Synthesis And Structure Of Copper Cluster Coordination Polymers

Materials,energy,and information act as the three pillars of modern scientific development and are the material basis of our social life.As a new type of functional molecular material,coordination polymers?CPs?have good application prospects in the fields of light,electricity,magnetism,adsorption,catalysis,etc.At present,the structure of metal coordination polymers can be controlled to some extent via the crystal engineering of metal coordination polymers.Consequently,varieties of coordination polymer functional materials with good performance have been fabricated.However,the synthesis process of coordination polymers is very complicated and the understanding of the formation mechanism of coordination polymers is still immature.Hence,to achieve the goals of molecular design and directed synthesis,both in-depth research and the rich accumulation of experimental results are required..Coordination polymers usually consist of metal clusters as secondary building units?SBUs?and organic ligands as linkers.Both organic ligands and secondary building units will affect the structure or topology of the coordination polymers.Therefore,the selections of appropriate organic ligands or assembly of variable secondary building units play significant role in the molecular design strategies.In the present study,different types of phthalic acid?terephthalic acid,isophthalic acid and phthalic acid?and 2,2'-bipyridine were selected as the ligands,and Cu???was selected as the central metal.Fourcoordinationpolymers[Cu₄?bipy?₄?OH?₄?H₂O?₂]?1,4-BDC?₂·3H₂O?1??[Cu₄?bipy?₄?OH?₄?H₂O??1,3-BDC?]?1,3-BDC?·13H₂O?2??[Cu₄?bpy?₄?OH?₂?1,2-BDC?₂]·10H₂O?3??[Cu₂?1,2-BDC?₂?bipy?₂?H₂O?]·3H₂O?4??biby=2,2'-bipyridine,1,4-BDC=terephthalic acid,1,3-BDC=isophthalic acid,1,2-BDC=phthalic acid?were successfully synthesized under the normal temperature volatilization reaction conditions.The structures of the four coordination polymers were determined by single crystal X-ray diffraction.Details are as follows:?1?Three tetra-nuclear Cu??? coordination compounds have been synthesized by self-assembly of copper?II?nitrate with N/O donated bi-ligands under ammonia aqueous/ethanol mixture solution reaction.Single crystal structures were determinated by X-ray crystallogarphic analyses,which were shown that three compounds feature chair-like hydroxy-bridgedtetra-copper?II?cluster:symmetric[Cu₄?bipy?₄?OH?₄?H₂O?₂]⁴⁺in1,asymmetric[Cu₄?bipy?₄?OH?₄?H₂O??1,3-DBC?]²⁺in 2,and symmetric[Cu₄?bipy?₄?OH?₂?1,2-BDC?₂]²⁺in 3?bipy=2,2'-bipyridine and H₂BDC=benzene dicarboxylic acid?.Three bi-topic benzene dicarboxylic ligands(1,4-DBC^2-,1,3-DBC^2-or 1,2-DBC^2-)act as hydrogen bond's acceptor,monodentate terminal ligand,as well as bidentate bridging ligand,respectively.Thus,hydrogen-bonds plays the key roles to influence the formation of Cu₄-cluster···ligand hydrogen net to 2-D layer metal-carboxylate coordination polymer.?2?A dinuclear copper coordination polymer with V-shaped ligand?1,2-benzenedicarboxylic acid?and N-donor co-ligand?2,2'-bipyridine?,{[Cu₂?1,2-BDC?₂?bipy?₂?H₂O?]·3H₂O}_n,has been synthesized under the normal temperature volatilization reaction conditions.The single-crystal X-ray diffraction analysis indicates that the title compound crystallizes in the monoclinic system,sp.gr.P2₁/n with the unit cell parameters a=12.992?5??,b=20.709?7??,c=13.652?5??,and?=109.401?7?o,Z=4.The binuclear[Cu₂?1,2-BDC?₂?bpy?₂?H₂O?]clusters were linked by bridging ligands BDC^2-to form one-dimensional looped double chain.Through intermoleclular?-?stacking and hydrogen bonds between the coordination water,lattic water and free oxygen atom from carboxylate to yield a 3D supramolecular structure.