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Two isomeric zeolite-like metal–organic frameworks with the formula of [(CH3)2NH2][Cd(TPO)]·xsolvent were successfully prepared and characterized. Both frameworks are constructed from tetrahedral TPO3− nodes and tetrahedrally connected Cd2+ nodes, representing rare examples of zeolite-like MOFs with an isomeric characteristic. Moreover, one of the frameworks shows mechanically responsive luminescence emission after the crystals are ground for different times. Additionally, it has permanent porosity, and can selectively adsorb CO2 over N2.

Two novel inorganic–organic hybrid 3D TM–Ln incorporated POM-based frameworks, H2[Cu2OL3(H2O)2][Ce(L)(H2O)3(PW11O39)]·17H2O (1) and H4[CuL3]2[Ln(H2O)3(PW11O39)]2·28H2O (2) (L = 4,4′-bipyridine), were hydrothermally synthesized at different temperatures. Structural analysis reveals that both compounds are constructed from [Ln(PW11O39)]4− polyoxoanions and different copper complexes. Interestingly, in compound 1, 2D copper complex layers and 1D chain [Ln(PW11O39)]4− polyoxoanions interconnect to form a 3D framework. In contrast, in compound 2, 1D copper complex chains join the 2D [Ln(PW11O39)]4− layers to give rise to a 3D framework. Both compounds exhibit excellent chemical stability. Furthermore, the dye adsorption and proton conduction properties of both compounds were also investigated. The conductivities of 1 and 2 are 3.175 × 10−4 S cm−1 and 1.750 × 10−4 S cm−1 at 85 °C and 98% RH, respectively. Dye adsorption studies indicate that they can selectively adsorb cationic dyes MB, CV and BR over anionic dyes MO, AO and large cationic RhB.

A series of heterometallic cluster organic frameworks based on cuprous-halide Cu4I4 clusters and lanthanide clusters, [Ln2(H2O)8]2(Cu4I4)(pdc)4][NO3]4·solvent (1-Ln, Ln = Y, Tb, Eu, H2pdc = 3,5-pyridinedicarboxylic acid), have been successfully synthesized under solvothermal conditions. Single-crystal X-ray diffraction analysis reveals that 1-Ln show fascinating three-dimensional porous framework structures constructed from two dissimilar types of nanosized coordination cages. Gas sorption measurements indicate that 1-Ln show moderate gas uptake capacities. The UV/vis spectroscopy measurements reveal that 1-Ln are a class of potential materials for the removal of Cr2O72− from aqueous solution. Additionally, the luminescence properties of 1-Tb and 1-Eu have also been investigated.

The first transition-metal-bridged polyniobotungstate-based 3D framework has been hydrothermally synthesized, which is constructed from bi-[CuII(en)2(H2O)]-decorating [Nb3W3O19]5− polyoxoanions linked together by CuI ions. Interestingly, the 3D polyniobotungstate framework can undergo a solid–liquid reaction with KI solution to generate a 1D copper halide of [Cu(en)2][CuI2]2 in a single-crystal-to-single-crystal process.

In order to systematically investigate the effects of 5-positioned substituents in isophthalates on the structures and properties of coordination polymers, six Cu(II) coordination polymers, [Cu2(bmib)(HO–ip)2]n (1), [Cu4(bmib)(OH)2(MeO–ip)3]n (2), [Cu(bmib)(MeO–ip)]n·(DMF)2n·(H2O)2n (3), [Cu(bmib)0.5(H2O)(EtO–ip)]n·(DMF)0.5n (4), [Cu(bmib)(PrO–ip)]n·(H2O)2.5n (5) and [Cu(bmib)(BnO–ip)]n·(DMF)n (6) have been synthesized by hydrothermal reaction of 5-hydroxyisophthalate derivatives (RO–ip, R = H, Me, Et, Pr and Bn), 1,4-bis(2-methylimidazol-1-yl)benzene (bmib) and Cu(NO3)2·3H2O. Their structures have been confirmed by single crystal X-ray diffraction analyses, IR spectroscopy, TGA and elementary analyses. In 1, μ3-bridged HO–ip links dinuclear Cu(II)–carboxylate units into a 2-D layer, which is further pillared by bmib to generate a two-fold interpenetrating 3-D network. However, μ4-bridged MeO–ip in 2 connects Cu(II) into a 3-D coordination network consisting of tetranuclear Cu(II)–carboxylate units, bmib serves as a void filler by bridging between tetranuclear units. In 3, bis-chelating MeO–ip and bmib link Cu(II) into a 2-D layer, which is packed in an eclipsed pattern. In 4–6, Cu(II) ions are in a distorted square-planar geometry, and carboxylate ligands adopt a bis-monodentate bridging mode and connect the Cu(II) ions into a charge-neutral chain. A pair of such chains in 4 is pillared by bmib to form a pillared-bichain structure, while bmib in 5 and 6 bridges the adjacent chains, resulting in the formation of different 2-D layers. The packing of the 2-D layers in 5 and 6 generates 1-D channels containing guest molecules, which are confirmed by their TGA analyses. The temperature-dependent magnetic analyses show that the dinuclear and tetranuclear Cu(II) units make up the basic magnetic unit of 1 and 2, respectively, and they show an antiferromagnetic interaction.

Two unprecedented heterometallic metal–organic frameworks (MOFs), Ag2(btr)2Cr2O7·0.5H2O (1) and Ag9(btr)6(Cr2O7)4·PF6·6H2O (2) [btr = 4,4′-bis(1,2,4-triazole)], were synthesized through crystal-to-crystal transformation when the monometallic MOF Ag2(btr)2·2ClO4·3H2O was immersed in the aqueous solutions of KPF6–K2Cr2O7 and NaBF4–K2Cr2O7, respectively. The transformation follows a solvent-mediated anion-induced mechanism through the dissolution–reaction–crystallization process. Single-crystal X-ray diffraction analyses reveal that both 1 and 2 are three-dimensional structures based on Ag+, Cr2O72− and btr. In 1, Cr2O72− adopts a bidentate bridging mode, and Ag+ ions are linked by Cr2O72− and btr into a neutral framework. However, Cr2O72− in 2 exhibits two types of unprecedented bridging modes through bridging four and five Ag+ ions. Ag+ ions in 2 are bridged by Cr2O72− and btr to form a cationic framework. The non-coordinated BF4−/PF6− anions show a structure-directing effect during the crystal-to-crystal transformations and can be considered as structure-directing agents. The second-harmonic-generation (SHG) measurement shows that 1 is a non-linear optical complex.