Magnetic and photoluminescent properties of three new organic radical cation salts

Abstract 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 · [FeCl 4 ] 2– ·H 2 O (1) , [H (Hbipo – )] + 2 · [MnCl 4 ] 2– (2) and [H (Hbipo – )] + ·[Zn(SCN) 3 ] – ·H 2 O (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.