One-pot Synthesis and Photophysical Studies of Α-cycloamino-substituted 5-aryl-2,2'-bipyridines

A series of α-cycloamine substituted 2,2’-bipyridines 3ae’-3ce’ was obtained via the one-pot approach based on ipso -substitution of a cyano-group in 1,2,4-triazines, followed by aza -Diels–Alder reaction in good yields. Photophysical properties, including fluorosolvatochromism, were studied for 3ae’-3ce’ and were compared with α -unsubstituted 2,2’-bipyridines. In addition, dipole moments differences in ground and excited states were calculated by both Lippert-Mataga equation and DFT studies and were compared to each other. The correlation between the size of cycloamine unit and the dipole moments differences value (based on Lippert-Mataga equation) was observed. In addition charge transfer indices ( D CT , Λ , H and t ) were calculated to demonstrate influence of molecular structure on the intramolecular charge transfer degree.