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Coordination polymers have received immense attention for proton conduction owing to their highly tunable and designable structures. Herein, based on the flexible ligand 5-(4-pyridine)-methoxyisophthalic acid (H2L), two novel highly chemically stable indium coordination polymers (In-CPs), InL(H2O)Cl·H2O (In–L–Cl) and InL(H2O)(NO3) (In–L–NO3), were synthesized through solvothermal methods. In–L–Cl and In–L–NO3 are isostructural, in which every individual In(III) atom connects to L2− to form a single layer, and coordinated Cl− and NO3− are inserted into the windows of the interlayers. Both of them possess high water and chemical stability. More importantly, the abundant Cl− and NO3− exposed in the interlayer can act as hydrogen bond acceptors to facilitate the formation of a dense hydrogen bonding network, thus improving proton transfer efficiently. Electrochemical impedance spectroscopy shows that In–L–Cl and In–L–NO3 display optimized proton conductivities of 1.88 × 10−3 and 1.00 × 10−3 S cm−1 at 100% relative humidity (RH) and 80 °C, respectively. The difference in proton conductivity of In–L–Cl and In–L–NO3 likely stems from the variations in the hydrogen bonding networks formed by lattice water and the different electronegativities of the coordinated anionic functional sites. This study provides an alternative way to prepare highly proton-conductive CPs.

By introducing the 1,2,4-triazole ligand in the tetracarboxylate system, an anionic metal–organic framework [(CH3)2NH2][Zn2(ABTC)(Tz)]·3DMF (compound 1, ABTC = 2,2′,5,5′-azobenzene tetracarboxylic acid, Tz = 1,2,4-triazole and DMF = N,N-dimethylformamide) was synthesized under solvothermal conditions. There were two types of inorganic secondary building units (SBUs) in compound 1, i.e., a classical Zn-paddlewheel [Zn2(COO)4] and a metal cluster of [Zn2(Tz)2(COO)4], which were linked by ABTC4− to form a 3D porous framework. Because of the two inorganic SBUs as 6-connected nodes and ABTC4− as 4-connected nodes, compound 1 could be simplified to with a point symbol of (32·62·72) (34·42·64·75). Compound 1 displayed CO2 adsorption capacity of 92.1 cm3 g−1 at 273 K under 1 atm. Furthermore, 1 exhibited good adsorption capacity for small molecular gases (CH4, C2H6 and C3H8) and excellent separation selectivity for CO2/CH4, C2H6/CH4 and C3H8/CH4.

A novel water stable porous metal–organic framework (MOF), [Cu3(OH)2(IBA)2(CH3COO)2]·DMA (1) (HIBA = 4-(imidazol-1-yl)-benzoic acid, DMA = N,N-dimethylacetamide), has been solvothermally synthesized and structurally characterized. The framework of compound 1 is constructed from rod SBUs with a new (5,8)-connected topology. Compound 1 exhibits exceptional chemical stability under various conditions (organic solvents, water, boiling water or pH = 1–8 acidic and basic aqueous solutions). Meanwhile, it exhibits good selectivity for CO2 over CH4 (6.6 for CO2/CH4 = 0.5/0.5 and 5.8 for CO2/CH4 = 0.05/0.95 under 1 bar at 298 K). The excellent stability of compound 1 is of extreme importance for its practical industrial applications.

Four novel 3d–4f heterometallic–organic frameworks (HMOFs), namely [Gd2(Cu2I2)(C6H4NO2)6(C3H7NO)(H2O)]·(C3H7NO) (1), [Gd2(Cu4I4)(C6H4NO2)6(C3H7NO)2] (2), [Gd2(Cu6I6)(C12H8NO2)6(C2H6O)2(H2O)2] (3) and [Gd2(Cu8I8)(C12H8NO2)6(H2O)4]·5(C4H8O2) (4), have been solvothermally synthesized and characterized. The four compounds incorporate Cu2I2, Cu4I4, Cu6I6 and Cu8I8 clusters in three-dimensional frameworks, respectively, and the influence of Ln3+ ions, copper halide clusters and ligands on the construction of the structures has been analyzed. The four compounds display four different emission colours. Interestingly, compound 3 responds to external mechanical force. After grinding, the fluorescence has been obviously quenched. Compound 4 displays a reversible luminescence behavior, accompanying the removal and recovery of the guest molecules in the channel.

Three metal–organic frameworks, [Mn(bpydc)]·DMA (JLU-Liu11), [Co(bpydc)DMSO]·(DMSO)(H2O) (JLU-Liu12) and [Co(bpydc)H2O]·H2O (JLU-Liu13), were solvothermally synthesized by reacting a T-shaped linker, 2,2′-bipyridyl-5,5′-dicarboxylic acid (H2bpydc) ligand with transition metals. These compounds exhibit three different types of structures. In JLU-Liu11, two oxygen atoms and two nitrogen atoms of the H2bpydc ligand coordinate to five manganese centers to form an ant net, and JLU-Liu11 displays two types of helical chains with opposite helical directions, which are composed of vertex-sharing 4-rings propagating along the [100] direction. In JLU-Liu12, H2bpydc ligands coordinate to cobalt centers to form a new (3,3)-connected net with two different tiles (6·124) and (62·126). In JLU-Liu13, H2bpydc ligands coordinate to cobalt centers to form a two-dimensional layer which then interacts with terminal water molecules via hydrogen bonds to construct a three-dimensional supramolecular structure, JLU-Liu13 shows exceptional stability in water. Additionally, the magnetic properties of all the compounds were studied.

Reactions of divalent transition metal ions with the N,N′-sulfuryldiimidazole ligand (sdi) gave rise to eleven coordination polymers, namely, [Zn(sdi)(NO3)2(H2O)] (1), [Zn(sdi)2(NO3)2] (2), [Co(sdi)2(NO3)2] (3), [Cu(sdi)2(NO3)2]·2CO(CH3)2 (4), [Mn(sdi)2(H2O)2]·2NO3 (5), [Co(sdi)2(H2O)2]·2ClO4 (6), [Zn(sdi)(bdc)0.5(OCH3)(H2O)]·ClO4·H2O (7), [Cd(sdi)(N3)2] (8), [Mn(sdi)(N3)2] (9), [Ni(sdi)2(SO4)] (10) and [Cd(sdi)0.5(Hbtc)(OCH3)] (11) (H2bdc = 1,4-benzenedicarboxylic acid, H3btc = 1,3,5-benzenetricarboxylic acid). X-ray single-crystal analyses reveal that they have rich structural chemistry ranging from zero-dimensional (0D) (1), one-dimensional (1D) (2–7), two-dimensional (2D) (8) to three-dimensional (3D) (9–11) networks. Compound 1 displays a 0D structure which consists of [Zn(sdi)]2 dimers. Compounds 2–7 possess 1D chains with closed loops. Compound 8 shows a 2D (63) network. Compounds 9 and 10 exhibit 3D uninodal 6-connected pcu frameworks with (412·63) topology. Compound 11 displays a 3D uninodal 4-connected framework with a CdSO4-like net (65·8). The effects of metal ions and anions on the final motifs of the compounds have been discussed in detail. All the compounds are characterized using powder X-ray diffraction (PXRD), IR spectroscopy, thermal stability analysis and elemental analyses. Moreover, the photoluminescence properties of 1, 2, 7, 8 and 11 have been investigated. Magnetic investigation of 9 reveals spin canting antiferromagnetic interactions.

Six new metal–organic frameworks (MOFs), Co2O(odip)(py)2(DMSO)2·3H2O (1), Co2(odip)(H2O)(DMA)2·2DMA (2), Co4(odip)2(H2O)4(DMSO)2·5DMSO (3), [Zn2(odip)(DMF)2(H2O)]·2DMF·2H2O (4), Zn2(odip)(H2O) (5) and In(odip)·3ACN (6), have been synthesized from the 5,5′-oxydiisophthalic acid (H4odip) ligand under solvothermal conditions. These six compounds were characterized by single-crystal X-ray diffraction, power X-ray diffraction and relative physical methods. MOFs 1, 2 and 3 are constructed from the same ligand and metal-salt under the same temperature, but with different solvents, and they exhibit three different topologies. MOF 1 possesses a 3D 4-coordinated architecture with a (65·8) topology. MOF 2 features a 3D 4-coordinated net with a (42·63·8) topology and MOF 3 shows a 3D 4-coordinated framework with a (4·64·8)(4·65) topology. MOFs 4 and 6 have the same topology as MOF 2. MOF 5 exhibits a 3D 5-coordinated framework with a (44·66) topology. These results indicate that the solvent environment plays an important role in the formation of the final framework. Moreover, the photoluminescence properties of 4 and 5, and the magnetic properties of 1, 2 and 3 have been studied and discussed.

Twelve novel three-dimensional (3D) lanthanide metal–organic frameworks with formula {[LnK(C4N2O4S)2(H2O)2](H2O)0.5} (Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8)), {[Ln2K2(C4N2O4S)2(C4O4H2)2(H2O)4](H2O)} (Ln = La (9), Ce (10)), and {[Ln2(C4N2O4S)3(H2O)](H2O)} (Ln = La (11), Ce (12)), are solvothermally synthesized by reacting the 1,2,5-thiadiazole-3,4-dicarboxylate (H2tdc) ligand with the corresponding lanthanide nitrate. These compounds exhibit three different types of structures which changed from nonporous to open-framework MOFs by adjusting the reaction conditions. Compounds 1–8 (type I) with a moc topology are constructed of 1D zigzag chains and pillared water molecules. Fumaric acid (Fac) as the coligand is introduced in the reaction to replace the pillared water and link similar zigzag chains to assemble compounds 9 and 10 (type II) with a dia topology. Compounds 11 and 12 (type III) with the chiral space group exhibit 1D right/left helical chains along the b axis, and the helical chains alternatively link together to form 3D frameworks with a new (3,4,5)-connected topology. The luminescence study shows that compounds 5, 6, 8 display intense orange, red and green luminescence and exhibit typical Sm3+, Eu3+ and Tb3+ ion emission, respectively. Furthermore, compounds 1, 7, 9 and 11 also exhibit intense green and blue luminescence arising from the H2tdc ligand.

[In(bpydc)(NO3)(DMA)0.5]·(DMA)(H2O)4.5 (JLU-Liu8), [In(bpydc)(HCOO)H2O]·(DMF)2(H2O)3 (JLU-Liu9) and [In(bpydc)Cl]·(DMF)2(H2O)3 (JLU-Liu10), three novel 3D monoatomic indium–organic frameworks, have been synthesized from the 2,2′-bipyridine-5,5′-dicarboxylic acid (H2bpydc) ligand under solvothermal conditions. These three compounds are constructed from the same ligand, but templated using three different anions (NO3−, HCOO− and Cl−), and they exhibit three different 4-connected ung, crb and cbo network topologies. JLU-Liu8 exhibits two types of single-helical chains with opposite helical directions (left-handed and right-handed), all of the left-handed and right-handed helical chains alternate together. In the structure of JLU-Liu9, there are two types of metal–ligand channels: the smaller square channels with dimensions 3.45 A × 4.03 A and the bigger square channels with dimensions of 11.5 A × 11.5 A. JLU-Liu10 displays an interesting feature of double-helical chains: both helical chains are interconnected with each other by sharing indium ions which entangle one spiral shaft. Furthermore, the role of anions in assisting the formation of distinct structures has been discussed. These three compounds display strong luminescence in the solid state at room temperature.

Five hybrid compounds constructed from polyoxometalates, transition metals and organic ligands [Ni2(4,4′-bpy)5(H2O)2][HBW12O40]·5H2O (1), [Ni2(4,4′-bpy)5(Cl)2][H2SiW12O40]·3H2O (2), [Ni2(4,4′-bpy)5(Br)2][H2SiW12O40]·3H2O (3), [SiW12O40]3[Cu2(4,4′-bpy)7]·(H24,4′-bpy)2·4H3O·2H2O (4) and [SiW12O40]3[Cd2(4,4′-bpy)7]·(H24,4′-bpy)2·4H3O·2H2O (5) have been prepared and characterized by IR, UV-vis, XPS, XRD, TG, circular dichroism, second order nonlinear optical (NLO) measurements, photoluminescent measurements and single crystal X-ray diffraction analyses. The X-ray diffraction analyses reveal that the five compounds all exhibit novel framework structures constructed from polyoxometalates, transition metals and organic ligands. The compounds 1, 2, and 3 are isomorphous and compounds 4 and 5 are isomorphous, too. There are two main differences among the first three compounds. The first difference of the three is the central atom of the Keggin ions: it is B atom for compound 1, and Si atom for compounds 2 and 3. The second difference of the three is the monodentate ligand coordinating to the Ni ions: it is water molecule for compound 1, chloride ion for compound 2 and bromide ion for compound 3. The difference between compounds 4 and 5 is the transition metal centre of the frameworks. In addition, compounds 4 and 5 are the first examples of compounds containing both Keggin ion and pseudo-Keggin ion.

Three open frameworks, [Ni(pnta)2]·1.3DMF (1), [Zn2(pnta)3(OH)]·2DMF (2), and [Cd(pnta)2]·3.8DMF (3), were obtained by solvothermal reactions between 6-(pyridin-4-yl)nicotinic acid (Hpnta) and nickel(II), zinc(II) and cadmium(II) nitrate, respectively. Compound 1 is a chiral framework with a fourfold interpenetrated diamondoid network structure and two types of chiral channels. Compound 2 also possesses the fourfold interpenetrated adamantanoid architecture with helical rhombic nanotube-like channels, each of which has two sides of double-layer walls and two other sides of single-layer walls. Compound 3 is a rarely reported double-walled framework with bcu topology. The luminescent properties of compounds 2 and 3 have been studied in the solid state at room temperature.

Five coordination polymers, [Mn2(NBPDC)2(bpp)]n (1), [Co4(NBPDC)4(bpp)2(H2O)5.25]n (2), [Ni(NBPDC)(bpp)(H2O)2]n (3), [Zn(NBPDC)(bpp)]n (4) and [Cd2(NBPDC)2(bpp)]n (5) (NBPDC = 2,2′-dinitro-4,4′-biphenyldicarboxyl acid, bpp = 1,3-bi(4-pyridyl)propane), have been prepared and structurally characterized. In these compounds, NBPDC and bpp exhibit different coordination modes tuned by different metal ions, and construct various architectures by bridging a variety of inorganic building units. Compound 1 presents a hex net with point symbol for net: {36.418.53.6}. Compound 2 shows a self-penetrating ilc topology by linking Co4 clusters with NBPDC and bpp. Compound 3 presents a 2D structure with (4, 4) topology. Compound 4 shows a diamond network with a 5-fold interpenetrating architecture, featuring left-handed and right-handed helix chains. Compound 5 presents a pcu topology by linking rod-shaped secondary building units. The magnetic properties of compounds 1 and 2 have been characterized.

Under hydrothermal conditions, at different pH levels adjusted by H2ox (ox = oxalate, C2O42−) or N2H4, the reactions of Zn(CH3COO)2·2H2O, phthalic/3-nitrophthalic acid, N2H4·H2O and triazole/tetrazole afforded four new Zn2+ coordination polymers as [Zn5(OH)2(Hpth)2(pth)2(trz)2] (pth = phthalhydrazidate, trz = 1,2,4-triazolate) 1, [Zn3(OH)2(Hpth)2(datrz)2] (datrz = 3,5-diamino-1,2,4-triazolate) 2, [Zn2(pth)(atez)2] (atez = 5-aminotetrazolate) 3 and [Zn5(OH)2(ox)(apth)2(datrz)2] (apth = 3-aminophthalhydrazidate) 4. The acylhydrazide molecules H2pth and H2apth in compounds 1–4 originated from the hydrothermal in situ acylation of N2H4 with phthalic/3-nitrophthalic acid. When preparing compound 4, the reduction of –NO2 into –NH2 also occurred besides the acylation, creating finally a new acylhydrazide molecule H2apth. The X-ray single-crystal diffraction analysis revealed that (i) in compounds 1, 3 and 4, Zn2+ and pth/apth aggregate into the 1D endless chains. The triazolate/tetrazolate molecules extend the Zn2+-pth/apth chains into the different layer networks of compounds 1 and 4, and a 3D network of compound 3; (ii) in compound 2, the datrz molecules link the Zn2+ ions into a 2D layer network. Pth acts as the ancillary ligand; (iii) ox from H2ox was introduced into the final framework of compound 4; (iv) the acylhydrazide molecules exhibit three types of existing forms in compounds 1–4: the diketo form, the keto-hydroxyl form, and the dihydroxyl form. Of those, the dihydroxyl form was observed for the first time. The solid-state photoluminescence analysis indicated that only compound 4 emits green light, and the others do not emit light.

The designed organic ligand 5-(3-amino-tetrazole-5-phenoxy)-isophthalic acid (H2atpia) has been successfully prepared and its coordination features have been explored. By the reaction of H2atpia with transition metals, three metal–organic frameworks (MOFs), namely [Cd(atpia)]2 (1), [Cu3O2(atpia)2] (2) and [Mn3(OH)2(atpia)3]·1.25H2O (3) have been synthesized under hydrothermal conditions. All the compounds were fully characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, power X-ray diffraction and single-crystal X-ray diffraction. These three compounds all display new topologies. Compound 1 exhibits a 3D (2,3,10)-connected framework with (4·62)2(412·618·811·104)(4)2 topology. Compound 2 possesses a 2D 3-nodal layer with (416·614·811·104)(43)2(4)2 topology. Compound 3 features a 2D (3,3,8,8)-connected structure with unprecedented (3·42)2(34·46·56·68·73·8) topology. The diverse structures of these three compounds demonstrate that the distinctive coordination modes of different metals have a significant impact on the construction of MOFs. Moreover, the photoluminescence properties of 1 and the magnetic properties of 2 and 3 have been studied and discussed.

Two three-dimensional metal–organic frameworks, [Cd3K(L1)6(H2O)3](OH)(DMF)4 (1) (HL1 = 3-pyrid-4-ylbenzoic acid) and [Cd(L2)2](DMF)(H2O)0.25 (2) (HL2 = 4-pyrid-4-ylbenzoic acid), have been synthesized by using two ligands with different configuration and characterized by X-Ray diffraction and other techniques. Compound 1 shows a nanosize channel which is constructed by interlocked six-fold one-dimensional helical chains with the asymmetrical ligand HL1. Compared with compound 1, compound 2 shows a larger size channel with the symmetrical ligand HL2 in a single set of diamond cage. Nevertheless, the whole structure with the 4-fold interpenetrated diamondoid network leads to the absence of void space. The two compounds exhibit fascinating luminescence because of the interaction between Cd ions and organic ligands.

Under hydrothermal conditions, the simple reactions between metal salts, aromatic polycarboxylic acids (4,4′-diphthalic anhydride ketone, dphahk; 4,4′-sulfoyldiphthalic anhydride, sdpha; pyridine-2,3-dicarboxylic acid, pdca) and N2H4·H2O with or without the presence of phenanthroline·H2O (phen) yielded four di(mono)acylhydrazidate-coordinated Cd2+/Zn2+ compounds as [Cd(DPHKH)(phen)]·1.75H2O 1, [Zn3(DPHKH)2(HDPHKH)2(phen)2]·8H2O 2, [Cd(SDPTH)(phen)(H2O)]·H2O 3 and [Zn(PDH)2(H2O)2] 4 (DPHKH = 4,4′-diphthalhydrazidatoketone hydrazone; SDPTH = 4,4′-sulfoyldiphthalhydrazidate; PDH = pyridine-2,3-dicarboxylhydrazidate). The di(mono)acylhydrazide molecules in the title compounds originated from the hydrothermal in situ acylation reactions of aromatic polycarboxylic acids with N2H4·H2O. It is noteworthy that another kind of hydrothermal in situ reaction was also observed when preparing compounds 1 and 2, namely the nucleophilic addition reaction between the keto group (of dphahk) and N2H4. The photoluminescence analysis indicates that the compounds in the different states (in the solid state or in aqueous solution) may exhibit different emission behaviors.

Five new three/two-fold interpenetrated coordination polymers, namely, [Cd(mfda)(L1)] (1), [Cd(efda)(L1)] (2), [Zn2(mfda)2(L2)]·DMF·H2O (3), [Zn2(efda)2(L2)]·(DMF)0.25, (4) and [Cd2(mfda)2(L2)2]·DMF·H2O (5) (H2mfda = 9,9-dimethylfluorene-2,7-dicarboxylic acid, H2efda = 9,9-diethylfluorene-2,7-dicarboxylic acid, L1 = Methylene bis(3,5-dimethylpyrazole) and L2 = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene), have been synthesized under solvent-thermal conditions with mixed ligands. Compounds 1 and 2 are isostructural and possess two-dimensional (6, 3) layered structures containing two kinds of rings. Three equivalent (6, 3) net interpenetrate in a parallel fashion to form an unprecedented mat-like 2D sheet. Compounds 3 and 4 are almost identical in structure and display threefold interpenetrating α–Po net structures. Compound 5 displays a twofold interpenetrated 3D 6-connected net with α–Po topology. The luminescent properties of these compounds have been studied in the solid state at room temperature.

Three three-dimensional coordination polymers, namely, [NH2(CH3)2][Co2(MDIP)(OH)(H2O)]·C3H7NO·H2O (1), [NH2(CH3)2]2[Mn3(MDIP)2]·2C3H7NO (2), and [NH2(CH3)2][Mg3(MDIP)(HMDIP)(C3H7NO)]·4H2O (3) (DMF = N,N′-dimethylformamide), have been synthesized by the solvothermal reaction of Co(II), Mn(II), or Mg(II) salts with methylenediisophthalic acid (H4MDIP). All compounds have been characterized by thermogravimetric analysis, IR spectroscopy, elemental and single-crystal X-ray diffraction analyses. Complexes 1–3 are anionic frameworks with [NH2(CH3)2]+ ions occupying the voids, built upon tetra-, tri- and asymmetrical trimetallic cores, respectively. In particular, the asymmetrical trinuclear Mg(II) unit in complex 3 was scarcely observed. Topological analyses show that the three compounds possess binodal (4,8)-connected alb topology with a Schlafli symbol of (410.614.84)(45.6)2. Magnetic investigations indicate that antiferromagnetic couplings are dominant in compounds 1 and 2.

Six coordination polymers, [Mn2(nbpdc)2(bib)]n (1), [Co2(nbpdc)2(bib)1.5(H2O)2]n (2), [Ni2(nbpdc)2(bib)1.5(H2O)2]n (3), [Cu3(nbpdc)2(bib)(OH)2]n (4), [Zn2(nbpdc)2(bib)]n (5), and [Cd2(nbpdc)2(bib)(H2O)]n (6), (H2nbpdc = 2,2′-dinitro-4,4′-biphenyldicarboxylic acid, bib = 1,4-bis(imidazol-1-yl)butane), have been prepared and structurally characterized. In these compounds, nbpdc and bib link different secondary building units (SBUs) to construct various architectures based on different metals. Compounds 1 and 5 present a 3D pcu net based on an infinite rod-shaped SBU. Compounds 2 and 3 have the same 2D double-layer structure with a unique {412.52.6} topology, showing an interesting self-penetration feature. Compound 4 presents a 3D framework with hex topology. Compound 6 shows a 3D framework with unprecedented (412.513.63)(48.55.62) topology based on two different unusual infinite and finite SBUs, and has an interesting self-penetrating feature. Therefore, different metal ions influence the final structures of coordination polymers. Magnetic properties of compounds 1 and 4 have been characterized.

Five coordination polymers, Mn4(nbpdc)4(bip)(H2O)2 (1), Co5(nbpdc)4(bip)2(H2O)6(OH)2 (2), Cu5(nbpdc)4(bip)2(H2O)2(OH)2 (3), Zn5(nbpdc)4(bip)2(OH)2 (4), and Cd2(nbpdc)2(bip) (5), (H2nbpdc = 2,2′-dinitro-4,4′-biphenyldicarboxyl acid, bip = 1,5-bis(imidazole)pentane), have been prepared and structurally characterized. In these compounds, nbpdc and bip link different secondary building units (SBUs) to construct a variety of architectures based on different metals. Compound 1 presents a 3D hex net based on infinite rod-shaped SBUs. Compound 2 shows a 3D framework with mab topology based on Co5 clusters and exhibits an interesting self-penetration feature. Compound 3 presents a 3D framework with pcu topology constructed by Cu5 clusters. Compound 4 is a 3D framework with pcu topology based on infinite rod-shaped SBUs. Compound 5, like compound 4, also exhibits pcu topology constructed by rod-shaped SBUs, but they both possess different structures. The magnetic properties of compounds 1 and 2 have been characterized.

A novel metal–organic framework [Cu3(m-TATB)2Py(CH3OH)2] (1) constructed of a triazine-based trigonal-planar ligand, 3,3′,3″-s-triazine-2,4,6-triyltribenzoate (m-H3TATB), has been synthesized and structurally characterized. Compound 1 features three-dimensional (3D) channels and cavities together, and exhibits high carbon dioxide sorption at normal pressure.

A novel metal–organic framework with unprecedented interweaving of coaxial single-helical and equal double-helical chains of opposite chirality, which features a super-connective helix simultaneously tangling with eight helices, was reported.

Three 2D layered zinc coordination polymers: Zn(trz)(HBDC) (1), Zn4(trz)4(4-FBA)4·(H2O)0.5 (2) and Zn4(trz)4(4-CBA)4 (3) (trz = 1,2,4-triazole, H2BDC = 1,3-benzenedicarboxylic acid, 4-HFBA = 4-fluorobenzoic acid and 4-HCBA = 4-chlorobenzoic acid) have been synthesized by hydrothermal reactions and characterized by IR, elemental analysis, TGA measurements and X-ray single-crystal analysis. Compounds 1–3 have the same 2D layer constructed by zinc(II) with trz and carboxylate. The main difference in the structure of the three compounds is the interactions between the layers. Compound 1 shows unusual intermolecular hydrogen bonding and C–O⋯π interactions, compound 2 exhibits intermolecular hydrogen bonding and C–F⋯π interactions, while compound 3 only shows intermolecular C–Cl⋯π interactions. It is found that the noncovalent intermolecular interactions have an influence on crystal packing.

Hydrothermal reactions between mixed ligands (4,4′-oxybis(benzoate) and 1,3-bis(4-pyridyl)propane) and Co(NO3)2·6H2O afford two novel helical metal–organic networks Co(C14H8O5)(C13H14N2) 1 and Co(C14H8O5)(C13H14N2)·H2O 2. Compound 1 has a 2-D layer network and the main body of the layer is composed of alternate right-handed and left-handed helical chains by sharing cobalt ions. The distance of the repeating parts of the helical chains is ca. 10.0 A and the size of the helical channels is ca. 7.0 × 7.0 A. In contrast, compound 2 has a 2-D interpenetrated double-layer network and each monolayer is composed of homochiral helical chains by sharing cobalt ions. The distance of the repeating parts of the helical chains is ca. 12.1 A and the size of the helical channels is ca. 7.0 × 7.0 A. Interestingly, each helical chain of 2 is constructed by alternate (4,4′-oxybis(benzoate) and 1,3-bis(4-pyridyl)propane) and cobalt ions. Moreover, two independent monolayers constructing a double-layer are assembled in a homochiral fashion and adjacent double-layers exhibit opposite chirality. The magnetism analysis indicated that compounds 1 and 2 show antiferromagnetic exchange interaction.

Two new metal–organic frameworks [Cd3(H2O)2(C5N2O4H)2·H2O] 1 and [KCd(C7N2O4H5)] 2 have been hydrothermally synthesized employing 4,5-imidazoledicarboxylic acid (IMDC) and 2-ethyl-4,5-imidazoledicarboxylic acid (2-EtIMDC) as organic ligands. The single-crystal structure analysis reveals that compound 1 exhibits a 3-D framework, which is generated from 2-D layers pillared by 1-D chains along the c-axis. Compound 2 presents a 3-D structure with 1-D channels, which are connected in a cross-like fashion by [CdN2O3] trigonal bipyramid units and 2-EtIMDC ligands.

The coordination polymer of copper(I) iodide Cu4I4(DABCO)2 (DABCO = 1,4-diazabicyclo-[2.2.2]octane) was prepared by solvothermal methods, and its structure was determined by single-crystal X-ray diffraction. The structure contains a novel 654 topology and displays interesting self-penetration.