Tuning of photophysical, photo- and electrochemical properties of unsymmetrical D-A

To date, donor-acceptor compounds became widely used for various applications, but in many cases fine-tuning of electronic, optical, and electrochemical properties is required. For this purpose, unsymmetrical diimides 4a-c containing one cymantrenyl fragment were obtained in the work using a one-pot competitive imidization. The study of photochemical behavior by IR, NMR, UV-Visible spectroscopy and cyclic voltammetry showed that during photolysis, chelates 5a-c with the Mn-O bond of the nearest imide fragment formed. It was found that thermo-induced ligand exchange occurred in the presence of external ligands, the rate of which depended on the nature of the organic substituent at 2N. For tri- and dicarbonyl complexes, this organic fragment acted as an electron donor. It was shown that the optical and electrochemical properties of asymmetric diimides can be varied both by ligand exchange and by changing the substituent at the second nitrogen of the diimide fragment. Also, the HOMO-LUMO energy gap for chelates 5a-c (1.22-1.30 eV) decreased by 2 times compared to 4a-c (0.56-0.7 eV). Thus, the D-A