Synthesis, Crystal Structure and Characterization of Cu(II) and Cd(II) Coordination Compounds Based on Ligand 2-(3-(Pyridin-2-yl)-1H-pyrazol-1-yl)acetic Acid

Two novel coordination compounds $[Cu_2(pypya)_3(H_2O)_2]{\cdot}Cl{\cdot}(H_2O)_5$ (1) and $\{[Cd(pypya)(ta)_{1/2}]{\cdot}H_2O\}_n$ (2) (Hpypya=2-(3-(pyridin-2-yl)-1H-pyrazol-1-yl)acetic acid, $H_2ta$=terephthalic acid) were synthesized and characterized by single X-ray diffraction. Structure determination reveals that complex 1 and complex 2 crystallize in the triclinic system, with the P-1 space group. The asymmetric unit of 1 contains two Cu(II) ions, and their coordination modes are different. These units of complex 1 are linked together via hydrogen bonds and ${\pi}-{\pi}$ interactions, and the 3D structure of complex 1 was formed. Complex 2, a mononuclear Cd(II) coordination compound, has a 2D structure which was constructed via coordination bonds. TGA and fluorescence spectra analysis of complex 1 and complex 2 have also been studied. In addition, the geometry parameters of complex 1 have been optimized with the B3LYP method of density functional theory (DFT) to explain its coordination behavior. The electronic properties of the complex 1 and ligand Hpypya have been investigated based on the nature bond orbital (NBO) analysis at the B3LYP level of theory. The result verifies that the synergistic effect have occurred in the compound.