Isostructural metal-anion radical coordination polymers with tunable phosphorescent colors (deep blue, blue, yellow, and white) induced by terminal anions and metal cations

摘要

Five phosphorescent metal-anion radical coordination polymers based on a new anion radical ligand generated by in situ deprotonation of a stable zwitterionic radical are described. The N,O,N-tripodal anion radical ligand links metal cations, which leads to five isostructural coordination polymers, [M_3(bipo-.)_4(L)_2]_n (M=Cd or Mn, Hbipo~-.=2,3′-biimidazo[1,2-a]pyridin-2′-one, L=Cl~-, HCOO~- or SCN~-). The isostructural coordination polymers exhibit novel one-dimensional spirocycle-like structures. Three isostructural Cd~II coordination polymers display unusual phosphorescent color changes (blue, yellow, and white) induced by terminal anions. Significantly, the Cd~II coordination polymer with terminal Cl~- possesses moderate quantum yield, and shows a bright white-light phosphorescence emission, which is independent of excitation wavelength and can even be excited by visible light. Upon adjusting the metal cation to Mn ~II, two isostructural Mn~II coordination polymers reveal deep-blue-light phosphorescence emissions that are independent of terminal anions. As radical-based coordination polymers, some of them show antiferromagnetic interactions between radical species or radical and metal center. True colors: Five isostructural metal-anion radical coordination polymers, [M_3(bipo~-.)_4(L)_2] _n (M=Cd or Mn, Hbipo~-.=2,3′-biimidazo[1,2-a]pyridin- 2′-one, L=Cl~-, HCOO~-, or SCN~-), are described. A bright white-light and a deep-blue-light phosphorescent coordination polymer with moderate quantum yield can be obtained through adjusting the terminal anions and metal cations, respectively (see picture). Such coordination polymers also display antiferromagnetic properties.