Metal Organic Frameworks Based On A Flexible Tripodal Ligand Synthesis, Structures And Properties

The design and synthesis of coordination complexes are great attractive not only for their potential applications in photochemical areas, magnetism, sorption, exchange and catalysis but also for their intriguing variety of architectures and captivating topologies. The properties of the complexes are closely related to their structures. The rational selection of metal centers and organic ligands with suitable shape plays a crucial role in synthesizing complexes with versatile structures and desired properties. Hence, we chose a flexible tripodal ligand (tttmb) to act as main ligand, and introduced five polycarboxylates with different geometric shape as auxiliary ligands into the Cd(II)/Co(II)-tttmb synthesis system. Seven novel complexes were synthesized under the hydrothermal/solvothermal conditions. The structural and topological analyses of these complexes, as well as the effects of tttmb and carboxylates on the structures have been discussed in detail. Furthermore, their elemental analysis, infrared analysis, thermal stabilities, and photoluminescence were studied.1, By using1,3,5-tris(triazol-1-yl-methyl)-2,4,6-trimethylbenzene (tttmb) and five organic carboxylate coligands, we synthesized seven complexes hydrothermal/solvothermal conditions:{[Cd5(tttmb)2(tbi)5(H2O)4].2H2O}n (1),{[Cd(tttmb)(atc)]-1.5H2O}n (2),{[Cd2(tttmb)2(btc)Cl]-1.5H2O}n (3),{[Cd3(tttmb)2Cl6(H2O)6]4H2O}n (4),[Co2(tttmb)(m-bdc)2H2O]n (5){[Co(tttmb)(dpe)]-2H2O}n (6),{[Co1.5(tttmb)(btc)(H2O)]-3H2O}n (7)(H2tbi=5-tert-Butylisophthalic Acid, H2atc=1,3-Adamantanedicarboxylic Acid, Hsbtc=1,2,4-Benzenetricarboxylic Acid, m-H2bdc=1,3-Benzenedicarboxylic Acid, H2dpe=4,4’-Dicarboxydiphenyl Ether). Single crystal X-ray analysis reveals complexes1,2,4,5show2D network. Complex1displays an intricate two-dimensional framework containing three layers and tbi2" takes on five different coordination modes in1.2and5exhibit different two-dimensional structures with left-and right-handed helical chains arranged alternately. The structure of complex4is a2D honey comb structure. Complexes3,6,7show3D structure. Complex3displays a self-penetrating3D pillar-layered3,4,8-connected framework with (4-62)(66)(42-620-86) topology. Complex6exhibits a2-fold interpenetrated3D networks with (4·5·65·72·8)(4·5·6) topology. Complex7shows a3D (52·7)(52·73·8)(44·54·62·74·10) topology.3,6,7contain left-and right-handed helical chains. The effects of carboxylates and tttmb on the structures have been discussed in detail. The results reveal that tttmb is a good candidate for the syntheses of intriguing complexes with diverse structures and specific topologies.2, the solid state photoluminescence properties of complexes1-3, together with the free tttmb and carboxylic acids H2tbi and H3btc were investigated at room temperature. Complexes1-3with the same metal centers and N-donor ligand show different photoluminescence behaviors, which is probably attributed to the differences in the features of polycarboxylate coligands and the structures of complexes. Moreover, the thermal stabilities of1,2,5,6, and7were studied. Complex5shows super thermal stability in the DMF, CH3OH, C2H5OH, CH3CN, and CHCI3. Furthermore, we investigated the adsorption properties of I3-anion.