Abstract
Three new complexes, [Cu(II)L]n (1), [Co(II)L(H2O)]n (2), and [Ni(II)L(DMF)(H2O)2] (3), where H2L = [2-(2-(3-methyl-5-oxo-1-phenyl-1H-pyrazol-4(5H)-ylidene) hydrazinyl) benzoic acid], were synthesized and characterized via elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Single-crystal X-ray diffraction analysis revealed that 1, 2, and 3, formed by H2L with metal nitrate, have zigzag chain, helical chain, and mononuclear structures, respectively. The luminescence spectra study reveals that 1 has two emission peaks at 470 and 540 nm, which are attributed to intraligand charge transfer and ligand-to-metal charge transfer fluorescent emission, respectively. In 2 and 3, almost 100% fluorescence emission quenching is observed.