Synthesis, Crystal Structure And Photo–electric Property Of A Series Of Ni-Cd/Zn Heterometallic/Ni-Ni Homometallic Polymers

Twelve polymers have been synthesized by the hydrothermal methods of Ni（II）, Zn（II）,Cd（II） and Co（II） ion with pyridine-2,3-dicarboxylic acid, pyridine-2,6-dicarboxylic acid,phthalic acid, benzene-1,3,5-tricarboxylic acid and pyrazol etc. All single crystals wereobtained and determined by X–ray single crystal diffraction. The formulas of polymers arelisted as follows:（1）[NiZn（2,3-pdc）₂（H₂O）₃]_n（2）[NiCd（2,3-pdc）₂（H₂O）₃]n（3）{[Ni（pz）₄（H₂O）₂][Cd（1,3-bdc）₂]_n（4）[Ni（1,2-bdc）₂（pz）₄]（5）{[Ni₃（1,2-bdc）₃（pz）₁₂]·2H₂O}n（6）[Ni（1,2-bdc）（pz）₂H₂O]_n（7）[Ni（ppz）_0.5（mal）H₂O]_n（8）[CuCo（2,6-pdc）₂（H₂O）₅]·2H₂O（9）{[Co2（btc）（H₂O）₆]（ppz）（H₂O）}_n（10）[Co₂（btec）（H₂O）₉10)]2·2H₂O（11）[Co（bipy）₂CO₃]·NO₃·5H₂O （12）[Cd₂（2,3-pdc）₂（H₂O）]n（2,3-H2pdc=pyridine-2,3-dicarboxylic acid,2,6-H2pdc=pyridine-2,6-dicarboxylic acid,1,2-H2bdc=1,2-phthalic acid,1,3-H2bdc=1,3-phthalic acid, H3btc=benzene-1,3,5-tricarboxylicacid, H4btec=benzene-1,2,4,5-tracarboxylic acid, H2mal=malonic acid, pz=pyrazol,ppz=piperazine, bipy=2,2′-bipyridine）Structur alanalyses show that polymer （1） is Ni-Zn polymer, polymer （2） and （3） areNi-Cd polymers, complex （8） is Co-Cu complex, polymers （4） to （7） are Ni polymers,complexes （9） to （11） are Co complexes, polymer （12） is Cd polymer.All the polymers are characterized by IR, UV–Vis–NIR, surface photovoltagespectrum （SPS）, which are all compared and assigened. The main important work iscompared with the complexes of SPS that is photoelectric response. The results are presentedas follows:â‘ The dimensional structure of polymers influence the intensity of the photoelectricresponse. The more dimensional structure, the more photoelectric response. The polymers （7） and （5）exhibit3D and1D, respectively. The complex （4） exhibits a0D structure. Which may provided moretransitional ways for electron and holes, thus the intensity of SPS is （7）>（5）>（4）. Which mayprovided more transitional ways for electron and holes, thus the intensity of SPS is3D>2D>1D>0D.â‘¡The MLCT response of Ni-M hetero-nuclear is significantlt difference by theintroduction of the second metal ions. The polymer （1） is Ni-Zn hetero-nuclear, The polymer （2） is Ni-Cd hetero-nuclear. The polymer （2） is broader than the polymer （1）.Because of dispersion is deffence of d orbit in Zn/Cd.â‘¢The micro coordination enviroment of center metal ions influence the SPS. Thepolymers （5） and （6） are all with Ni（II） as central metal, while the mico coordinationenvironment is different obviously. There are six-coordinated （NiN4O2coordination mode）in the polymer （5）, and there are six-coordinated （NiN2O3O coordination mode） in thepolymer （6）. Apparently, the symmetrical of polymer （6） is lower than polymer （5）. So themico coordination environment is different resulting in the complicated response bandsaroused by d-d*transition. There are many splited photoelectric response in the polymer （6）and the rang of photoelectric response is boarder.