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Formation of a hybrid compound composed of a saddle-distorted Tin(IV)-porphyrin and a keggin-type heteropolyoxometalate to undergo intramolecular photoinduced electron transfer

Title
Formation of a hybrid compound composed of a saddle-distorted Tin(IV)-porphyrin and a keggin-type heteropolyoxometalate to undergo intramolecular photoinduced electron transfer
Authors
Yokoyama A.Kojima T.Ohkubo K.Shiro M.Fukuzumi S.
Ewha Authors
Shunichi Fukuzumi
SCOPUS Author ID
Shunichi Fukuzumiscopus
Issue Date
2011
Journal Title
Journal of Physical Chemistry A
ISSN
1089-5639JCR Link
Citation
vol. 115, no. 6, pp. 986 - 997
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
Nonplanar Sn(IV)-porphyrin complexes, [Sn(TMPP(Ph) 8)-Cl 2] (1) and [Sn(TMPP(Ph) 8)(OMe) 2] (2) (TMPP(Ph) 8: 5,10,15,20-tetrakis(4-methoxyphenyl)-2,3,7,8,12,13,17,18- octaphenylporphyrinato), were prepared and characterized by spectroscopic and electrochemical methods together with X-ray crystallography. Variable-temperature 1H NMR study revealed that the coordination of the methoxo ligand of 2 is weak enough in solution to enhance the axial ligand exchange with a Keggin-type phosphotungstate (α-[PW 12O 40] 3-) due to the steric stress between the axial methoxo ligand and the peripheral phenyl groups of the porphyrin ligand. The formation of a novel 1:1 donor-acceptor complex, [Sn(TMPP(Ph) 8)(OMe)(α- [PW 12O 40])] 2- (4) was confirmed by 1H NMR and UV-vis spectral titrations, and also by MALDI-TOF-MS measurements. Electrochemical measurements for the donor-acceptor complex in PhCN revealed that the Sn(IV)-TMPP(Ph) 8 moiety acts as an electron donor and the α-[PW 12O 40] 3- moiety acts as an electron acceptor and that the energy level of the electron-transfer (ET) state of the 1:1 complex (1.17 eV) is lower than that of the triplet excited states of the SnTMPP(Ph) 8 complex (1.31 eV). Femtosecond and nanosecond laser flash photolysis measurements indicate that intersystem crossing from the singlet excited sate to the triplet excited state occurs followed by intramolecular photoinduced electron transfer from the triplet excited state of the Sn(IV)-TMPP(Ph) 8 moiety to the α-[PW 12O 40] 3- moiety in the 1:1 complex in benzonitrile. © 2011 American Chemical Society.
DOI
10.1021/jp109863d
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자연과학대학 > 화학·나노과학전공 > Journal papers
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