Synthesis,Structure And Photo-electric Property Of Transition-metal Coordination Polymers Constructed From N-heterocycle Carboxylate Ligand

Polymers with photo-electric function play an important role in the fields of photoelectric materials.The starting point of this paper is to design and synthesize polymers with photoelectric conversion properties and characterize the crystal structures and properties.Based on the data structures,explore the correlation of structures and photoelectric properties.Three series of coordination polymers were designed and synthesized by hydrothermal method with d⁶-d¹⁰transition metal ions as central metals:（1）With maleic acid and N-H heterocyclic organic molecular（piperazine,pyrazole）as precursor ligands,in situ synthesize two new type ligands（H₄L¹,H₂L²）by aza-Michael addition reaction,and seven novel polymers were generated from self-assembly reaction.This part is the innovation points of this paper.（2）Three unreported Cu（I）polymers have been synthesized with nitrogen heterocyclic organic molecules as co-ligands,with small molecules as ligands together.（3）Four Co/Cu polymers and supermolecular were synthesized with aromatic compounds and derivatives as ligands.The structures were determined by X-ray single diffraction.The formulas are listed as follows:（1）[Ni（L¹）_0.5（H₂O）₂]_n（6）[Ni₂（L²）₂（H₂O）₂]_n（11）[Co（bptc）_0.5（H₂O）]_n（2）[Co（L¹）_0.5（H₂O）₂]_n（7）[Cu₂（L²）₂（H₂O）₂]_n（12）[Co（3,4-pdc）（H₂O）]_n（3）[Zn₂（L²）₂（H₂O）₂]_n（8）[Cu₂（amp）Cl₂]_n（13）[Cu（2,6-pdc）（amp）]·3H₂O（4）[Fe₂（L²）₂（H₂O）₂]_n（9）[Cu₂（amp）（CN）₂]_n（14）{[Cu（4,4’-bipy）（H₂O）₃]（SO₄）·2H₂O}_n（5）[Co₂（L²）₂（H₂O）₂]_n（10）{[Cu Cl₂]（4,4’-H₂bpip）_0.5}_nSingle crystal structure analysis shows that polymers（1）-（7）are d⁶-d¹⁰polymers constructed from coordination bonds with 2D structures.Polymers（8）,（9）and（10）are Cu（I）polymers constructed from coordination bonds respectively with 2D,3 D and 1D structures.Polymers（11）-（14）are Co/Cu polymers or supermolecular based on aromatic compounds.Fourteen polymers are characterized by IR,UV-Vis-NIR,SPS and FISPS,XRD,TG.Based on crystal structures,compare and discuss the surface electron behavior under the inducement of visible light,and the following conclusions are preliminarily obtained.（1）There were obvious photovoltage responses for fourteen polymers under the inducement of UV-Vis light in the range of 300-800 nm,which indicates that they are provided with photo-electric conversion properties.（2）The conjugation degree of the polymer system affects the photovaltaic properties.The introduction of the conjugated group,which is beneficial to the electron delocalization,can broaden the absorption of light in the visible region and improve the probability of electron transition from ligand interior,and it is favourable to creation and transmission of photogenerated carriers,thus enhance the photovoltaic response.（3）The structure dimensions of polymers can affect photovoltaic response intensity.The high dimension provide more channels for transmission of electron/hole.High dimension polymers constructed from coordination bonds have stronger photovoltaic response signals than polymers connected with H-bonds.（4）The kinds of center metal ions and their crystal fields can affect SPS signal slightly in the polymers with the same structures.The above conclusions can provide some references for the preparation of metal-organic framework polymers with photo-electric conversion function.