Exploring the chemical physics in tetraphenylporphyrin-N-methylfulleropyrrolidine supramolecular complex by spectroscopic investigations and quantum chemical calculations

Abstract

The interaction between N-methylfulleropyrrolidine (A) and 5,10,15,20-tetraphenylporphyrin, i.e., D, is studied in solution. Absorption spectrophotometric study reveals formation of charge transfer (CT) absorption band for the DA complex from which CT transition energy (hνCT) is estimated to be 1.673 eV. Quenching of fluorescence of D in presence of A is utilized for determination of the binding constant of the DA complex as 13780 dm3⋅mol−1. DFT calculations generate both geometry optimized and electronic structures of the DA complex and the estimated HOMO-LUMO energy gap, i.e., 1.683 eV, correlates excellently well with the experimentally obtained value of hνCT. Proton NMR studies provide substantial support in favour of strong binding between D and A and provide a clear picture regarding orientation of bound guest (here A) with host (here D). The DA system reported in present work would certainly provide very good perspective for the construction of fulleropyrrolidine based photochromic devices in near future.