Synthesis and Photophysical Properties of Porphyrin–Arylimidazole Heterodyads

Abstract

A series of directly linked metalloporphyrin–arylimidazole heterodyads (3, 4, and 6) with an arylimidazole unit at the meso‐ or β‐pyrrolic position of the porphyrin were synthesized via Debus–Radziszewsk reaction. Introduction of a copper ion into the porphyrin contributed significantly to the overall stability of the heterodyads. The absorption spectra indicated that the basic electronic characteristics of both individual units (i.e., metalloporphyrin and arylimidazole) were retained in the heterodyads. In addition, strong fluorescence quenching was observed in the case of the heterodyads containing copper(II) porphyrin. Cyclic voltammetric studies revealed that the heterodyads were more difficult to oxidize compared with the pristine metalloporphyrins.

Efficient Approach to Functionalized β-Imidazolylporphyrins

“…[16] Single example of the application of Debus-Radziszewsky condensation with 2-formylporphyrin is already reported for the formation of 4,5-diphenylimidazol-2-yl fragment. [17] Nevertheless, the mentioned example remains occasional and the potential of employment of -diketones in the synthesis of -imidazolylporphyrins is currently unstudied. Moreover, the synthetic availability and chemical stability of aromatic dioxoderivatives in comparison with the corresponding diamines makes them attractive starting compounds for the preparation of a variety of functional porphyrins.…”