Influence of N-donor substituents on physicochemical properties of phenanthro[9,10-d]imidazole derivatives

In this study, the synthesis and physicochemical properties (thermal, electrochemical and optical) of three phenanthro[9,10-d]imidazole derivatives with N-donor substituents ( PI-1 - PI-3 ) was presented. All compounds were obtained by condensation reactions with a yield in the range of 61–70%. Their structure was confirmed by NMR spectroscopic methods ( 1 H, 13 C, H–H COSY, H–C HMQC and H–C HMBC). The synthesized derivatives were characterized by high thermal stability (above 300 °C). Two of them ( PI-1 and PI-3 ) showed a fully reversible oxidation process, which allowed detailed spectroelectrochemical and electrochemical studies. Absorption and emission properties were tested in four solvents of different polarity. These compounds showed high quantum yields in the range from 18 to 80%. Studies on physicochemical properties have been extended to include detailed theoretical considerations. • A series of phenanthro[9,10-d]imidazole derivatives with N-donor substituents were investigated. • All derivatives were showed high thermal stability. • These compounds were characterized by high quantum yields in the range from 18 to 80%. • Detailed theoretical calculation were performed for electrochemical and photophysical studies.