Two new metal–organic frameworks (MOFs) based on TMBDI linker (TMBDI = 2,3,5,6-tetramethyl-1,4-diisophthalate) and [M2(COO)4] paddlewheel, {[Zn2(TMBDI)(H2O)2]•2.5DMF•2(1,4-dioxane)•6H2O}n (UPC-6) and {[Co2(TMBDI) (DMA)2]•2DMA•5EtOH}n (UPC-8), have been obtained under solvothermal conditions. Due to the low stability of Zn/Co paddlewheels upon the removal of axial solvates, UPC-6 and UPC-8 possesses a very low surface area and adsorption capacity. Through metal-ion metathesis in a single-crystal-to-single-crystal fashion, two new Cu(II) MOFs (termed Cu-UPC-6 and Cu-UPC-8) with identical robust frameworks were produced, which could not be prepared by routine solvothermal methods. Meanwhile, the influence of the reaction solvents on the metathesis process were also investigated, and the results show that the form of solvented ions can induce obviously kinetic issues. Through gas adsorption measurements, the stability and porosity of frameworks have been shown improved significantly.

Two amino-functional copper metal–organic frameworks of formula [Cu3(ATTCA)2(H2O)3]·2DMF·11H2O·12EtOH (1) (H3ATTCA = 2-amino-[1,1:3,1-terphenyl]-4,4,5-tricarboxylic acid, pyz = pyrazine, DMF = dimethylformamide) and [Cu3(ATTCA)2(pyz)(H2O)]·2DMF·12H2O·8EtOH (2) were synthesized under solvothermal conditions and characterized by single-crystal X-ray diffraction, infrared spectroscopy, elemental analyses, thermogravimetric analyses, and powder X-ray diffraction. Single-crystal X-ray diffraction analysis revealed that both complexes 1 and 2 are built of the Cu2(COO)4 paddlewheel secondary building units with an fmj topology. Importantly, complex 1 can be transformed into complex 2 by the single-crystal to single-crystal transformation of which the coordinated water molecules are replaced with pyz molecules. However, the adsorption abilities of 2 are obviously lower than those of 1, as its pores are partially blocked by pyz molecules. Moreover, gas-adsorption analysis showed that the amino-functional 1 possesses higher gas-adsorption capacity than UMCM-151 for N2, H2, CH4, and C2H2, especially for CO2.

Three new mixed-ligand coordination networks, [Cd2(ADDA)(bipy)(H2O)2]·2H2O (1), [Zn(ADDA)(bipy)0.5]·NMP·2H2O (2), and [Co(ADDA)(bip)(H2O)2]·H2O (3) (bipy = 4,4′-bipyridine, bip = 1,4-di(1H-imidazol-1-yl)benzene, H2ADDA = 3,3′-(anthracene-9,10-diyl)diacrylic acid), have been synthesized based on 3,3′-(anthracene-9,10-diyl)diacrylate acid and different N-donor ligands under solvothermal conditions, and structurally characterized by single-crystal X-ray diffraction analyses, infrared spectroscopy (IR), elemental analyses, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Topological analysis reveals that 1 features a rare 8-connected 3D ilc network with the point symbol of {4∧24.5.6∧3}; complex 2 possesses a 3D open framework based on the infinite Zn–(CO2) chain with the point symbol of {6∧2.8∧4}; while complex 3 shows a normal 2D 3-connected coordination network with hcb topology and the point symbol of {6∧3}. Besides, the luminescence properties of complexes 1 and 2 were also investigated. The results show that complex 2 bears rapid and selective sensing of Fe3+ in methanol suspension at room temperature.

A pair of framework-catenation isomers (UPC-19 and UPC-20) based on an anthracene-functionality dicarboxylate ligand were synthesized and characterized for the first time through tuning of the dimensionality of interpenetration. The interpenetration dimensionality significantly influences the properties including the porosity, gas-uptake capacity, and fluorescent sensing ability: UPC-19 with 5-fold interpenetration is nonporous, whereas the 3-fold interpenetration form of UPC-20 is porous and exhibits selective adsorption of CO2 and fluorescent sensing of Cu2+ and Fe3+ through fluorescence quenching.

Three new mixed-ligand metal–organic coordination networks based on naphthalene-2,6-dicarboxylic acid and different bis(imidazole)s, [Cd(bmimb)0.5(ndc)]·1.5H2O (1), [Zn(bibp)(ndc)]·H2O (2), [Zn(bip)(ndc)]·2H2O (3), (bmimb = 1,4-bis((2-methyl-1H-imidazol-1-yl)methyl)benzene, bibp = 1,1′-(2,5-dimethyl-1,4-phenylene)bis(1H-imidazole), bip = 1,4-di(1H-imidazol-1-yl)benzene, H2ndc = naphthalene-2,6-dicarboxylic acid), have been synthesized under solvothermal conditions and structurally characterized by single-crystal X-ray diffraction analyses, infrared spectroscopy (IR), elemental analyses, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). These complexes display different types of entanglements. Topological analysis reveals that 1 features a 3-fold interpenetrated pcu network constructed from paddle-wheel secondary building units. Complex 2 exhibits a normal mode of a 5-fold diamondoid interpenetrating net, while complex 3 is a 3D 4-connected coordination network with an extremely rare (65·8)-hxg-d-4-Cccm topology. These results suggest that both naphthalene-2,6-dicarboxylic acid and bis(imidazole) ancillary ligands influence the final resulting structures. Furthermore, luminescence properties and thermogravimetric properties of these complexes were investigated.

Two 2-fold interpenetrating metal–organic frameworks based on 1,3,5-tris[2-(4-carboxyphenyl)-1-ethynyl]-2,4,6-trimethylbenzene (H3LMe), [Mn3(LMe)2(DMF)4(H2O)]·1.5DMF·3.5H2O (1) and [Cd3(LMe)2(DMF)][Cd3(LMe)2(DMF)2(H2O)]·5DMF·3.5H2O (2), have been synthesized by using rigid trigonal H3LMe and nitrate under solvothermal conditions. Complex 1 displays a three-dimensional open framework with rare (3,6)-connected 2-nodal sit topology, whereas complex 2 features a new (3,3,6)-connected topology. Both 1 and 2 are blue fluorescent, and the magnetic measurement of 1 indicates that metal centers within the trinuclear cluster exhibit antiferromagnetic coupling interactions. Significantly, although complexes 1 and 2 have similar total solvent-accessible volumes, 2 demonstrates a higher Brunauer–Emmett–Teller surface area than that of 1, further indicating the influence of pore structure on gas absorption.