Synthesis, characterization and spectroscopic properties of novel periphery – functionalized unsymmetrical porphyrazines containing mixed dithienylpyrrolyl and dimethylamino groups

Following our previous report on a novel class of C4 symmetric porphyrazines bearing 2,5-dimethylpyrrolyl and methyl(3-pyridylmethyl)amino groups in the periphery, here we report the synthesis and characterization of unsymmetrical porphyrazines with peripheral 2,5-di(2-thienyl)pyrrolyl and dimethylamino groups that break the molecular C4 symmetry. The porphyrazines were prepared via macrocyclization reactions of a dinitrile precursor. Variable-temperature 1H NMR experiments, single crystal X-ray work and UV–Vis spectra in different solvents of the unsymmetrical magnesium porphyrazine provided information on the structural and electronic features of the entire macrocyclic system. A detailed discussion of the UV–Vis spectra in different solvents emphasizes the role played by the extended peripheral 2,5-di(2-thienyl)pyrrolyl substituent.

Graphical abstractThe novel porphyrazines bearing mixed dithienylpyrrolyl and dimethylamino groups in the periphery have been prepared via macrocyclization reaction. The asymmetry imposed by the non-alternate order of the two peripheral substituents, breaking C4 symmetry, was confirmed by X-ray and NMR studies. The newly synthesized, unsymmetrical magnesium porphyrazine revealed interesting solvatochromic properties.Figure optionsDownload full-size imageDownload as PowerPoint slide