Adsorption And Stimuli-Responsive Behaviors Of Bipyridinium-Based Coordination Polymers

As a new type of organic-inorganic hybrid materials,the metal organic coordination polymer has been widely concerned by the chemists with its diverse structures and excellent physical or chemical properties.Viologen/bipyridinium derivatives as a kind of macromolecule conjugated compounds,with its unique optical activity and redox activity,has shown wide application prospects in areas such as biology,photochemistry,electrochemistry and materials chemistry.In this work,we successfully obtain eight novel coordination polymers,which are synthesized by solvent heat or volatile methods.Their structures and properties have been characterized by X-ray single-crystal/powder diffraction studies,IR,UV-Vis,luminescent spectra,electron spin resonance,elemental analysis,thermogravimetric analysis and organic vapor adsorption analysis.Simultaneously,we discuss the influence of different auxiliary ligands and solvent condition on the final structure and photochromic properties of the compounds,we also explore the adsorption and the photoluminescence properties of some complexes.The innovative features of my present work are described as follows:(1)We have synthesized the flexible HBCbpyCl ligand by the nucleophilic substitution reaction,and selected different metal ions and auxiliary ligands with carboxylic acid groups to assemble with it.(2)Through changing the metal ions and choosing different auxiliary ligands containing phthalic acid,we have obtained four coordination polymers{[Cu(BCbpy)(o-BDC)(H₂O)]?0.5H₂O}n(2-1),{[Cu(BCbpy)(ox)(H₂O)]?H₂O}n(2-2),{[Cu(BCbpy)(ox)]?1.5H₂O?0.5DMF}n(2-3)and{[Cd₂(BCbpy)₂(PMA)]?12H₂O}n(2-4).The steric effect of phthalic acid restricts the further expanding of the structure.The introduction of oxalic acid and phthalic acid is more likely to form porous complexes with one-dimensional polar pore channels,which shows good adsorption effect on the polar small molecules,like methanol,ethanol and water molecules.As the distance between the donor and acceptor is avaliable for the electron transfer,compound 2-2 and 2-3 show excellent optical activity.(3)We choose 5-methylisophthalic acid(H₂mip)and 5-hydroxyisophthalic acid(H₂hip)as the auxiliary ligands to construct four coordination polymers,{[Cd₃(BCbpy)₂(hip)₂(H₂O)₆Cl₂]?8H₂O}n(3-1),{[Zn(BCbpy)(hip)(H₂O)]?4H₂O}n(3-2),{[Cd(BCbpy)(mip)(H₂O)]?2H₂O}n(3-3),{[Zn(BCbpy)(mip)(H₂O)]?2H₂O}n(3-4).For compound 3-1 and 3-2,the introduction of the hydroxyl group supports the existence of a charge-transfer interaction and weaken the photoinduced electron transfer,thus no color development can be observed.Relatively speaking,compounds with methyl group show rapid light discoloration phenomenon and excellent optical activity.