Synthesis, Characterizations And Biological Activities Of Coordination Compounds With Pyrazine Derivatives As Ligands

In recent years, metal-organic supramolecular complexes have become one of the hotspots of coordination chemistry because of their variety of structuresits potential applications in the fields of optical, magnetic, catalysis, adsorption and molecular recognition. In this paper, two N-containing heterocyclic substituted ligands Hpytyba and H pypymba derivative from pyrazine were selected. The two ligands which contain a variety of N atom coordination sites were used react with various transition metal ions to build metal-organic coordination compounds by crystal engineering self-assembly principles. The crystal structure of the complexs were first determined by X-ray crystal diffraction method, then characterizaed by elemental analysis, thermal analysis, as well, the antibacterial and anti-oxidation activity of the complexs were also tested. All these experiment provided valuable information for applications in medicine, materials science and so on. In other words, it can also provide preliminary theoretical and experimental basis for the development of metal-based supramolecular drugs.In the synthesis process of metal-organic complexes, under different conditions, using diffusion and hydrothermal method we synthesized four complexes which have not been reported:{[Mn(pytyba)(H2O)3]·2H2O}n(1),{[Zn(pytyba)(H2O)3]’4H2O}n(2),[Cd2(pypymba)2(CH3COO)2(H2O)2]n(3) and [Cd(pypymba)2-H2O] n(4). Compounds1and2have the same coordination mode, both O and N of the ligand Hpytyba and the other three free water molecules coordinated with the metal ions and on and formed one-dimensional chain structure by M—O coordination bonds, then the three-dimensional supramolecular structure were formed by hydrogen bonds and π--π interactions. Although compounds3and4were synthesized by the same ligands and metal ions, but they have different coordination modes, In complex3, the compounds formed supramolecular structure rely on C——H…O weak hydrogen bonds, but in complex4, one-dimensional chain was formed by Cd-O coordination bonds, two-dimensional network structure was formed by C(28)—H(28)…O(2) weak hydrogen bonds, and three-dimensional structure was formed by C(7)—H(7)...O (5) weak hydrogen bonds.Furthermore, by analysising the structure of the ligand Hpytyba and Hpytyba we also tried to use5-methylpyrazine-2-carboxylic acid reacting with aminopyridine to preparation amide compounds using DCC as dehydrating agent and DMAP as catalyst under room temperature thus got two pyrazine amide derivatives. At last, silica gel column was used to separate the target product and identified the structure by HNMR methods.