Photochemical study of the zinc cis-3-(4-imidazolylphenyl)-1-(pyridin-2-yl)[60]fullereno[1,2-c]pyrrolidine-meso-tetraphenylporphyrinate dyad

Abstract

Axial coordination of fullerenopyrrolidine bearing the donor imidazolyl group, cis-3-(4-imidazolylphenyl)-1-(pyridin-2-yl)[60]fullereno[1,2-c]pyrrolidine (C60∼Im), with zinc meso-tetraphenylporphyrinate (ZnTPP) in an o-dichlorobenzene solution affords a non-covalently bonded donor-acceptor dyad ZnTPP-C60∼Im. The photochemical behavior of the ZnTPP-C60∼Im complex was studied by fluorescence (excitation at λ = 420 nm) and laser kinetic spectroscopy (excitation at λ = 532 nm, 12 ns). The formation constant of the 1: 1 porphyrin-fullerenopyrrolidine complex determined from quenching of ZnTPP fluorescence assuming static intracomplex quenching is 1.6·104 L mol−1. Absorption spectra of the excited states in the system consisting of ZnTPP and Im∼C60 (ZnTPP/C60∼Im) were measured in solution from 380 to 1000 nm. The quenching constant of the triplet-excited ZnTPP with fullerenopyrrolidine C60∼Im was determined. The results obtained indicate the formation of the triplet exciplex {PL}* ⇌ {Pδ+…Lδ−} in the ZnTPP/C60∼Im system upon laser photolysis.