Synthesis And Properties Of Transition Metal-Organic Coordination Complexes

Metal-Organic Frameworks(MOFs) have attracted much attention because of their unique structures and potential applications in the area of gas sorption, separation, catalyst, fluorescence, electronics and magnetism.In this paper, we have chosen different flexible dicarboxylate ligands and rigid N-donor ligands and constructed 19 transition metal-organic coordination polymers: Zn(dpd)(4,4’-bpy)0.5(1), Zn(Hdpd)2(4,4’-bpy)2·H2O(2), Co3(Hdpd)2(dpd)2(4,4’-bpy)3(H2O)2·2H2O(3), Co(Hdpd)2(4,4’-bpy)(H2O)2·2H2O(4), Ni(Hdpd)2(4,4’-bpy)(H2O)2·2H2O(5), Mn(dpd)(bpy)(H2O)(6), Co(dpd)(bpy)(7), Cu(dpd)(H2dpd)(bpy)(8), Mn(dpd)(phen)2(H2O)(9), Co(dpd)(phen)(H2O)(10), Co(dpd)(phen)(H2O)(11), Mn(cob)(phen)(12), Co(cob)(phen)2(H2O)·5H2O(13), Co(cob)(phen)(14), Cd(cob)(phen)(15), Mn(cob)(2,2’-bpy)(H2O)2(16), Co(cob)(2,2’-bpy)(H2O)2(17), Cu(Hcob)2(2,2’-bpy)(H2O)2·H2O(18), Cd(cob)(2,2’-bpy)(19),(H2dpd = 2,4-diphenyl ether dicarboxylic acid, 4,4’-bpy = 4,4’-bipyridine, 2,2’-bpy = 2,2’-bipyridine, phen = 1,10-phenanthroline, H2 cob = 2-[(4’-carboxybenzyl)oxy]benzoic acid), corresponding characterization and properties have been studied. Complexes 1-5 are synthesized under hydrothermal conditions by 2,4-diphenyl ether dicarboxylic acid and bridging N-donor ligand with different transition metal salts. Complex 1 displays a 3D framework with {4·82}{4·82·103} topology. Complex 2 is a mononuclear structure which is further self-assembled through both hydrogen bonding and π···π stacking interactions to generate a 3D supramolecular structure. Complex 3 shows a 2D ladder network with {4·62}2{42·62·82} topology, which consists of 1D ladder-like chains. Complexes 4 and 5 are isostructural and feature 1D chains which are further connected by hydrogen bonding interactions to form 2D supramolecular structures. Complexes 6-11 are synthesized by 2,4-diphenyl ether dicarboxylic acid and chelating N-donor ligands with different transition metal salts. Complex 6 is a 3D(3, 3)-connected framework which is connected by dpd2– ligand. Complex 7 shows 1D zigzag chain, which is further connected by hydrogen bonds to form a 3D supramolecular net. Complex 8 is constructed from infinite 1D chains which are linked by dpd2– ligand extending a 2D supramolecular layer. Complex 9 is a mononuclear structure which is further self-assembled through hydrogen bonding and π···π stacking interactions to generate a 3D supramolecular structure. Complexes 10 and 11 are 1D chains and further connected by hydrogen bonding and π···π stacking interactions to form a 3D supramolecular structure. Complexes 12-19 are constructed by 2-[(4’-carboxybenzyl)oxy]benzoic acid and different N-donor ligands with transition metals. Complexes 12, 14 and 15 are isostructural and feature a 2D wave-like layer network, which further interconnected by inter-layer π···π stacking interaction to form a 3D supramolecular structure. Complex 13 and 18 are both mononulear strucures which further self-assembled through hydrogen bonding and π···π stacking interaction to generate 3D supramolecular structures. Complexes 16 and 17 are isostrucural and show 1D zigzag chain, which further connected by hydrogen bonding to form a 2D supramolecular structure. Complex 19 is an infinite 1D linear structure. All these complexes have been characterized by elemental analysis, infrared(IR), thermal gravimetric analysis(TGA), poeder X-ray diffraction(PXRD) and single crystal X-ray diffraction. Furthermore, fluorescence, magnetic and water vapor sorption properties of these complexes have been investigated. Since the deprotanation degree of the flexible dicarboxylate ligands can provide different coordination geometry to link metal centers, various structures can be obtained. Different rigid bridging and chelating secondary ligand can also affect the coordination of metal centers. Moreover, the functional groups in these ligands can provide hydrogen bonding and π···π stacking interactions for the construction of three dimensional supromolecular structures. Based on the analysis for the different dimensions of these complexes, we can get more experience for further rational synthesis of metal-organic frameworks.Also, we chose a transition metal-nickel coordination complex to catalyze the arylation of diarylmethanes with both aryl bromides and aryl chlorides. The success of this reaction relies on the introduction of a unique nickel(NIXANTPHOS)-based catalyst system, which provides a direct route to triarylmethanes from heteroaryl-containing diarylmethanes, without the prefunctionalization of organometallic reagents. Reactivity studies indicate the Ni(NIXANTPHOS)-based catalyst exhibits enhanced reactivity over XANTPHOS derivatives. To test the generality of the Ni(NIXANTPHOS)-based catalyst, a novel arylation of a 2-pyridylmethyl amine was examined. Out of the 37 mono- and bidentate cross-coupling ligands examined with Ni(COD)2, NIXANTPHOS again showed the highest reactivity. These results are the first hint that the exceptional reactivity of NIXANTPHOS-based nickel catalysts may be translatable to different arylation system.