Synthesis And Properties Of Metal-Organic Coordination Polymers Based On N/O Containing Multifunctional Ligands

The design and synthesis of metal-organic coordination polymers based on the crystal engineering has become one of the most popular studies in the fields of coordination chemistry and material chemistry. Due to their tunable structures and functionalities, coordination polymers have potential applications in many areas, including optics, electricity, catalysis, magnetism, sensing, gas storage and separation and so on. We have synthesized nine new metal-organic coordination polymers by hydrothermal methods and studied their applications in three aspects: the crystal engineering towards the tuning luminescence property of coordination polymers by designing the structures; coordination polymers used as fluorescence sensors for highly selective and sensitive detection of nitrobenzene; preparation of nanocomposites with high photocatalytic activity by one-step thermolysis of coordination polymers.1. Under hydrothermal conditions, by using N containing multifunctional ligands 5-(methylthio/ethylthio)-1H-tetrazole and Cu metal centers as additives and using HCl solution as p H modifier, four new coordination polymers have been obtained:[Cu(mttz)](1)[Cu2(mttz)Cl](2)[Cu(ettz)](3)[Cu2(ettz)Cl](4)Compounds 1 and 3, compounds 2 and 4 are isostructures. Compounds 1 and 3 show two-dimensional layered structures. Compounds 2 and 4 show three-dimensional frameworks. Luminescence investigation displays that the emission spectra of compounds 1 and 3 display a main peak and a shoulder peak, whereas the emission spectra of compounds 2 and 4 display one emission band. Compounds 2 and 4 show strong rigidity. For compounds 2 and 4, the long distance between adjacent ligands influences the hydrogen bonding, leading to tuning luminescence property.2. Under hydrothermal conditions, by using O containing multifunctional ligand 2,4-dichloro-5-sulfamoylbenzoic acid(H3sba) and flexible ligand 1,3-bis(4-pyridyl)propane(bpp) as well as transition and main group metal centers as additives, using hydroxide solution and aqueous ammonia as p H modifiers, three new coordination polymers have been obtained:[Pb(bpp)3(H2sba)2](5)[Cd(bpp)(Hsba)·H2O](6)[Ag2(bpp)(Hsba)]·H2O(7)Compound 5 displays a one-dimensional wavelike chain. Compound 6 shows a 2-fold parallel interpenetration bilayers. Compound 7 exhibits a multi-sandwiching supramolecular structure, in which left- and right-handed helical chains are anchored by the adjacent layers. Compounds 5-7 are luminescent materials and used as fluorescence sensors for highly selective and sensitive detection of nitrobenzene. They have excellent antiinterference abilities and good stabilities.3. Under hydrothermal conditions, by using multifunctional ligand 2,4-dichloro-5-sulfamoylbenzoic acid(H3sba) and flexible ligand 1,3-bis(4-pyridyl)propane(bpp) as well as Zn metal centers as additives, two new coordination polymers have been obtained:[Zn(bpp)(Hsba)](L)(8)[Zn(bpp)(Hsba)](D)(9)Compounds 8 and 9 are enantiomers. The structures of compounds 8 and 9 are formed by alternating assembly of two types of homochiral helical chains. The Zn-Hsba helical chain is single-stranded, in which Hsba2- connects two Zn atoms via one sulphonylamino N and one carboxylate O atoms. The Zn-bpp helical chain is double-stranded, which is constructed by bpp bridged between Zn atoms. These two types of homochiral helical chains are in an alternate arrangement by sharing of Zn atoms to build a two-dimensional(2D) chiral helical layer. Zn S@N-C core-shell nanocomposite has been synthesized by one-step thermolysis of compounds 8 and 9, in which Zn S particle is encapsulated into the N doped carbon layer. Zn S@N-C nanocomposite exhibits excellent catalytic ability for the selective oxidation of cis-cyclooctene under visible light irradiation.