Carbazole-functionalized cobalt(ii) porphyrin axially bonded with C₆₀/C₇₀ derivatives: synthesis and characterization

Two supramolecular cobalt(II) porphyrin–fullerene systems, (PyC60)2CoDTBCP/(Py2C70)CoDTBCP, self-assembled via axial coordination of 1-N-methyl-2-(pyridin-4-yl)-3,4-fullero[60]pyrrolidine and 2,5-di-(pyridin-2-yl)-3,4-fullero[70]pyrrolidine by (5,15-bis[3,5-bis(tert-butyl)phenyl]-10,20-bis[4,6-(4-(3,6-di-tert-butyl-9H-carbazol-9-yl)phenyl)pyrimidin-5-yl]porphinato)cobalt(II), respectively, were prepared and characterized for the first time. Target carbazole-functionalized cobalt(II) porphyrin was synthesized by direct metallation of the corresponding porphyrin that was in its turn obtained by tetra-substitution of 5,15-bis[4,6-dichloropyrimidin-5-yl]porphyrin with 4-(3,6-di-tert-butyl-9H-carbazol-9-yl)phenol. All compounds synthesized were fully characterized by mass spectrometry and UV-vis, IR, and 1H NMR spectroscopy. Chemical structure and spectral properties of the triad/dyad were additionally described using chemical thermodynamics, kinetics, and DFT calculations. The analysis of the geometric and electronic structures of the (PyC60)2CoDTBCP and (Py2C70)CoDTBCP FMOs in the ground state and the study of their femtosecond transient absorption spectra points to the existence of photoinduced electron transfer in the triad and dyad. The data obtained are required for further photoelectrochemical study of the triad/dyad and determining their potential in the building of photovoltaic devices.