Cu/Fe-mediated N(sp2)-arylation/alkenylation of pyridines with aryl-/alkenylboronic acids to yield versatile cationic materials

Abstract

Cu/Fe-mediated arylation of pyridines with arylboronic acids, featuring a low-cost catalytic system and an easy operation, is disclosed. A series of length-controllable linear (the number of aryls ranges from 2 to 6) and L-shaped pyridinium salts have been easily prepared by this N(sp²)-arylation and they show tunable fluorescence emission that is mainly tailored by the length of the N-aryl rather than C-aryl groups. Furthermore, direct N-alkenylation of sp²-nitrogen heterocycles is reported. Moreover, the AIE, pH-responsive and electrochromic properties of the relevant pyridinium salts are researched.