Synthesis,Structure And Surface Photo-electric Property Of Heterometallic And Homonuclear Coordination Polymers Containing L-type Ligands

Seven coordination polymers containing L-type ligands have been designed and synthesized by the hydrothermal methods of Cu^II,Ni^II,Co^II and V^V ion with cis/trans-maleic acid and containing organic functional group of N-H（1-（4-chlorophenyl）piperazine,3,5-dimethyl pyrazole and pyrazole etc）as precursor ligands.Designed and synthesized of the two kinds of Cu^II-Cd/Zn and two kinds of V^V-Co/Ni heterometallic polymers are based on the pyridyl.Based azoles,carboxylic acids mixed ligands were designed and synthesized two Co^III polymers two Cu^II complexes and a Cd^II polymer.All coordination polymers were obtained and determined by X–ray single crystal diffraction.The molecular formula of complexes are listed as follows:（1）[CuZn（L¹）₂（H₂O）₄]_n（9）{[ZnCu（1,2-bdc）₂（bipy）₂（H₂O）].3H₂O}_n（2）[CuCd（L¹）₂（H₂O）₄]_n（10）[CoV₂O₆（bipy）（H₂O）]_n（3）[NiZn（L¹）₂（H₂O）₄]_n（11）[NiV₂O₆（bipy）（H₂O）]_n（4）[Co₂（L¹）₂（H₂O）₄]_n（12）[Co（1,3-bdc）（pz）₂]_n（5）{[Co（L²）（H₂O）₂].（H₂O）}_n（13）[Co（1,3-bdc）（3,5-dime-pz）₂]_n（6）{[Ni（L³）（H₂O）₂].（H₂O）}_n（14）[Cd（1,3-bdc）（phen）]_n（7）{[Co（L³）（H₂O）₂].（H₂O）}_n（15）[Cu（tol）₂（Imh）₂（H₂O）]（8）{[CdCu（1,3-bdc）₂（bipy）（H₂O）].2H₂O}_n（16）[Cu（2,6-pdc）（Imh）]（H₂L¹=2-（1-pyrazol）-succinic acid）,H₂L²=2-（3,5-dimethylpyrazol）-succinic acid,H₂L³=2-（1-4-chlorophenyl-piperazino）-succinic acid,bipy=2,2′-bipyridine,2,6-H₂pdc=pyridine-2,6-dicarboxylic acid,3,5-dime-pz=3,5-dimethylpyrazole,1,3-H₂bdc=1,3-phthalic acid,1,2-H₂bdc=1,2-phthalic acid,pz=pyrazole,Imh=tmidazole,phen=1,10-phenanthroline,H₂tol=4-methylbenzoic acid)Structure alanalyses show that:polymer（1）-（7）were used cis/trans-maleic acid and containing organic functional group of N-H（1-（4-chlorophenyl）piperazine,3,5-dimethyl pyrazole and pyrazole etc）as precursor ligands,situ synthesis of heterometallic and homonuclear polymers containing L₁,L₂,L₃ type of novel ligands.This is the highlight of this article.（1）-（5）are 1D polymers,and bridged to 2D polymer by hydrogen bonds;（6）and（7）are 1D polymers;（8）and（9）are Cu^II-Cd/Zn heterometallic polymers,between Cu and Cd/Zn atoms bridged to 2D/1D polymer by carboxyl oxygen atom;（10）and（11）are V^V-Co/Ni heterometallic polymers,is isomorphic,all metal atoms bridged by O atoms,form 2D polymers;（12）and（13）are 1D Co^II polymers,polymer（12）bridged to 2D by hydrogen bonds;（14）is Cd^II polymer;（15）and（16）are Cu^II mononuclear complexes,and bridged to 2D and1D supramolecule by hydrogen bonds and weakly coordinating role.All the polymers are characterized by IR,UV-Vis-NIR,surface photovoltage spectrum（SPS）,which are all compared and assigened.The main important work is compared with the complexes of SPS that is photoelectric response.The results are presented as follows:1.The photo-electric properties of complexes were investigated by surface photovoltage spectroscopy（SPS）.The results of SPS show that the three complexes exhibit obvious photovoltage responses in the range of 300⁸00 nm,which indicates that they all possess certain photo-electric conversion properties.2.When the complex have similar structure,the valence and coordination numbers of the central metal ion are the same,inside the SPS of this polymer,the conjugate of ligand is better,the bands are stronger.As the polymer（4）,（5）and（7）,they are six-coordinated.Coordination polymer（4）contains a pyrazole ring which with a rigid planar conjugated structure.While inside the 3’5-dimethyl-pyrazolyl of（5）,there are 2 methyls as the electron donating.They form a better conjugation with the pyrazole ring,so that make the conjugated of（5）is stronger than（4）.And in the（7）has the ligand of 1-（4-chlorophenyl）piperazinyl,but its conjugated is poor.As we know,if the conjugation is better,can provide more channel for electronic transmission,and the SPS signal is stronger.So the strength of ligand conjugated is（5）>（4）>（7）,and SPS band intensity is（5）>（4）>（7）.Polymer（12）and（13）are also consistent with this conclusion.3.Inside of the homonuclear coordination polymers,the response bands occurred to broaden and strengthen due to the introduction of various metal ions（such as Zn/Cd）.The polymer（1）is Cu-Zn hetero-nuclear,（2）is Cu-Cd hetero-nuclear.The MLCT response of polymer（2）is broaden and strengthen than the polymer（1）.It may be because of the introduction of Zn²⁺and Cd²⁺in different periods,for the dispersion level in the space,normally the 3d orbit of the Zn²⁺which in the fourth period is lower than 4d orbit of Cd²⁺which in fifth period.Polymer（8）and（9）are also consistent with this conclusion.4.Complexes of the same metal center,but the difference was the central metal surrounding micro environment,the number and range of the band of SPS has significant impact.For example:the Cu^II complexes,complexes（15）for five-coordinated,at the approximate C_4v field,d-d*transition absorption bands of Cu²⁺:E→B₂,E→A₁.Polymers（1）-（2）for six-coordinated,at the approximate Oh field,d-d*transition absorption bands of Cu²⁺:²E_g→²T_2g;And the polymers（4）and（5）are all with Co^II as central metal,There are six-coordinated,coordination mode were CoN₂O₄ and CoNO₅.Apparently,the symmetrical of polymer（5）is lower than polymer（4）.So the response bands aroused by d-d*transition of（5）has small splitting strength.The band of SPS significantly broadened.