Structural Design And Conductivity Of Metal Nitrogen Heterocyclic Coordination Polymers

Coordination polymers have attracted extensive interest for their promising application in gas storage and separation,sensors,and photocatalysis.due to the insulating properties of the coordination polymers,their applications are hindered in fuel cells,photovoltaic devices.in recent years,the design and synthesis of coordination polymers with tunable conductance properties has been one of the research hotspots.due to the good conjugated nature of the aza-macrocyclic ligands,4'-?4-pyridyl?-2,2':6',2''-terpyridine?PYTPY?and N,N'-di?m-aminobenzoic acid?-1,4,5,8-Naphthalene diimide?H₂L?were used to construct five novel coordination polymers with Cd,Zn,Co,Ni,Pb ions here.and those conductivity performance were characterized:1.A one-dimensional chain-coordination polymer 1[Cd?PYTPY??TDC?]was synthesized under hydrothermal conditions using a nitrogen heterocyclic ligand?PYPTY?and2.5-thiophene dicarboxylic acid and CdCl₂?2.5H₂O.due to the distance between the carboxylic acid oxygen atom of the thiophene dicarboxylic acid ion and the nitrogen atom in the PYTPY ring is 2.952?1??-3.453?1??,which met the conditions for electron transfer between molecules in the compound.Therefore,compound 1 changed color from light yellow to dark yellow under light stimulation.due to the electron transfer involved in the photochromic process,we characterized the single crystal conductance characteristics of compound 1 before and after illumination.the results showed the conductivity of the sample before illumination is higher than that after illumination,compound 1 is an interesting photoconductive switch.2.compound 2[Zn?L??2H₂O]was synthesized using a typical n-type organic semiconductor material NDI derivative?H₂L?as ligand and Zn?NO₃?₂?6H₂O by solvothermal method.when compound 2 was stimulated by external light,the color of the crystal changed from yellow to dark brown.due to the photochromism process involves the electron transfer and free radicals,and the distance between the H₂L ligand of adjacent chains is 3.5246?1??,which can generate a strong?-?force.the I-V curves characterization of compound 2 before and after illumination showed that the conductivity of the compound 2 increased after illumination,and the photochromic reaction was coupled with the conductivity property.3.Two nitrogen heterocyclic coordination polymers compound 3[Co?NDC??PYTPY?]and compound 4[Ni?NDC??PYTPY?],were synthesized by CoCl_2?6H₂O?for 3?,NiCl_2?6H₂O?for 4?,1,4-naphthalene dicarboxylic acid?H₂NDC?and PYTPY using hydrothermal method.the single crystal structure characterization showed that the crystal structures of compound 3 and compound 4 were the same,but the metal central ionic radius was different.conductance test showed that in the structure of compound 3 and compound 4,the larger radius of metal central ionic was,the closer the electron transport distance was,so conductive properity would be better.4.An novel iodine-lead coordination polymer compound 5[Pb₃I₆?PYTPY?₂]was synthesized using lead iodide and nitrogen heterocyclic ligand?PYTPY?as precursors by solvothermal method.physicochemical characterization shows that the iodine lead chain in the structure of compound 5 is a good carrier conductor with a small energy gap value.the results of crystal anisotropy conductivity of the compound 5?along the direction of the iodine-lead chain and perpendicular to the iodine-lead chain?showed that the single crystal conductivity along the iodine lead chain is two orders of magnitude higher than the single crystal conductivity perpendicular to the iodine lead chain.compound 5 is an anisotropic single crystal semiconductor material.