Synthesis,Structure And Properties Of Polymers Based On Aromatic Carboxylic Acid Monomers

At present,carboxylic acid ligands are widely used in the design and synthesis of metal organic complexes and drug cocrystal.The strong ability and the flexible mode of coordination lead to forming complex and diverse targets products.In addition,the aromatic carboxylic acid ligands are also easier to form hydrogen bonds,?-? stacking and other interaction forces.The complexes can produce from zero to three-dimensional space structures.So they play a important role in the gas adsorption,catalysis,light and other fields.Based on these application,pyrazine-2,3-dicarboxylic acid was chosen as the ligand to react with different metal ions to obtain two metal-organic complexes.The single crystal structure was analyzed by X-ray single crystal diffraction.Elemental analysis,Fourier transform infrared spectroscopy(FTIR),thermogravimetric analysis(TG)and other methods were used to characterize the complexes.At the same time,complexes 1(Zn,pyrazine-2,3-dicarboxylic acid)were subjected to solid fluorescence test.The synthesized complexes have a chain structure in the a-axis direction and extend in parallel to the b-axis and c-axis through the coordination bond O-Zn-O to form a three-dimensional structure.The results show that the complexes have two distinct mass degradation at 157 ? and 283 ?.The results show that the complexes of the complexes are cleaved at 157 ?,and the complexes decompose at 323 ?.Compared with the ligand pyrazine-2,3-dicarboxylic acid,the stability of the complex increased obviously.The complex emission wavelength is 205 nm and the maximum emission wavelength is 472 nm.The fluorescence of the complex is not quenched by the common metal ions.In addition,the complexes of manganese and pyrazine-2,3-dicarboxylic acid were synthesized.The crystal of the complex was cubic,but the single crystal was not obtained.The crystal structure was not clear.The results of thermogravimetric analysis showed that the complex had a significant decrease in mass at 118 ? and 343 ?.At 118 ?,the coordination of water molecules in the complex,at 343 ?,the complex decomposition,compared with the ligand pyrazine-2,3-dicarboxylic acid stability increased significantly.The above two complexes have good chemical stability,do not dissolve in water and common organic solvents.On the other hand,5-sulfosalicylic acid(SSA)and 2,3,5,6-tetramethylpyrazine(TMP)were selected as raw materials.SSA-TMP cocrystal was synthesized by three methods.The crystal structure of SSA-TMP was measured by single crystal X-ray diffraction,and the space group(Z = 8)of Pbac(61)was orthorhombic.There are lamellar structures in SSA-TMP cocrystal,and SSA and TMP molecules form SSA plane and TMP layer,respectively.Both planes are parallel to ac-plane.The SSA layer forms a hydrogen bond network,and two S = O coplanars of the sulfo groups are involved in the formation of hydrogen bonds.S = O forms a hydrogen bond with the hydroxyl group in the carboxyl group of an adjacent SSA molecule;H on the benzene ring skeleton carbon with the sulfo group has a weak effect with the O in the carboxyl group to form a hydrogen bond,An irregular nine-ring,the nine-ring along the c-axis direction,the formation of SSA one-dimensional chain structure.The other S = O forms a hydrogen bond with the hydroxyl groups of the adjacent SSA molecule,and is arranged along the c-axis direction.Due to the directionality of the hydrogen bonds,the adjacent two SSA chains are arranged in opposite directions.The chains are arranged along the a-axis to form a two-dimensional planar structure parallel to the ac-plane.In the TMP layer,each TMP molecule and the adjacent TMP molecules are relatively weak,mainly the formation of C-N bond.Interaction between SSA layer and TMP layer.SSA molecules and TMP molecules have different degrees of overlap,the distance between the two layers of about 0.35 nm.there is a significant ?-? stacking effect.In addition to the existence of ?-? stack,there are hydrogen bonds.This hydrogen bond connects the SSA molecular layer and the TMP molecular layer.The two molecular layers are arranged alternately along the b-axis direction to form a three-dimensional network structure of SSA-TMP cocrystal.The cocrystal was further characterized by infrared spectroscopy and thermogravimetric analysis.The thermogravimetric analysis showed that the complex was decomposed at 285? The solubility and volatility of SSA,TMP and SSA-TMP cocrystal were compared.Compared with TMP,cocrystal had higher solubility and lower volatility.TMP as a drug used in the presence of insoluble in water,sublimation,heat instability characteristics,and the formation of cocrystal after SSA increased solubility,reduced sublimation,improved thermal stability,cocrystal formation of TMP drugs With the formulation improvements provide a possibility.