The donor–acceptor dyad based on high substituted fullero[70]pyrrolidine-coordinated manganese (III) phthalocyanine for photoinduced electron transfer

Abstract

Donor-acceptor dyads based on manganese porphyrins/phthalocyanines and fullerene derivatives with N-basicity centers have proved as promising photoinduced electron-transfer systems for photovoltaic devices, biologically active compounds, and molecular magnetic materials. The macroheterocyclic chromophore characterized by rich UV–visible-near IR absorption is the basis for the applications above. The problem of the synthesis and the characterization of new effective dyads was solved in this work on the example of the self-organizing system consisting of (octakis-3,5-di-tert-butylphenoxy)phthalocyaninato)manganese(III) acetate, (AcO)MnPc(3,5-di-tBuPhO)8, 2′,5-di(pyridin-2′-yl)-3,4-fullero[70]pyrrolidine, Py2C70, and toluene. The phthalocyanine-fullerene dyads in the molecular and cationic form (respectively (AcO)(Py2C70)MnPc(3,5-di-tBuPhO)8 and [(Py2C70)MnPc(3,5-di-tBuPhO)8]+(AcO)-) were observed and described using the chemical kinetics/thermodynamics, UV–vis, IR, 1H NMR spectroscopy and mass spectrometry methods. The 1: 1 stoichiometry of both dyads was confirmed; the equilibrium and rate constant value, K= (4.86 ± 0.56) × 104 L mol−1 and k = (4.455 ± 3.37) × 10-5 s−1 was observed for the formation of molecular and cationic dyad, respectively. The study of (AcO)MnPc(3,5-di-tBuPhO)8 and [(Py2C70)MnPc(3,5-di-tBuPhO)8]+AcO- femtosecond transient absorption spectra points to the photoinduced electron transfer in the dyad, for which the lifetimes and the rate constants of charge separation (τCS, kCS) and charge recombination (τCR, kCR) were defined. The analysis of the relationship of the dyad physicochemical parameters with the molecular structure is represented using previously published data.