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

Axial coordination of fullerenopyrrolidine bearing the donor imidazolyl group, cis-3-(4-imidazolylphenyl)-1-(pyridin-2-yl)[60]fullereno[1,2-c]pyrrolidine (C-60 similar to Im), with zinc meso-tetraphenylporphyrinate (ZnTPP) in an o-dichlorobenzene solution affords a non-covalently bonded donor-acceptor dyad ZnTPP-C-60 similar to Im. The photochemical behavior of the ZnTPP-C-60 similar to Im complex was studied by fluorescence (excitation at lambda = 420 nm) and laser kinetic spectroscopy (excitation at lambda = 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(.)10(4) L mol(-1). Absorption spectra of the excited states in the system consisting of ZnTPP and Im similar to C-60 (ZnTPP/C-60 similar to Im) were measured in solution from 380 to 1000 nm. The quenching constant of the triplet-excited ZnTPP with fullerenopyrrolidine C-60 similar to Im was determined. The results obtained indicate the formation of the triplet exciplex {PL}* reversible arrow {P delta+ ... L-delta} in the ZnTPP/C-60 similar to Im system upon laser photolysis.