Magnetic and photoluminescent properties of three new organic radical cation salts

•New organic radical cation salts were prepared via facile anion exchange reaction.•Three radical cation salts exhibit antiferromagnetic behaviors.•Interesting magnetic phase transition.•Three radical cation salts reveal blue photoluminescence.

Three new organic radical cation salts were prepared by exchanging perchlorate anion of 2,3′-biimidazo[1,2-a]pyridin-2′-one radical perchlorate salt with metal coordination anions. These cation salts, [H (Hbipo–)]+2· [FeCl4]2–·H2O (1), [H (Hbipo–)]+2· [MnCl4]2–(2) and [H (Hbipo–)]+·[Zn(SCN)3] –·H2O (3), were characterized by EPR and IR spectra, and their composition was demonstrated by the elemental analyses and TGA analyses. Salts 1, 2 and 3 mainly exhibit antiferromagnetic properties, however, salts 2 and 3 reveal interesting magnetic phase transition at 243 K and 65 K, respectively. Compared to 2,3′-biimidazo[1,2-a]pyridin-2′-one radical itself (green emission), salts 1, 2 and 3 display obviously blue shifted to blue emission, attributable to their low HOMO energy level caused by the protonation of N atom at imidazo[1,2-a]pyridine ring. Present work will provide new organic radical cation for the preparation of molecular materials with combination of different physical properties by using various metal coordination anions.