π-complex formation in electron-transfer reactions of porphyrins

Shunichi Fukuzumi, Taku Hasobe, Kei Ohkubo, Maxwell J. Crossley, Prashant V. Kamat, Hiroshi Imahori

Research output: Contribution to journalShort surveypeer-review

13 Citations (Scopus)

Abstract

π-Complex formation between porphyrins and their radical cations plays an important role in self-exchange electron transfer between neutral porphyrins and the radical cations, leading to negative activation enthalpies when the stabilization energy of the π-complex is larger than the activation energy for the intracomplex electron transfer in the π-complex. A number of porphyrin molecules are self-organized on three-dimensional gold nanoclusters to form monolayer-protected gold nanoclusters (MPCs) that act as an efficient photocatalyst for the uphill reduction of HV2+ by BNAH to produce l-benzylnicotinamidinium ion (BNA+) and hexyl viologen radical cation (HV.+). Such three-dimensional architectures of porphyrin MPCs with large surface area allow supramolecular π-complexation between MPCs and HV+2, resulting in fast electron transfer from the singlet excited state of porphyrin to HV2+ on MPCs. The π-π interaction is exploited to develop efficient photovoltaic devices consisting of porphyrin and fullerene assemblies which have an enhanced light-harvesting efficiency throughout the solar spectrum together with a highly efficient conversion of the harvested light into electrical energy.

Original languageEnglish
Pages (from-to)191-200
Number of pages10
JournalJournal of Porphyrins and Phthalocyanines
Volume8
Issue number1-3
DOIs
Publication statusPublished - 2004
Externally publishedYes

Keywords

  • Electron transfer
  • Fullerene
  • Photovoltaic cell
  • Porphyrin dendrimer
  • π-complex

ASJC Scopus subject areas

  • Chemistry(all)

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