Self-assembling cobalt(II) porphyrin - fullero [60]pyrrolidine triads. Synthesis and spectral properties in the ground and excited state

Abstract

Meso‑4-Trifluoromethylphenyl substituted cobalt(II)porphin, CoT(CF3P)P, and its coordination 1: 2 complex (triad) with 1-N-methyl-2-(pyridin-4-yl)-3,4-fullero [60]pyrrolidine, (PyC60)2CoT(CF3P)P, were firstly synthesized and the properties of their molecular solutions were studied. The chemical structure of CoT(CF3P)P and triad was fully confirmed by the UV–vis, IR and 1H NMR spectroscopy and mass spectrometry methods. The triad formation mechanism as the two-step equilibrium characterized by equilibrium constant K1 (5.89 ± 1.50) × 104 M−1 and K2 (7.40 ± 1.66) × 105 M−1 was revealed. Using femtosecond pump-probe spectroscopy measurements, the photoinduced electron transfer in the synthesized triad was described. The excited state lifetime of the precursors, CoTPP, CoT(CF3P)P and the charge separated state lifetime of (PyC60)2CoT(CF3P)P compared with unsubstituted (PyC60)2CoTPP were determined. It was established that the CF3 groups in the porphyrin periphery slightly change the CoTPP/CoT(CF3P)P excited state lifetime and the electron transfer rate constant in the correspondent triads.