Syntheses,Crystal Structures and Fluorescence Properties of Zn(II) Complexes with Pyrazolone Derivatives

Abstract   N-(1,3-Diphenyl-4-benzal-5-pyrazolone)-salicylidene hydrazone(H₂L ¹ ) and its zinc complex Zn(HL ¹ )₂ · 2CH₃OH (1) have been synthesized and characterized by elemental analyses, IR spectra, thermal analyses and single-crystal X-ray diffraction studies. The X-ray diffraction analyses of the complex Zn(HL ¹ )₂ · 2CH₃OH (1) and the known compound Zn₄(L ² )₄ (2) (H₂L ²  = N-(1,3-diphenyl-4-phenylethylene-5-pyrazolone)-salicylidene hydrazone) show that different acyl groups in position 4 of pyrazolones may lead to the different coordination mode of the ligands and distinctive structures of the same central metal Zn(II) complexes, of which 1 is a mononuclear complex while 2 is a tetranuclear complex. Meanwhile, two Zn(II) complexes have different thermal stabilities and fluorescence properties. Graphical Abstract        

Synthesis,Properties, and Crystal Structures of Copper(II) Di-(2-picolyl)amine Complexes Containing Inorganic Salts

Abstract These complexes have been characterized by X-ray crystallography, spectroscopic, and cyclic voltammetry. In 1, the copper(II) ion has a distorted square-pyramidal geometry with three nitrogen atoms of the dpa ligand and two oxygen atoms of the nitrate anions. The crystal structure of 2 shows that the copper(II) ions are bridged by tp anion to form a dinuclear complex, in which each copper(II) ion exhibits a distorted square-pyramid with three nitrogen atoms of the dpa ligand, water molecule, and the oxygen atom of the bridging tp ligand. Cyclic voltammetric data indicate that 1 undergoes irreversible one-electron oxidation to the Cu^III and reversible one-electron reduction to the Cu^I, while 2 gives one reversible oxidation and two reversible and irreversible reduced processes. The electronic spectra and redox potentials of the complexes are influenced significantly by the anionic ligands. Graphical Abstract The reaction of [Cu(dpa)Cl₂] with K(NO₃)₂ and Na₂tp yields mononuclear and dinuclear copper(II) complexes [Cu(dpa)(NO₃)₂] (1) and [Cu₂(dpa)₂(H₂O)₂(μ-tp)](tp)·6H₂O (2) (dpa = di-(2-picolyl)amine, tp = terephthalate).