion of oxygen and irradiance-dependent RB photochemistry.

    2. Chemosensitization of Cancer Cells via Gold Nanoparticle-Induced Cell Cycle Regulation (pages 306–312)

      Megan A. Mackey and Mostafa A. El-Sayed

      Article first published online: 11 FEB 2014 | DOI: 10.1111/php.12226

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      Gold nanoparticles that target the nucleus of cancer cells have the ability to regulate the cell cycle, causing cells to accumulate in the S phase. A common chemotherapeutic agent, 5-Fluorouracil, is most effective at inducing cell death when cells are in the S phase of the cell cycle. Therefore, treatment with 5-Fluorouracil is preceded by treatment with nuclear-targeting gold nanoparticles to allow for an enhanced S phase population, resulting in enhanced drug efficacy (i.e. chemosensitization).

    3. N-Alkoxyheterocycles As Irreversible Photooxidants (pages 313–328)

      Zofia M. Wosinska, Faye L. Stump, Rajeev Ranjan, Edward D. Lorance, GeNita N. Finley, Priya P. Patel, Muzamil A. Khawaja, Katie L. Odom, Wolfgang H. Kramer and Ian R. Gould

      Article first published online: 16 JAN 2014 | DOI: 10.1111/php.12227

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      The return or reverse electron transfer that occurs in the primary charge-separated pair that is a feature of all photoinduced electron transfer reactions wastes energy and competes with useful chemistry in the charge-separated species. Here, we describe photoinduced electron transfer schemes that made irreversible by using fragmentable sensitizers. The fragmentable sensitizers are N-methoxyheterocycles that cleave a relatively weak N–O bond in either their reduced or excited forms. Sensitization mechanisms in both the singlet and the triplet manifolds are described. Irreversible oxidation of guanosine is demonstrated as an illustrative example.

    4. A2E-Mediated Photochemical Modification to Fibronectin and its Implications to Age-Related Changes in Bruch's Membrane (pages 329–334)

      Mai T. Thao, Daniel J. Renfus, James Dillon and Elizabeth R. Gaillard

      Article first published online: 28 NOV 2013 | DOI: 10.1111/php.12200

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      The bis-retinoid A2E is the major fluorophore in lipofuscin. Blue-light–irradiated A2E generates a variety of reactive aldehydes that alter the structure of fibronectin. The additions of A2E derived aldehydes resemble the Maillard reaction. These results can be used to identify similar modifications that occur in Bruch's membrane in vivo.

    5. Transient Spectroscopy of 5,7-diiodo-3-butoxy-6-fluorone (DIBF) (pages 335–337)

      Igor L. Zheldakov, Oleg Grinevich, Alexander Mejiritski, Christopher G. Elles and Douglas C. Neckers

      Article first published online: 25 NOV 2013 | DOI: 10.1111/php.12190

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      Transient absorption spectroscopy examines the role of DIBF as a visible light photosensitizer in cationic polymerization. Rapid intersystem crossing produces a reactive triplet state of DIBF, which subsequently activates an ultraviolet absorbing photoinitiator (OPPI). Addition of 9,10-diethoxyanthracene (AN 910 E) dramatically accelerates polymerization by facilitating the activation of OPPI from the triplet state of DIBF, although electron or energy transfer is too slow to observe within the 1 ns window of the experiment.

    6. Aliphatic β-Nitroalcohols for Therapeutic Corneoscleral Cross-Linking: Chemical Stability Studies Using 1H-NMR Spectroscopy (pages 338–343)

      Xia Li, Yongjun Li, MiJung Kim, Stephen L. Trokel, Nicholas J. Turro and David C. Paik

      Article first published online: 21 OCT 2013 | DOI: 10.1111/php.12165

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      Certain β-nitroalcohols undergo a base-catalyzed thermally driven retronitroalcohol reaction to give formaldehyde under physiologic conditions. Because they also exhibit a favorable safety profile (unlike free formaldehyde), they represent a potentially useful class of agents for clinical therapeutic corneoscleral tissue cross-linking. In this brief report, compound stability under long-term storage conditions was studied in anticipation of clinical translation of this potential treatment modality. Higher order nitroalcohols (a nitrodiol and nitrotriol) were found to be significantly more stable than their mononitroalcohol counterparts.

    7. Synthesis, Characterization, Photophysics and Photochemistry of Pyrylogen Electron Transfer Sensitizers (pages 344–357)

      Edward L. Clennan and Chen Liao

      Article first published online: 30 OCT 2013 | DOI: 10.1111/php.12174

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      Hybrids of pyrylium salts and viologens photochemically generate radical-cation/radical-cation pairs with substantial intra-ion repulsion that increases the rate constant of separation, kSEP, and competitively inhibits energy wasting return electron transfer. These first representatives of dicationic charge-shift sensitizers generate radical cations that do not react with oxygen on the CV timescale and absorb between 413 and 523 nm well outside the range where competitive absorbance by most substrates would cause a problem.

    8. Immobilized Organic Photosensitizers with Versatile Reactivity for Various Visible-Light Applications (pages 358–368)

      Filippo Ronzani, Philippe Saint-Cricq, Emmanuel Arzoumanian, Thierry Pigot, Sylvie Blanc, Michael Oelgemöller, Esther Oliveros, Claire Richard and Sylvie Lacombe

      Article first published online: 25 OCT 2013 | DOI: 10.1111/php.12166

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      The properties and applications of several silica materials, containing anthraquinone and cyanoanthracene derivatives as photosensitizers, have been investigated. Besides the photochemistry results, either for liquid α-terpinene or gaseous dimethylsulfide oxidation, the direct detection of the transient species and the determination of singlet oxygen lifetimes and quantum yields in highly transparent and porous silica monoliths were carried out. This overview allows a critical comparison of the properties of the sensitizers, and of various silica macrostructurations. The visible-light activity of these easily prepared materials opens the route to tunable green photochemistry.

    9. Decay Kinetics of Benzophenone Triplets and Corresponding Free Radicals in Soft and Rigid Polymers Studied by Laser Flash Photolysis (pages 369–373)

      Peter P. Levin, Alexei F. Efremkin, Natalie B. Sultimova, Valery V. Kasparov and Igor V. Khudyakov

      Article first published online: 19 OCT 2013 | DOI: 10.1111/php.12170

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      The kinetics of transients formed under photoexcitation of benzophenone (B) dissolved in two soft rubbery polymers and hard polystyrene was studied by ns laser flash photolysis. We observed exponential decay of 3B* and two-stage decay kinetics of BHin poly(ethylene-co-butylene) (EB). The first stage is a fast cage recombination of a radical pair (BH, radical of polymer R). Application of a magnetic field (MF) of 0.2 T leads to deceleration of both stages of BH decay in EB by approximately 20%. We discuss the effects of polymer structure on transients kinetics and the MF effect.

    10. Effects of Light Energy and Reducing Agents on C60-Mediated Photosensitizing Reactions (pages 374–379)

      Michael Quinones, Yazhou Zhang, Penelope Riascos, Huey-Min Hwang, Winfred G. Aker, Xiaojia He and Ruomei Gao

      Article first published online: 2 DEC 2013 | DOI: 10.1111/php.12206

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      The photosensitization pathways of C60 vary with the irradiation energy and reducing agents. C60/visible light-initiated Type-I reactions take place only in the presence of electron donors with the formation yield of superoxide anions below 0.2 in dipolar aprotic solvents. Under UVA irradiation, both C60 and UVA-active reducing agents may produce reactive oxygen species, leading to a synergistic toxicity.

    11. Brush-first and Click: Efficient Synthesis of Nanoparticles that Degrade and Release Doxorubicin in Response to Light (pages 380–385)

      Alan O. Burts, Longyan Liao, Ying Y. Lu, David A. Tirrell and Jeremiah A. Johnson

      Article first published online: 25 NOV 2013 | DOI: 10.1111/php.12182

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      Brush-first ring-opening metathesis copolymerization of a poly(ethylene glycol) (PEG)-branch-alkyl chloride macromonomer with a photocleavable bis norbornene crosslinker leads to the formation of brush-arm star polymer (BASP) nanostructures with PEG coronas, photocleavable cores and alkyl chloride functionalities. Conversion of these chlorides to azides, followed by copper-catalyzed azide–alkyne ‘click’ conjugation of a caged doxorubicin (DOX)-alkyne derivative, yielded BASPs that simultaneously degrade and release DOX upon exposure to 365 nm light. These materials displayed low toxicity against MCF-7 human cancer cells in the absence of light; irradiation led to IC50 values similar to that of free DOX.

    12. Oxidation of Plasmalogen, Low-Density Lipoprotein and RAW 264.7 Cells by Photoactivatable Atomic Oxygen Precursors (pages 386–393)

      Max T. Bourdillon, Benjamin A. Ford, Ashley T. Knulty, Colleen N. Gray, Miao Zhang, David A. Ford and Ryan D. McCulla

      Article first published online: 28 NOV 2013 | DOI: 10.1111/php.12201

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      The photodeoxygenation of dibenzothiophene S-oxide has been suggested to generate ground state atomic oxygen (O[3P]). The reactivity of the putative O(3P) is distinct from other reactive oxygen species (ROS) and little is known about its reactivity with lipids and other biomolecules. In this work, exposure of low-density lipoprotein (LDL) to O(3P) yielded four aldehyde products. The same aldehydes were observed after the oxidation of an isolated plasmalogen by O(3P).

    13. 1H NMR Study of Hydrogen Abstraction in Model Compound Mimics of Polymers (pages 394–401)

      Jeffrey R. Lancaster, Rachael Smilowitz, Nicholas J. Turro and Jeffrey T. Koberstein

      Article first published online: 13 DEC 2013 | DOI: 10.1111/php.12214

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      Small molecules representing common synthetic polymers were subjected to photochemically induced hydrogen abstraction by benzophenone. Reactions were monitored using 1H NMR to query the factors that influence preferential abstraction of protons in unique chemical environments. Differences in bond dissociation energies do not fully explain the observed hydrogen abstraction preferences. Using representative small molecule model compounds in lieu of polymeric materials is a novel approach to understanding photochemical reaction in polymers; however, it cannot probe the contributions of macromolecular effects—e.g. polymer rigidity or side chain and backbone mobility—to preferential hydrogen abstraction.

    14. A Spectroscopic and Theoretical Investigation of a Free-Base meso-Trithienylcorrole (pages 402–414)

      Jordan A. Greco, Alison Rossi, Robert R. Birge and Christian Brückner

      Article first published online: 5 DEC 2013 | DOI: 10.1111/php.12203

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      The unique optical properties of free-base meso-trithienylcorrole in its neutral, mono-anionic and mono-cationic forms were compared to those of the widely investigated meso-triphenyl-substituted analogue using a combination of spectroscopic and computational experiments. The generally bathochromically shifted spectra measured for the thienyl-substituted corrole were found to be due to a more nonplanar macrocycle conformation in conjunction with a high degree of π-overlap with the meso-substituents.

    15. Computational Study of the Surface-Enhanced Raman Scattering from Silica-Coated Silver Nanowires (pages 415–418)

      Brent M. DeVetter, Rohit Bhargava and Catherine J. Murphy

      Article first published online: 8 DEC 2013 | DOI: 10.1111/php.12205

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      The surface-enhanced Raman scattering (SERS) characteristics of patchy silica-coated silver nanowires were investigated using the finite element method. Two processes govern the predicted electromagnetic enhancement. The first process is related to changes in the dielectric environment surrounding the nanowire due to the patchy silica coating. Silica layers cause the localized surface plasmon resonance of the nanowire to redshift, subsequently altering its optical properties. The second process is related to the distortion of the plasmonic fields caused by the silica. We propose that control over the placement and structure of patchy silica can be used to rationally design nanowire-based sensors.

    16. Photophysics of Glycosylated Derivatives of a Chlorin, Isobacteriochlorin and Bacteriochlorin for Photodynamic Theragnostics: Discovery of a Two-photon-absorbing Photosensitizer (pages 419–430)

      Amit Aggarwal, Sebastian Thompson, Sunaina Singh, Brandon Newton, Akeem Moore, Ruomie Gao, Xinbin Gu, Sushmita Mukherjee and Charles Michael Drain

      Article first published online: 28 NOV 2013 | DOI: 10.1111/php.12179

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      Click-type chemistry allows tetraglycosylation of the perfluorophenyl derivatives of a chlorin, bacteriochlorin, and an isobacteriochlorin in high yields. The four non-hydrolysable sugars target the chromophores to mouse models of head and neck squamous cell carcinoma. Here the glycosylated chlorin allows fluorescence imaging of these tumors.

    17. Theoretical Study of the Reaction Formalhydrazone with Singlet Oxygen. Fragmentation of the C=N Bond, Ene Reaction and Other Processes (pages 431–438)

      Benjamin Rudshteyn, Álvaro Castillo, Ashwini A. Ghogare, Joel F. Liebman and Alexander Greer

      Article first published online: 2 DEC 2013 | DOI: 10.1111/php.12199

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      Coupled cluster and density functional theory calculations were carried out for the formalhydrazone and 1O2 reaction to investigate C=N bond cleavage and N-nitrosamine formation. A 3-amino-1,2,3-dioxazetidine intermediate is found to arise from a [2 + 2] reaction that should rapidly collapse to N-nitrosamine and formaldehyde, but a lower activation energy is calculated for an ‘ene’ process to a hydroperoxymethyl diazene species. A minimum energy structure for the 2-amino-oxaziridine-O-oxide (perepoxide-like) intermediate was not located.

    18. Interaction of H2@C60 and Nitroxide through Conformationally Constrained Peptide Bridges (pages 439–447)

      Luca Garbuio, Yongjun Li, Sabrina Antonello, José A. Gascón, Ronald G. Lawler, Xuegong Lei, Yasujiro Murata, Nicholas J. Turro and Flavio Maran

      Article first published online: 28 NOV 2013 | DOI: 10.1111/php.12191

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      We synthesized two molecular systems, in which a nitroxide and an endofullerene C60, incarcerating one hydrogen molecule (H2@C60), are connected by a folded 310-helical peptide. Despite the similar apparent distance r, reversing the orientation of the peptide bridge significantly affects the nuclear spin relaxation rate and the para → ortho conversion rate of the incarcerated hydrogen molecule. Overall, the results strengthen the outcome of previous investigations that while the conversion rates satisfactorily obey the Wigner's theory, the relaxation rates are in excellent agreement with the Solomon–Bloembergen equation.

    19. The Contribution of Reactive Oxygen Species to the Photobleaching of Organic Fluorophores (pages 448–454)

      Qinsi Zheng, Steffen Jockusch, Zhou Zhou and Scott C. Blanchard

      Article first published online: 2 DEC 2013 | DOI: 10.1111/php.12204

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      Photoexcitation of fluorophores generates reactive oxygen species (ROS) which can cause bleaching of the fluorophore and damage to the biological system. We show that singlet oxygen contributes relatively little to Cy5 and ATTO 647N photobleaching at low concentrations in aqueous solution. We also show that Cy5 generates significantly less ROS when covalently linked to the protective agents, cyclooctatetraene (COT), nitrobenzyl alcohol (NBA) or Trolox. Such fluorophores exhibit enhanced photostability and generated less ROS than fluorophores that are commonly used, suggesting that they may be substantially less phototoxic than the common fluorophores.

    20. Enzyme Activity and Structural Dynamics Linked to Micelle Formation: A Fluorescence Anisotropy and ESR Study (pages 455–462)

      Michael Chin and Ponisseril Somasundaran

      Article first published online: 5 DEC 2013 | DOI: 10.1111/php.12207

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      The activities of subtilisin protease and horse radish peroxidase (HRP) in the presence of the sugar-based surfactant alkyl polyglucoside have been increased relative to that of enzyme in buffer solution alone. The mechanism of this enhancement appears to be related to micelle aggregate structure. Surface tension, dynamic light scattering and electron spin resonance were used to elucidate the specific micelle conformations that induce the observed hyperactivity. Time-resolved fluorescence spectroscopy has also been used to investigate changes in the active site flexibility and has demonstrated greater structural mobility with surfactant concentration.

    21. One-Component Thioxanthone Acetic Acid Derivative Photoinitiator for Free Radical Polymerization (pages 463–469)

      Duygu S. Esen, Gokhan Temel, Demet K. Balta, Xavier Allonas and Nergis Arsu

      Article first published online: 24 DEC 2013 | DOI: 10.1111/php.12218

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      Acetic acid based thioxanthone (TXCH2COOH) phototinitiator has two absorption bands 379 and 574 nm respectively and unusual absorption of TXCH2COOH makes very valuable as a photoinitiator. Fluorescence quantum yield was found as 0.09 and triplet lifetime was calculated as 2.3 μs. Initiation mechanism of TXCH2COOH based on intermolecular hydrogen abstraction followed by decarboxylation reaction, leads to production of initiating radicals for polymerization of acrylates and methacrylates.

    22. Photochemical Generation of 9H-Fluorenyl Radicals (pages 470–475)

      Tatiana Dyblenko, Andrei Chtchemelinine, Ryan Reiter, Ruhul Q. Chowdhury, Alexander Enaya, Hanan Afifi, Rene Fournier, Gabriela Mladenova, Alfred Barry P. Lever and Edward Lee-Ruff

      Article first published online: 10 JAN 2014 | DOI: 10.1111/php.12225

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      Substituted 9-fluorenols and 9,9′-bifluorenyls undergo photolysis to give products derived from 9-fluorenyl radicals. These intermediates decay by hydrogen abstraction giving 9H-fluorenes, or coupling to 9,9′bifluorenyls. The 9-trifluoromethyl-9-fluorenyl radical undergoes an unusual coupling to the unsymmetrical 9,3′-bifluorenyl.

  6. Erratum

    1. Top of page
    2. Editorial
    3. Special issue dedicated to the memory of Nicholas J. Turro
    4. Invited Reviews
    5. Research Note
    6. Research Articles
    7. Erratum
    1. You have free access to this content
      A Comparative Pilot Study of Symptom Improvement Before and After Phototherapy in Korean Patients with Perennial Allergic Rhinitis (pages 751–757) (page 476)

      Heung-Man Lee, Man Sik Park, Il Ho Park, Seung Hoon Lee, Seong Keon Lee, Kyu-Sung Kim and Hyuk Choi

      Article first published online: 14 MAR 2014 | DOI: 10.1111/php.12260

      This article corrects:
    2. You have free access to this content

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