Synthesis, Crystal Structures And Properties Of Transition Metal Coordination Polymers With Sulfydryl-containing Heterocyclic Ligands

In the past few decades, the study of supramolecular chemistry and crystal engineering based upon the spontaneous self-assembly of metal ions and bridging organic legends has drawn pronounced interest. Against this background, spectacular examples of supramolecular architectures organized by means of covalent bonds, hydrogen bonds,Ï€-Ï€interactions, or their combination in different ways have been reported. However, the influencing information on supramolecular assemblies is not yet well understood. In addition, as one of the important researches of coordination chemistry and organic chemistry, the in situ reaction of solvent (water) thermal conditions have been widely used in the discovery of new organic reactions, describability of reaction mechanism and the synthesis of novel coordination compounds, in particular, is used for the synthesis of complex that are difficult to get at the direct response with organic ligands.We use three sulfydryl-containing heterocyclic ligands:5-(4-pyridyl)-1H-1,2,4-triazole -3-thiol (H₂L₁), 2-Mercaptonicotinic acid (H₂L₂) , 2-Amino-5-mercapto-1,3,4-thiadiazole (H₂L₃). They react with transition metal respectively and gain 12 coordination compound:[Co^<sup>â…¡(L1)(H₂O)]n (1), [Co^<sup>â…¡(L1)(H₂O)]n (2) , [Cd^â…¡(L1)(H₂O)]n (3) , [Cd^â…¡(L1)]n (4) ,{[Zn^â…¡₂(L₂)₂.(H₂S)(H₂O)]·H₂O}₂ (5),{[Zn^â…¡₂(L₂)₂(H₂O)₂]·2H₂O}₂ (6), [Zn^â…¡(L2₎4(H₂O)]_n (7), [Zn^â…¡(L₂)₂]_n (8), [Zn₃(L₂)₂(HS-)₂2H₂O]_n (9), [Zn^â…¡(L4)2]n (10), [Cd^â…¡(L₄)2]_n(11), {[Cd^â…¡2(HL₄)₂(L4)].H₂O}_n (12). The coordination compounds has been characterized and researched.Complexes 1-4 were synthesized by the reaction of H₂L1 and metal salt at hydrothermal conditions. The complex 1 is 2D structure, 2 is 2-fold interpenetration 3D structure. They are the supramolecular isomerism. Complexes 3 and 4 are 3D structure and the pseudo-supramolecular isomerism. The different structures indicate that the pH plays a significant role in the construction of supramolecular isomerism. The reason is further explained.Complexes 5-9 were synthesized by the reaction of H₂L2 and zinc nitrate at various hydrothermal conditions. Their structures and fluorescence properties are analysed, the relationship between crystal structures and fluorescence properties is explored. Complexes 5 and 6 are tetranucleate rings. Complexes 7, 8 and 9 are one-dimensional structures based on the basic unit-tetranucleate, binucleate and mononuclear respectively. The relationships between structures and fluorescence properties are further concluded.Complexes 10-12 were synthesized by the reaction of H₂L₃ and zinc chloride and cadmium iodide at hydrothermal conditions. Complexes 10 and 11 are 1D chains, 12 is 2D structure. Their structures and fluorescence properties are analyzed and the reaction mechanism is explored.