| Organic photochromic molecules,which could change their colors under illumination,have been widely used in development of advanced multifunctional materials due to their reversible photoinduced changes of structures or electronic states.Viologens/4,4'-bipyridiniums possess extensively potential applications in biology,electrochemistry,photochemistry and material chemistry fields due to their?-conjugate blocks,excellent redox-active nature,photochromism and conductivity.With the metal ion as the node and the photoelectric active organic molecule as the linker,the molecular to material conversion can be realized by functional organic molecules and their coordination complexes in ordered arrangements through weak intermolecular interactions or coordination,which has provided an important and efficient way for the preparation of novel functional materials.Our project is to utilize photochemical pyridinium ligands as functional building block and introduce different types of auxiliary ligands.Through supramolecular or coordination assemblies,we successfully obtained 11bipyridinium-based coordination polymers,which are characterized by IR,UV,EA,TGA,EPR,X-ray single-crystal/powder diffraction studies.Simultaneously,we discuss the effect of different molecular configurations on the photochromic properties of the complexes and explore the ammonia response of some complexes.The innovative features of my present work are described as follows:?1?We chose the flexible H2BpybcCl2 ligand to form novel compounds with different metal ions and auxiliary ligands under mild experimental conditions,in which we can adjust the auxiliary ligands to control its optical activity.Not only the cost of synthesis of the complex is low,but also it is not harmful to the environment and human.?2?Through changing the metal ions and choosing the same hydroxybenzoic acid,we obtained two isomeric polyrotaxane structure{[Zn?Bpybc?1.5?1,4-HBA?H2O].6H2O}n?2-1?and{Cd?Bpybc?1.5?1,4-HBA?.8.5H2O}n?2-2?.We found that the self-assembly of hydroxybenzoic acid with H2BpybcCl2 and different metal ions has the tendency to form a specific polyrotaxane structure.As the distance between the donor and acceptor of the electron is too far and the electron transfer can not occur,so the two compounds possess no photochromic properties.?3?Through supramolecular self-assembly with different auxiliary ligands and metal ions,we obtained four one-dimensional“Z”chain structures{[Cu?Bpybc??1,2-HBA??H2O?1.5].?H2O?3}n?3-1?,{[Cd0.5?Bpybc?0.5?1,2-HBA?0.5].?H2O?2}n?3-2?,{[Co?Bpybc??N3?2].3H2O}n?3-3?and{Cd?Bpybc?Cl2.2H2O}n?3-4?.Due to the different electron-donating abilities of the auxiliary ligands,we found that 3-13-3exhibited optical activities that is different from of 3-4.Therefore,3-13-3 are optically inactive and 3-4 shows good photoactivity.?4?Through coordination assemblies with the same metal cadmium ion and different carboxylic acid auxiliary ligands with stronger electron donating ability,five compounds with better photoactivity were constructed{[Cd?Bpybc??ox?].H2O}n?4-1?,{[Cd4.5?Bpybc?1.5?TBC?3].8H2O}n?4-2?,{[Cd1.5?Bpybc?0.5?TBC?H2O].H2O}n?4-3?,{[Cd?Bpybc?0.5?DBC?H2O].H2O}n?4-4?,{[Cd2?Bpybc??DBC?2H2O].2H2O}n?4-5?.Since zthe strong electron-donating abilities of the electron-rich carboxylate with the appropriate distance and angle between the donor and acceptor,which result in the process of electron transfer.Thus,the compounds have excellent photochromic properties. |
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