Design,Synthesis And Properties Of Complexes Based On Novel Pyrazole Derivatives

Recently,the designs and synthesis of complexes based on pyrazole derivatives have received wide attention because of their intriguing structural topologies and potential applications in diverse fields such as coordination chemistry,fluorescent probes,magnetic materials,ion exchange and supercapacitors.Pyrazole carboxylate ligands are often selected as functional ligands to construct a series of metal coordination polymers with novel structures and unique functions for their abundant N,O donors.Accordingly,12 novel complexes reported in this paper were designed and synthesized by the self-assembly with the transition metal ions(Cd²⁺,Co²⁺,Mn²⁺,Zn²⁺)and main group metal ion(Pb²⁺)using pyrazole carboxylate ligands as the main organic ligands.All of them were structurally characterized via elemental analysis,FT-IR spectroscopy,single-crystal X-ray diffraction analysis and X-ray powder diffraction.In addition,the solid-state fluorescence and electrogenerated chemiluminescence（ECL）behavior of these complexes were investigated and thermal stability as well as magnetism was confrmed.The specific research contents are as follows:（1）By employing 5-（pyridine-3-yl）-1H-pyrazole-3-carboxylic acid（H₂PPC）as functional ligand,seven complexes（1–7）have been prepared via solvothermal reation with the transition metal ions(Cd²⁺,Co²⁺,Mn²⁺)and main group metal ion(Pb²⁺),respectively:[Cd（HPPC^-）₂（H₂O）₂]_n（1）,[Cd（HPPC^-）I]_n（2）,[Pb（HPPC^-）Cl]_n（3）,[Pb（HPPC^-）（H₂O）Cl]（4）,[Co₂（HPPC^-）₄（4,4’-bipy）]_n（5）,{[Co（HPPC^-）₂]·[Co₂（4,4’-bipy）（H₂O）₄]·(SO₄^2-)₂·2H₂O}_n（6）,{[Mn（HPPC^-）₂]·（4,4’-bipy）·5H₂O}_n（7）.Complex1 is a 3D MOF,complex 4 shows 0D binuclear monomolecular structure,complexes2–3,5–7 are 2D networks.The solid-state fluorescent properties of complexes 1–4 are investigated and the results show that these novel complexes can be used as potential luminescent materials.ECL studies indicate that the maximum luminous intensities of complexes 1–6 are 1110,1049,2085,452,2969 and 897 a.u.,respectively.They show good cyclic stability and may provide useful guidance for the design of novel electrochemiluminescent materials.Hirshfeld surface analysis reveals that complex 1is supported mainly by H···H and O···H contacts.Moreover,the N₂ adsorption measurement of 1 reveals that this MOF is a kind of mesoporous material which the pores fall into the size range from 2 to 42 nm and average pore diameters are found to be 9.9 nm.（2）By employing 5-（pyridine-4-yl）-1H-pyrazole-3-carboxylic acid（H₂ppza）as functional ligand,five complexes（8–12）have been prepared via solvothermal reation with the transition metal ions(Co²⁺,Cd²⁺,Zn²⁺,Mn²⁺),respectively:[Co（Hppza^-）（H₂O）Cl]_n（8）,[Cd（Hppza^-）（H₂O）I]_n（9）,[Zn（Hppza^-）₂]_n（10）,[Zn（Hppza^-）₂（H₂O）₂]_n（11）,[Mn（Hppza^-）₂（H₂O）₂]_n（12）.Complex 8 is a 3D MOF,complex 9 shows 1D double-chains structure,complex 10 is a 2D network,complexes11–12 are 0D monomolecular structures.The solid-state fluorescent properties show that complexes 9–11 with d¹⁰ electron configuration tend to exhibit excellent luminescence properties.ECL studies indicate that the maximum luminous intensities of complexes 8–12 are 0.16、0.09、0.07、1.62、0.10 a.u.,respectively.They show good cyclic stability and may provide useful guidance for the design of novel electrochemiluminescent materials.Furthermore,magnetic measurement of 3 shows weak ferromagnetic coupling with the decrease of temperature from 8 to 30 K and antiferromagnetic interaction among Co ^II ions.