Synthesis,Structure And Properties Of Co-Coordinated Metallic Supramolecular Compounds Based On Dicarboxylic Acids

Coordination polymers（CPs）,with their rich and fascinating structures,have shown great interest in many fields such as magnetism,catalysis,gas adsorption and separation.In recent years,using the principles of crystal engineering to design and assemble functional coordination polymers has become one of the most active research fields in materials science and supramolecular chemistry.Multiple coordination sites of polycarboxylic acid ligands can participate in coordination at the same time,and can act as hydrogen bond acceptors or donors according to the degree of deprotonation,improve structural stability,and are good structural blocks for building coordination polymers;The N atom of polypyridine ligands can chelate with metal ions,often used as co-ligands to further enhance the stability of the crystal structure,and also plays a crucial role in the construction of metal coordination polymers.In this paper,three dicarboxylic acid ligands（1,4-naphthalenedioic acid,fumaric acid,1,4-terephthalic acid,）and two polypyridine ligands（4,5-diazafluoren-9-one,o-phenanthroline）,and self-assembled with Co（Ⅱ）to obtain seven coordination supramolecular compounds.[Co（dafo）₂（Me OH）₂]（NO₃）₂（1）[Co（dafo）₂（Et OH）₂]（NO₃）₂（2）[Co（BDC）（phen）（H₂O）]n·DMF（3）[Co（BDC）（Phen）（H₂O）]n（4）[Co（BDC）（Phen）₂]n·DMF（5）[Co（BDC）（DMSO）]n（6）[Co（NDC）（DMSO）]n（7）（1,4-Naphthalenedioic acid=H₂NDC,fumaric acid=fuma,1,4-terephthalic acid=H₂BDC,4,5-diazepine-9-one=dafo,1,10-o-phenanthrene roline=phen,N,N’-dimethylformamide=DMF,dimethyl sulfoxide=DMSO）The crystal structures of the seven coordination polymers were characterized by single-crystal X-ray diffraction,as follows:（1）Two mononuclear ligands were self-assembled from the polypyridine ligand4,5-diazafluoren-9-one（dafo）and Co（Ⅱ）in methanol/ethanol system by solvothermal synthesis.Molecularcompounds[Co（dafo）₂（Me OH）₂]（NO₃）₂（1）,[Co（dafo）₂（Et OH）₂]（NO₃）₂（2）.The single crystal data results show that the two complexes have similar structures,and the thermal stability of compound 1 was analyzed by synchronous thermal analyzer.（2）Under the condition of solvothermal synthesis,select 1,4-terephthalic acid（H₂BDC）and 1,10-phenanthroline（phen）to react with Co（Ⅱ）,by changing the reaction solvent,the ratio of reactants and the reaction temperature,three one-dimensional chain complexes[Co（BDC）（phen）（H₂O）]n·DMF（3）,[Co（BDC）（Phen）（H₂O）]n（4）,[Co（BDC）（Phen）₂]n·DMF（5）.The crystal structures of the three complexes were detected and analyzed by X-ray single crystal diffraction technique.The complexes 3-5 were all composed of asymmetric mononuclear clusters as secondary structural units（Secondary Structural Unit,SBU）,connected by BDC^2-composition,in which Co²⁺in complexes 3 and 5 is hexacoordinated,and Co²⁺in complex 4 is pentacoordinated.The change of the reaction solvent and reaction temperature affects the coordination mode of the metal and the coordination mode of the ligand.Then,the changes of bond length,bond angle and interaction force of the complex are affected,and finally three complexes with different structures are obtained.The complexes 3 and 4 were characterized by X-ray powder diffraction,and the thermal stability of complex 4 was analyzed by synchronous thermal analyzer.（3）1,4-terephthalic acid（H₂BDC）,1,4-naphthalenedioic acid（H₂NDC）in N,N′-dimethylformamide/dimethylsulfoxide system by solvothermal synthesis)and Co（Ⅱ）were self-assembled to obtain two novel three-dimensional complexes[Co（BDC）（DMSO）]n（6）,[Co（NDC）（DMSO）]n（7）.The crystal structure was characterized by X-ray single crystal diffraction technique.The coordinated DMSO in complex 6 occupies the pores and appears to be non-porous.Complex 7 has three different pores.Analysis and other techniques were characterized.