The Study Of Metal-Organic Coordination Polymers And Properties Based On Multicarboxylic Acid Ligands

Metal-organic coordination polymers?CPs?are a class of composite materials with dual characteristics of organic materials and inorganic materials,which has shown great potential value in many fields such as fluorescence sensing,catalysis,biomedicine,magnetism,energy storage,and gas adsorption.Two aromatic multicarboxylic acid ligands?terphenyl-3,3",5,5"-tetracarboxylic acid/2,4-di?2',5'-dicarboxylphenyl?benozoic acid?and two nithogen heterocyolic multicarboxylic acid ligands?3,5-di?3',5'-dicarboxylphenyl?pyridine/3,5-Di?2?,5-dicarboxylphenyl?pyridine?were chosen as main ligands in this work..Guided by the principle of self-assembly and mixed ligand strategy,18 CPs materials were successfully prepared under solvothermal or hydrothermal conditions.And then the structure and properties of the CPs were further studied.The specific research contentes are as follows:?1?Herein,eight novel CPs were successfully synthesized by the self-assembly of Cd?II?/Co?II?/Mn?II?ionswithterphenyl-3,3",5,5"-tetracarboxylicacid/2,4-di?2',5'-dicarboxylphenyl?benozoic acid under solvothermal conditions.Except that CPs5 has a two-dimensional layered network structure,the other seven CPs all have three-dimensional frameworks.It contains two pairs of heteromorphic CPs?1 and 2,6 and 8?,which are obtained under the same reaction conditions only by modulating the metal source.In addition,the structural comparison shows that the difference in the coordination modes of H₅DDCP is the main reason for the difference in structures of 6 and 7.And different coordination modes of ligand is due to the difference in pH of the reaction system.?2?Based on the unique advantages of bifunctional ligands in the construction of the CPs,two nithogen heterocyolic multicarboxylic acid ligands of 3,5-di?3',5'-dicarboxylphenyl?pyridine and 3,5-Di?2?,5-dicarboxylphenyl?pyridine were selected as the main ligands.By adjusting the metal source,the reaction temperature,the type of solvent,or the introduction of a second ligand,10 kinds of CPs were successfully constructed.Among them,a pair of two-dimensional heterogeneous CPs?9 and 10?were constructed using H₄DCPP and Co?II?/Ni?II?ions,respectively.Since water molecules occupy multiple coordination sites,the dimensions of the CPs are relatively low.H₄DDPP and Cd?II?/Zn?II?were used to construct a pair of three-dimensional isomorphic CPs?17 and 18?.Interestingly,13 and 14 are two three-dimensional copper-based CPs obtained by only changing the reaction temperature.The difference in reaction temperature results in the structural diversity of the CPs during self-assembly.?3?Firstly,the structure of the CPs 1¹8 was characterized by single crystal diffraction,thermogravimetry,powder diffraction and elemental analysis..Based on the good fluorescence characteristics of Zn/Cd-based CPs,the fluorescence recognition properties were studied.Except 15,the other eight CPs can be used as sensitive water-phase sensors for Fe³⁺and TNP,and show good cycling and anti-interference.And the K_svv of 6/18 of Fe³⁺and TNP are both on the order of 10^-5.Gas adsorption experiments show that the adsorption amounts of6 for CO₂ are 48.5 cm³ g^-1?273 K,1 bar?,which has a higher CO₂ capture capacity than CH₄.At the same time,IAST shows that the selectivity of CO₂ to CH₄ at 298 K and 1 bar is 54(V_CO2:V_CH4=5:95)and 27(V_CO2:V_CH4=50:50),respectively.