Metal-Organic Frameworks Based On Semi-Rigid Aromatic Carboxylate: Syntheses,Structures And Functions

In the dissertation,twenty-two new metal-organic frameworks（MOFs）have been successfully constructed based on two semi-rigid aromatic carboxylic acids,viz.4,4’-dicarboxy-4’’-nitrotriphenylamine（H₂L）and 4-（carboxymethoxy）-[1,1’-biphenyl]-3,4’-di-carboxylic acid(H₃L_ws),under hydrothermal or solvothermal conditions.Syntheses,structures and properties of these complexes have been investigated and discussed in detail and the main work of this dissertation includes the following four parts:（1）MOFs based on H₂L ligand and Zn²⁺/Cd²⁺ions:[Zn（L）（4,4’-bpy）_0.5].（H₂O）_0.25（1）,[Cd₄（L）₄（4,4’-bpy）].2（H₂O）（2）and[Zn₄（L）₄（4,4’-bpy）（H₂O）₂].2H₂O.2CH₃CN（3）.Complexes1 and 3 are two 2-D layered structures based on 1-D beaded chains,and complex 2 exhibits a two-fold interpenetrating 3-D network.Complexes 1 and 2 can serve as a highly sensitive and selective fluorescence sensor for aqueous detection of hydrogen sulfide,and the detection limit of 1 and 2 was 7.9μM and 0.2μM,respectively.Complex 3 has the ability to detect Fe³⁺ion in DMAc solvent.（2）Three MOFs based on H₂L ligand and Cu²⁺/Co²⁺ions:[Cu（L）（H₂O）].（CH₃CN）_0.25（4）,[Co₄（L）₄（4,4’-bpy）（H₂O）₂].2H₂O（5）and[Co（L）（Phen）（6）.Complex 4exhibits a 3-D porous network assembled by 2-D two-fold interpenetrating sheet comprising helical chains,and shows outstanding chemical robustness which can withstand acidic or basic aqueous solution as well as various organic solvents.Complex 4 displays a typical antiferromagnetic interaction between adjacent copper ions.In particular,complex 4 not only displays a notable visible-light photocatalytic activity for degrading oragnic dyes（e.g.crystal violet（CV）,rhodamine 6G（R6G）,congo red（CR）and basic red 2（BR2））with the assistance of H₂O₂ but also can catalyze the oxidation-coupling reaction of phenylboronic acid and its derivatives.Complex 5 is a 2-D layered structure based on octahedral cage,and complex 6 exhibits a 1-D zigzag chain with good thermal stability.（3）MOFs based on H₂L ligand and lanthanide metal ions:[La（H₂L）（H₂O）].（CH₃CN）_0.25]（7）,[La₂（L）₃（H₂O）₄].（CH₃CN）₃.H₂O（8）,[Nd₂（L）₃（H₂O）₄].H₂O（9）,Tb₂（L）₃（H₂O）₃.（CH₃CN）.（H₂O）_1.5（10）,Eu₂（L）₃（H₂O）₃.（CH₃CN）₂.（H₂O）(11,Sm₂（L）₃（H₂O）₃.（CH₃CN）（12）,Dy₂（L）₃（H₂O）₃.（CH₃CN）.（H₂O）（13）,Yb₂（L）₃.（H₂O）_1.5（14）,[Ce₂（L）₃（H₂O）₄].CH₃CN（15）,[Pr₂（L）₃（H₂O）₄].（CH₃CN）₄（16）and Er₂（L）₃.（CH₃CN）（17）.Complex 7（La）is a 3-D porous MOF constructed by stacking of 2-D layered structures and can be used as a fluorescent probe for detecting Fe³⁺and Cu²⁺ions.Complexes 8（La’）,9（Nd）,15（Ce）and 16（Pr）are isomorphic with the raz2 topology.Amongst,8（La’）and 9（Nd）can serve as probes to detect Fe³⁺ion.Complexes 10（Tb）,11（Eu）,12（Sm）and 13（Dy）are also isostructural dispalying 3-D porous structures based on rod-shaped metal chains and bridging ligands.Among them,complex 10（Tb）has the ability to identify Fe³⁺and Cu²⁺;Complexes11（Eu）and 12（Sm）can act as a fluorescent probe for detecting benzaldehyde in benzyl alcohol solvent.Complexes 13（Dy）and 14（Yb）display different luminescence responses toward different NACs with superb sensitivity for 2,4-DNP,TNP and PNP.The structures of17（Er）and 14（Yb）are similar,wherein all metal ions adopt the pentagonal double-cone geometry to connect with the ligand forming a three-dimensional network containing three kinds of channels.（4）MOFs based on H₃L_wss and H₂bsal ligands:Co(HL_ws)].（H₂O）₂（18）,Ni₂(L_ws)（OH）（H₂O）₃（19）,Cd₂(L_ws)（OH）（20）,Cu（Hbsal）₂（4,4’-bpy）₂（21）and Cu（Hbsal）（4,4’-bpy）（22）.Complexes 18 and 19 are 1-D chain and 2-D layered structures,respectively,and there are a large number of hydrogen bonds in their structures,which greatly improves their hydrolytic stability.Complex 20 is a 3-D non-interpenetrating network,and shows superb sensitivity for NACs especially for 2,4-DNP,TNP and PNP.Complexes 21 is a1-D linear chain,and 22 is a 3-D porous supermolecular framework with sod topology.What is the most interesting finding is that compound 21 can be irreversibly transformed into 22 in a crystal-to-crystal manner in the case that compound 21 is immersed into DMF solvent.Particularly,the 1D-to-3D crystal-to-crystal structural transformaiton also incurres a drastic change in the magnetic properties of 21 and 22.