Luminescent monomeric and polymeric cuprous halide complexes with 1,2-bis(3,5-dimethylpyrazol-1-ylmethyl)-benzene as ligand

Abstract

Reaction of cuprous bromide with equimolar amounts of 1,2-bis(3,5-dimethylpyrazol-1-ylmethyl)-benzene (dpb) affords a mononuclear three-coordinated complex [CuBr(dpb)] (F2) with dpb acting as a chelating ligand. In contrast, using cuprous iodide instead under the same conditions gives the polymeric compound [Cu2I2(dpb)]n (F1) which contains double-bridging iodine atoms. The complexes were characterized by element analysis and 1H NMR spectroscopy, and the crystal structures were determined by single-crystal X-ray diffraction methods. The Cu(I) complexes are luminescent in the solid state at ambient temperature. Intense orange emission for complex F1 is observed, with maxima at 593nm, probably ascribed to a combination of a halide-to-metal charge transfer and copper-centered d→s, p transitions. F2 exhibits a blue photoluminescence, with emission maximum at 515nm, assigned to metal-to-ligand charge-transfer excited states, probably mixed with some halide-to-ligand characters.