Six new coordination polymers, namely, {[Mn2(L1)(bpfp)(H2O)2]·6H2O·(CH3OH)}n (1), {[Mn4(μ3-O)2(L1)2(bpe)2(H2O)2]·2H2O}n (2), [Ni(HL1)(Hbpmp)(H2O)2]n (3), [Co2(μ2-OH)(HL1)(bpmp)(H2O)4]n (4), {[Co2(L2)(bpfp)(H2O)2]·4H2O}n (5), {[Co2(L2)2(bpe)2(H2O)2·2H2O]·(NH4)4}n (6) (H4L1 = [1,1′:4′,1′′-terphenyl]-2,2′′,5,5′′-tetracarboxylic acid, H4L2 = [1,1′:4′,1′′-terphenyl]-3,3′′,5,5′′-tetracarboxylic acid, bpfp = bis(4-pyridylformyl)piperazine, bpe = 1,2-bis(pyridin-4-yl)ethane and bpmp = N,N′-bis(4-pyridyl)piperazine) were synthesized under hydrothermal conditions by terphenyl tetracarboxylates, bis-pyridyl ligands and transition metal salts. These six complexes were characterized by elemental analysis, infrared (IR) spectroscopy, thermogravimetric analysis (TGA), single-crystal X-ray diffraction, powder X-ray diffraction (PXRD) and fluorescence spectroscopy. Complexes 1 and 5 possess three-dimensional (3D) (4,6)-connected networks with {43·63}2{46·66·83} and {44·610·8}{44·62} topologies, respectively. Complexes 2–4 and 6 feature two-dimensional (2D) networks, which are expanded into 3D supramolecular frameworks via hydrogen bonding interactions. Desorption of lattice water molecules in complexes 1 and 2 was analyzed, and the values of water vapor uptake are 15.17 mL g−1 and 27.24 mL g−1, respectively.

Five coordination polymers, namely, Zn(dpd)(bpy)0.5 (1), Zn(Hdpd)2(bpy)2·H2O (2), Co3(Hdpd)2(dpd)2(bpy)3(H2O)2·2H2O (3), Co(Hdpd)2(bpy)(H2O)2·2H2O (4) and Ni(Hdpd)2(bpy)(H2O)2·2H2O (5) (H2dpd = 2,4-diphenyl ether dicarboxylic acid, bpy = 4,4′-bipyridine) with zero-(0D), one-(1D), two-(2D) and three-dimensional (3D) structures have been synthesized under similar hydrothermal conditions using H2dpd, bpy and different transition metal salts. Compound 1 possesses a 3D framework with a {4·82}{4·82·103} topology. Compound 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. Compound 3 is made up of a 2D ladder network with {4·62}2{42·62·82} topology, which consists of 1D ladder-like chains. Compounds 4 and 5 are isostructural and feature 1D chains which are further connected by hydrogen bonding interactions to form 2D supramolecular structures. These compounds have been characterized using elemental analysis, infrared (IR), thermal gravimetric analysis (TGA), and single crystal X-ray diffraction. Furthermore, the fluorescence properties of 1–5 have been investigated. Water vapor sorption studies reveal that compounds 3, 4 and 5 exhibit very good water vapor uptakes (100.71 ml g−1 for 3, 109.94 ml g−1 for 4 and 108.96 ml g−1 for 5). Magnetic susceptibility measurements indicate that compounds 3 and 4 show antiferromagnetic interactions, while compound 5 shows ferromagnetic behavior.

Eight coordination polymers, namely, Mn(cob)(phen) (1), Co(cob)(phen)2(H2O)·5H2O (2), Co(cob)(phen) (3), Cd(cob)(phen) (4), Mn(cob)(bpy)(H2O)2 (5), Co(cob)(bpy)(H2O)2 (6), Cu(Hcob)2(bpy)(H2O)2·H2O (7), Cd(cob)(bpy) (8) (H2cob = 2-[(4′-carboxybenzyl)oxy]benzoic acid, phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine) have been synthesized under hydrothermal conditions by H2cob, different N-donor ligands and transition metal salts. These eight complexes have been characterized by elemental analysis, infrared (IR) spectroscopy, thermogravimetric analysis (TGA), and single-crystal X-ray diffraction. Complexes 1, 3 and 4 are isostructural and feature two-dimensional (2D) wave-like layer networks, which are further interconnected by inter-layer π⋯π stacking interactions to form three-dimensional (3D) supramolecular structures. Complexes 2 and 7 are both mononuclear structures which are further self-assembled through hydrogen bonding and π⋯π stacking interactions to generate 3D supramolecular structures. Complexes 5 and 6 are isostructural and show one-dimensional (1D) zigzag chains, which are further connected by hydrogen bonding to form a 2D supramolecular structure. Complex 8 is an infinite 1D linear structure. Desorption of lattice water molecules in complexes 2, 5 and 6 was analyzed, and demonstrates that these water molecules may influence the construction of the final structures. The water sorption studies reveal that complexes 2, 5 and 6 exhibit good water vapor uptake (64.12 ml g−1 for 2, 40.26 ml g−1 for 5 and 55.34 ml g−1 for 6). Furthermore, the fluorescence properties of 1–8 have been investigated. Magnetic susceptibility measurements indicate that complexes 1–3 show weak antiferromagnetic behavior, while 5–6 exhibit ferromagnetic behavior.

Three novel homochiral helical metal−organic frameworks (MOFs), namely [Zn(LTP)2]n (1), [Cd(LTP)2]n (2), and [Ni(LTP)2]n (3) (LTP = l-thioproline), have been synthesized and characterized. X-ray crystallographic analysis shows that all the three complexes consist of homochiral left-handed or right-handed helical chains. Complex 1 exhibits 1-D Zn-carboxyl right-handed helical chains constructed by pentacoordinated Zn2+ ions. Complex 2 shows a 2-D homochiral coordination framework with (4, 4) topology based on Cd-carboxyl right-handed helical chains in which Cd2+ ions are 6-fold coordinated. There are various hydrogen bonds between the adjacent helical chains in 1 and 2 which connect them into 3-D supramolecular networks. Complex 3 also exhibits a 2-D homochiral layer structure with (4, 4) topology containing Ni-carboxyl left-handed helical chains. The luminescence properties of 1 and 2 have been investigated briefly.

The eight-nickel-capped polyoxoazonickelate, [Ni20(OH)24(MMT)12(SO4)](NO3)2·6H2O (1; MMT = 2-mercapto-5-methyl-1,3,4-thiadiazole), has been synthesized, which has an α-Keggin structure with eight nickel caps. In this structure, the polyatom is the late transition metal NiII; the central heteroatom is S, and the organic terminal ligand becomes the primary part of the Keggin structure. This is a Keplerate-type cluster, which shows a central NiII12 cuboctahedron formed by the 12 NiII centers of the classical α-Keggin core and a NiII8 hexahedron formed by the eight nickel caps.

Three new polyoxometalates X7[PMo8O30] (X=Na+, 1; K+, 2; NH4+, 3) have been synthesized with the classical Keggin and/or Dawson heteropolymolybdophosphates and PCl5 in acetonitrile-water solutions via hydrothermal treatment. The three compounds were characterized by different analyses including IR, 31P NMR spectroscopy, elemental analysis, electrochemistry, thermogravimetric analysis (TGA) and powder X-ray diffraction (XRD). Single crystal X-ray analyses were carried out on Na7[PMo8O30] (1) and (NH4)7[PMo8O30] (3). Compound 1 and 3 crystallize in the orthorhombic system. The structure of compound 2 was confirmed by the IR spectra and powder XRD. All the three compounds contain the same octamolybdophosphate polyoxoanion [PMo8O30]7−, which consists of two Mo4O15 moieties linked by one central PO4 tetrahedron, leading to a remarkable sandglass-like structure.with the Keggin and/or Dawson heteropolymolybdophosphates and PCl5 in acetonitrile–water solutions via hydrothermal treatment, three new polyoxometalates X7[PMo8O30] (X=Na+, 1; K+, 2; NH4+, 3) have been synthesized and characterized. Single crystal X-ray analyses were carried out on Na7[PMo8O30] (1) and (NH4)7[PMo8O30] (3). All the three compounds contain the new sandglass-like structure [PMo8O30]7−.