Two new Ln/Ag heterometallic-based conversion phosphors constructed by 1H-benzimidazole-5,6-dicarboxylic acid

Abstract

Two new heterometallic coordination polymers [HoAg(Hbidc)₂(H₂O)₂]_n·(H₂O)_n (1) and [EuAg(Hbidc)₂(H₂O)₄]_n·(H₂O)_n (2) (H₃bidc = 1H-benzimidazole-5,6-dicarboxylic acid) have been synthesized at hydrothermal conditions and characterized by elemental analysis, FT-IR, TG analysis, single-crystal X-ray diffraction and powder X-ray diffraction. Single-crystal X-ray structural analysis revealed that complex 1 possesses a 3D framework with a (3,7)-connected {3·4·5}{3²·4³·5⁶·6⁶·7³·8} topological network. Complex 2 displays a 2D network with 3-connected {4.8²} topology. The luminescent properties of 2 were investigated in detail and its possible use as a conversion phosphor in white light-emitting diodes was evaluated. The complex shows bright red Eu³⁺ emission upon excitation at 400 nm due to a low-lying charge transfer state. The thermal quenching is already significant at room temperature.