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New Biological Pigments Findings from Yonsei University Described (Photoinduced Electron Transfer from a Tetrathiafulvalene-Calix[4]pyrrole to a...

August 5, 2014



New Biological Pigments Findings from Yonsei University Described (Photoinduced Electron Transfer from a Tetrathiafulvalene-Calix[4]pyrrole to a Porphyrin Carboxylate within a Supramolecular Ensemble)

By a News Reporter-Staff News Editor at Life Science Weekly -- Current study results on Biological Factors have been published. According to news reporting from Seoul, South Korea, by NewsRx journalists, research stated, "A supramolecular assembly is formed upon mixing millimolar concentrations of a tetrakis-tetrathiafulvalene calix[4]pyrrole (TTF-C4P) and a porphyrin tetraethylammonium carboxylate salt in benzonitrile (PhCN). The TTF-C4P binds to the carboxylate moiety of the porphyrin with a 1:1 stoichiometry and a binding constant of 6.3 x 10(4) M-1 in this solvent at 298 K. Laser photoexcitation of the supramolecular complex results in formation of the triplet charge-separated (CS) state composed of a radical cation of the TTF-C4P receptor and the radical anion of the porphyrin carboxylate."

The news correspondents obtained a quote from the research from Yonsei University, "These processes and the resulting states were characterized by means of transient absorption and electron spin resonance (ESR) spectroscopies. The rate constants corresponding to the forward and backward intramolecular electron-transfer (ET) processes were determined to be 2.1 x 10(4) and 3.6 x 10(2) s(-1), respectively. The rate constants of intermolecular forward and backward electron transfer were also determined to be 4.4 x 10(8) and 9.8 x 10(8) M-1 s(-1), respectively. The electronic coupling constant (V), 1.2 x 10(-2) cm(-1), and the reorganization energy (lambda), 0.76 eV, for back electron transfer were evaluated from the temperature dependence of the rate constants of intramolecular electron transfer. The small V value indicates little spin-forbidden interaction between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) and substantiates the long-lived CS lifetime."

According to the news reporters, the research concluded: "These results were corroborated by density function theory (DFT) calculations, which provided support for the conclusion that the HOMO and LUMO, located on a TTF moiety of the TTF-C4P and the porphyrin core, respectively, have little interaction though space."

For more information on this research see: Photoinduced Electron Transfer from a Tetrathiafulvalene-Calix[4]pyrrole to a Porphyrin Carboxylate within a Supramolecular Ensemble. Journal of Physical Chemistry C, 2014;118(25):13503-13513. Journal of Physical Chemistry C can be contacted at: Amer Chemical Soc, 1155 16TH St, NW, Washington, DC 20036, USA. (American Chemical Society - www.acs.org; Journal of Physical Chemistry C - www.pubs.acs.org/journal/jpccck)

Our news journalists report that additional information may be obtained by contacting C.M. Davis, Yonsei University, Dept. of Chem, Seoul 120749, South Korea. Additional authors for this research include Y. Kawashima, K. Ohkubo, J.M. Lim, D. Kim, S. Fukuzumi and J.L. Sessler (see also Biological Factors).

Keywords for this news article include: Asia, Seoul, Porphyrins, South Korea, Nanotechnology, Supramolecular, Biological Factors, Biological Pigments, Emerging Technologies

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


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Source: Life Science Weekly


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