Structure regulation, fluorescence and explosive identification of cadmium(II) complexes based on 4,5-imidazoledicarboxylic acid ligand

Abstract

Three new Cd(II) complexes containing 4,5-imidazoledicarboxylic acid (H3IDC) ligand, [Cd(H2IDC)2(H2O)3]·H2O (1), Li2[Cd8(H2IDC)6(HIDC)6]@H2O (2), {[Cd(HIDC)(BBM)]·H2O}n (3) (BBM = 2,2-(1,4-butanediyl)bis-1,3-benzimidazole) have been hydrothermally synthesized under the same conditions and structurally characterized. The compounds show unprecedentedly high structural diversity. Compound 1 is a mononuclear, whereas complex 2 forms a body-centered cubic ion cluster when introducing LiOH·H2O into the reaction system. Complex 3 shows a three-dimensional structure while the bridging ligand BBM was added to the reaction system of complex 1. The degree of H3IDC deprotonating is significant in determining structural diversity. Solid-state fluorescence studies show that the order of solid fluorescence intensity of the three complex is 2 >3 >1. In addition, complex 3 can highly sensitive sense 2,4-dinitrotoluen (2,4-DNT) and 2,4,6-trinitrophenol (TNP) through luminescence quenching effect, the quenching constants are up to 3.6 × 104 M−1 and 1.9 × 105 M−1.