•Two new Co(II) complexes have been synthesized under the same reaction conditions.•1 exhibits 3D 2-fold interpenetration framework with pcu net and 2 displays 3D 4-fold [2 + 2] interpenetration framework with dia net.•Two different complexes result from different auxiliary ligands.•Complexes 1 and 2 display weak antiferromagnetic properties.Two new coordination polymers, {[Co(bib)0.5(bdc-Br2)]·CH3OH}n (1) and {[Co(bib)(1,4-ndc)]·0.5H2O}n (2) have been synthesized. The results of X-ray crystallographic analysis show that compound 1 exhibits a 6-connected three-dimensional (3D) 2-fold interpenetrated architectures with the point symbol of 412.63, 2 displays a 4-connected 3D 4-fold [2 + 2] interpenetrated structures with the point symbol of 66. The formulas of 1 and 2 were determined by X-ray crystallography, elemental analysis, and thermogravimetric analysis (TGA). In addition, the compounds 1 and 2 reveal antiferromagnetic interactions.Two novel 3D CPs, namely, {[Co(bib)0.5(bdc-Br2)]·CH3OH}n (1) and {[Co(bib)(1,4-ndc)]·0.5H2O}n (2). 1 exhibits a 3D 2-fold interpenetrated structures with the point symbol of 412.63 and 2 displays a 3D 4-fold [2 + 2] interpenetrated structures with the point symbol of 66. The magnetism studies show that complexes 1 and 2 display weak antiferromagnetic properties.Download high-res image (162KB)Download full-size image

On the basis of a temperature-induced effect, the solvothermal reaction of Co(Ac)2·4H2O, 5-amino-2,4,6-triiodoisophthalic acid (H2atibdc), and 1,4-bis(2-methyl-imidazol-1-yl)butane (bib) at 80 °C gave a new coordination polymer [Co(bib)(atibdc)] (1), which shows a two-dimensional (2D) network with left- and right-handed helical chains. By raising the reaction temperature to 130 °C, a pair of homochiral enantiomers [Co(bib)(atibdc)]·2H2O (2, 2M, and 2P) were successfully obtained, displaying a three-dimensional (3D) framework with three kinds of unique helical chains. Keeping the temperature of the reaction system to 150 °C, excited, an in situ iodine elimination reaction occurred, and a new linker 5-aminoisophthalic acid (H2aipa) was generated, which then cooperated with the bib ligand to construct a coordination polymer [Co(bib)(aipa)] (3), showing a 3D 3-fold interpenetrating architecture. The comparison of final solid structures exhibits an exclusive temperature-induced effect on the construction of the coordination polymer. Furthermore, via a single-crystal-to-single-crystal (SCSC) transformation, the 2D network of 1 can be derived from the 3D framework of 2, which presents a rare type of temperature-solvent induced SCSC transformation. In addition, the magnetic properties of 1–3 have been investigated as well.

Two novel zinc(II) coordination polymers, [Zn2(bib)(5-Br-ipa)2]}n (1) and {[Zn(bib)(2,6-ndc)]}n (2) (bib = 1,4-bis(2-methyl-imidazol-1-yl)butane, 5-Br-H2ipa = 5-bromoisophthalic acid, 2,6-H2ndc = 2,6-naphthalenedicarboxylic acid) have been synthesized under the same solvothermal conditions and characterized by elemental analysis, IR spectroscopy, single crystal X-ray diffraction technology. Complex 1 shows a novel 3-fold interpenetrating architecture possessing a couple of single helices and a pair of rare tri-flexural helices. Complex 2 gives an unusual 2D + 2D → 3D inclined polycatenation architecture comprised of two sets of interlocked equivalent 2D layers. The fluorescent properties of complexes 1 and 2 were studied. In addition, the thermal decompositions of 1 and 2 were investigated by simultaneous TG/DTG–DSC techniques. The TG curves exhibit that complexes 1 and 2 possess good thermostability up to 320 °C and 315 °C, respectively. The enthalpy of the melting decomposition (ΔHd) was measured. The apparent activation energy E and the pre-exponential factor (A) of skeleton collapse for the complexes were calculated by the integral Kissinger’s method and Ozawa–Doyle’s method. The thermodynamic parameters (ΔH≠, ΔG≠, and ΔS≠) at the peak temperatures of the DSC curves were calculated. The structural stability could be illustrated from the point of thermodynamics and kinetics.(1) Two novel zinc coordination architectures constructed from the primary ligand bib, Zn(II) transition metal ions and two carboxylate coligands. (2) The thermal decompositions properties of 1 and 2 were investigated by a simultaneous TG/DTG–DSC technique. The apparent activation energy E and the pre-exponential factor (A) of skeleton collapse for the complexes 1 and 2 are calculated by the integral Kissinger’s method and Ozawa–Doyle’s method. The structural stability could be illustrated from the point of thermodynamics and kinetics.

Seven new mixed–ligand coordination polymers, {[Co0.5(bib)0.5(tftpa)0.5]·0.5H2O}n (1), [Cd2(bib)(tftpa)2]n (2), [Ni0.5(bib)0.5(tftpa)0.5]n (3), {[Co0.5(tftpa)(H2O)]·0.5bib·EtOH}n (4), {[Cd0.5(tftpa)(H2O)]·0.5bib·EtOH}n (5), [Cd3(bib)3(tftpa)3(MeOH)3]n (6), and [Cd(bib)(tftpa)(MeOH)]n (7) (bib = 1,4-bis(2-methylimidazol-1-yl)butane, H2tftpa = tetrafluoroterephthalic acid) have been synthesized under different reaction conditions and characterized by elemental analysis, IR, PXRD, single crystal X-ray diffraction analysis and thermogravimetric analysis. Complex 1 exhibits an unusual [2 + 2] interpenetrating diamond framework belonging to class IIIa with the point symbol 66. Complex 2 reveals a (3,4)-connected 3D framework with a unique double-stranded helical chain based on Cd–O–Cd and Cd–(COO)–Cd. Complex 3 presents a 4-fold interpenetrating 3D diamond framework belonging to class Ia with the point symbol 66. Complexes 4 and 5 display a 3D supramolecular architecture built on 2D stacked layers through hydrogen bonding and π–π interactions. Complex 6 also shows a 3D 4-fold interpenetrating diamond framework belonging to class Ia with the point symbol 66. Complex 7 features a 2D + 2D → 2D parallel polycatenated framework with the point symbol 44·62. The structural diversity of complexes 1–7 illustrate that a subtle change can have a marked effect on the crystal architectures. Moreover, the magnetic properties of complexes 1, 3, and 4, and the solid-state photoluminescence results for complexes 2, and 5–7 were also studied.

To further investigate the influence of solvent in the self-assembly process, four new solvent-controlled isomeric Ni(II) coordination polymers based bib and 5-Br-H2ip ligands, namely, [Ni(bib)(5-Br-H2ip)(CH3CH2OH)]n (1), [Ni(bib)(5-Br-H2ip)]n (2), {[Ni2(bib)(5-Br-H2ip)2(H2O)]·0.5H2O}n (3), {[Ni(bib)(5-Br-H2ip)]·DMA}n (4) (bib = 1,4-bis(2-methylimidazol-1-yl)butane, 5-Br-H2ip = 5-bromoisophthalic acid) were prepared under the same reaction conditions except with diverse solvent systems. Their EA, IR, PXRD, single crystal XRD analysis and TG analysis have been characterized. As controlled different solvent systems, complex 1 exhibits an unusual [2 + 2] dia construction with the point symbol 66. Complex 2 shows a 3D non-interpenetrated dia structure with the point symbol 66. Complex 3 features a dinuclear 3D pillar-layer pcu network with the point symbol of 412·63. Complex 4 displays a 2D stacked layer sql net with the point symbol 44·62. The results demonstrate that solvent has a significant effect on the final structure of coordination polymers. Furthermore, the magnetic properties of complexes 1–4 have also been studied.

Three new 4-fold interpenetrated coordination polymers based on two different dia interpenetrating modes have been prepared successfully, namely [Cu0.5(bib)0.5(tftpa)0.5]n (1), {[Zn0.5(bib)0.5(tftpa)0.5]·0.5H2O}n (2) and [Cd(bib)(tftpa)(EtOH)]n (3) (bib = 1,4-bis(2-methyl-imidazol-1-yl)butane, H2tftpa = tetrafluoroterephthalic acid). Complexes 1 and 3, with the same octahedral metal center, are obtained as 4-fold interpenetrated dia coordination frameworks; however, complex 2, with a tetrahedral metal center, presents a 4-fold dia network with an uncommon [2 + 2] mode of interpenetration. All of the polymers contain right- and left-handed helices that are constructed alternatively and each helix is built up from [M2(tftpa)(bib)]n. Additionally, thermogravimetric curves and luminescent emissions of 2 and 3 have been studied.Three 4-fold interpenetration coordination polymers based on two different dia interpenetrating modes have been synthesized using the rigid tetrafluoroterephthalic acid and the flexible 1,4-bis(2-methyl-imidazol-1-yl)butane ligands through solvothermal or diffusion methods. All of the polymers contain the same right- and left-handed helices that are constructed alternatively and each helix is built up from [M2(tftpa)(bib)]n.

Two isomeric metal–organic frameworks, consisting of Co-triazolate layers and positional isomeric dicarboxylate pillars, both show distinct temperature-dependent CO2 sorption behaviors. Because of the pores functionalized by amino groups, both materials have high CO2 uptake and highly selective sorption of CO2 over CH4 and N2.

Five new solvent-induced cadmium coordination architectures, {[Cd(bib)(5-Br-H2ip)]·EtOH}n (1), {[Cd0.5(bib)0.5(5-Br-H2ip)0.5]·3H2O}n (2), {[Cd2(bib)(5-Br-H2ip)2(MeOH)]}n (3), {[Cd(bib)0.5(5-Br-H2ip)(H2O)2]·H2O}n (4), and {[Cd(bib)0.5(5-Br-H2ip)(H2O)]}n (5), have been constructed from the same materials (1,4-bis(2-methyl-imidazol-1-yl)butane (bib), 5-bromoisophthalic acid (5-Br-H2ip) and Cd(Ac)2·2H2O) under different reaction solvents. As controlled by solvent systems, compound 1 shows a 3-fold interpenetrating 3D framework based on the left- and right-handed helical chains, while compound 2 reveals a 3-fold interpenetrating 3D network and each single net is based on the left-handed, right-handed and meso-helical chains. Compound 3 is a 3D framework that can be simplified as a 6-connected net with (48·62) topology. Both 4 and 5 display 3D supramolecular frameworks through weak aromatic π–π stacking interactions and hydrogen bonding interactions. However, the topologies of 4 and 5 are definitely different. Compound 4 presents a 3-connected net with (82·10) topology, while compound 5 reveals a 4-connected net with (42·63·8) topology. The effects of solvents on the crystal structures were discussed and thermogravimetric analysis and solid-state photoluminescence results for 1–5 were investigated.

•Two complexes have been synthesized.•Complex 1 displays a 3D 8-fold interpenetration network while complex 2 shows a 2D layer.•Variable-temperature magnetic investigations for 1 have been discussed.Two new Co(II) and Cu(II) complexes, {[Co(bib)(4,4 ′-sdc)]}n (1), and {[Cu(bib)(4,4′-sdc)·4H2O]}n (2) (bib = 1,4-bis(2-methyl-imidazol-1-yl)butane, 4,4′-sdc = 4,4′-stilbenedicarboxylic acid), have been synthesized under similar reaction conditions. These newly synthesized complexes were characterized by single-crystal X-ray diffraction, elemental analysis, and thermogravimetry. The magnetic susceptibility of complex 1 was also investigated. Complex 1 displays a 3D 8-fold interpenetration network in the [4 + 4] manner. However, complex 2 reveals a 2D layered architecture constructed by linking the meso-helical chains to the 4,4′-sdc ligands.Two new Co(II) and Cu(II) complexes constructed by mixed ligands bib and H2sdc have been synthesized under the same synthetic conditions. The structures of the two are definitely different. Complex 1 features a 3D 8-fold interpenetration network in the [4 + 4] manner. However, complex 2 shows a two-dimensional (2D) sheet architecture constructed by linking the meso-helical chains to the 4, 4′-sdc ligands.

By employing the mixed-linker synthetic strategy, two new cobalt(II) cluster-based frameworks, [Co2.5(btc)(atz)2(Hatz)(DMF)]·2DMF (1) and [Co2.5(btc)(Hbtc)0.5(atz)(CH3CN)(H2O)]·H2O (2), constructed from the same initial materials Co(NO3)2, 1,3,5-benzenetricarboxylic acid (H3btc) and 3-amino-1,2,4-triazole (Hatz), have been synthesized by solvothermal reactions. Crystal-structure analyses demonstrated that 1 and 2 are three-dimensional (3D) porous frameworks based on Co-triazolate chain/layer and tricarboxylate pillars. Thermogravimetric analysis (TGA) and power X-ray diffraction (PXRD) measurements showed that both of them have high thermal stability and good water stability. Remarkably, both the structures of desolvated 1 and 2 contain suitable pore sizes and highly polar channel systems functionalized by amino groups, open metal sites, carbonyl or free carboxylic acid sites and uncoordinated triazolate nitrogen atoms on the pore surfaces, exhibiting multipoint interactions between CO2 molecules and frameworks, resulting in high CO2 uptake and selectivity for CO2 over N2.

Two novel entangled coordination polymers, [Zn(abda)(bimh)]n (1) and [Cd(dtba)(bimh)]n (2) (H2abda = azobenzene-4,4′-dicarboxylic acid, H2dtba = 2,2′-dithiobisbenzoic acid, bimh = 1,6-bis(2-methylimidazole-1-yl)hexane), have been synthesized using long mixed ligands. Complex 1 features rare 2D parallel interpenetrated 44-sql networks which show the same handedness. Interestingly, in the interpenetrating nets, A-chains [Zn(bimh)]n of one layer co-use the helical shaft with B-chains [Zn(abda)]n of the other layer of double-layers. Complex 2 shows a unique 3D 3-fold interpenetrating homochiral 86 network, and each single net is constructed from right-handed [Cd(dtba)]n single helices and left-handed [Cd(bimh)]n double-stranded helices.

An unprecedented 3D entangled framework, {[Co(bib)(hoip)]·6H2O}n (1), has been synthesized by using rigid and flexible mixed-ligands, which represents to the best of our knowledge, the first example of one-fold inclined 1D → 3D polycatenated networks built by the vertical interlocking of novel interweaving triple-stranded helices sharing the same CoII nodes.

Highlights•Four Zn(II) complexes have been synthesized via mixed ligands strategy.•All of them contain meso-helical chain constructed by metal center and bib ligand.•Luminescent spectra have been also investigated.On the basis of 1,4-bis(2-methyl-imidazol-1-yl)butane (bib), four new coordination polymers (CPs), namely, {[Zn(bib)(male)]2·2H2O}n(1), {[Zn(bib)(suc)]·H2O}n(2), {[Zn(bib)(fum)]·CH3OH}n(3), {[Zn(bib)(bpdc)]·2H2O}n(4) (H2mal = maleic acid, H2suc = succinic acid, H2fum = fumaric acid, bpdc2- − = 2,2’2′-bipyridine- 3,3’3′-dicarboxylate) have been synthesized by the reaction of zinc(II) salts and bib with four different aliphatic/aromatic binary acids under the same conditions, respectively. These coordination polymers are structurally characterized by elemental analysis, IR, single-crystal X-ray crystallography and TG analysis. All of them host a same meso-helical chain constructed by metal centers and bib ligands. 1 and 2 feature similar 2-D wave-like topology containing a meso-helical chain; 3 is a 3-D diamond-like structure, comprising two different meso-helical chains, and shows 4-fold interpenetrated framework with {6^6} topology; 4 is a 3-D diamond-like structure, containing a meso-helical chain, and displays 3-fold interpenetrated net with {6^6} topology. In addition, the phase purities of bulk samples were further identified by X-ray powder diffraction analysis. Solid state luminescent spectra have been investigated at room temperature, and the luminescent lifetime of 3 was monitored at room temperature.Graphical abstractFour new complexes containing a same meso-helical chain constructed by Zn(II) ions and bib ligands have been synthesized. 1 and 2 feature similar 2D wave-like topology; 3 shows 4-fold interpenetrated 3D framework with {6^6} topology; 4 displays 3-fold interpenetrated 3D net with {6^6} topology.

The chiral diamondoidlike Cd(II) containing coordination polymer {[Cd(oba)(bib)]·2H2O}n (1) (oba = 4,4′-oxybis(benzoate), bib = 1,4-bis(2-methyl-imidazol-1-yl)butane) is reported; the 3D networks interpenetrate fivefold, nevertheless leave cavities capable of including sizable guest molecules. This compound also exhibits high thermal stability and blue-shift emission, and can be explored for potential blue luminescent materials.An novel diamondoidlike coordination polymer {[Cd(oba)(bib)]·2H2O}n (1) have been synthesized. Interestingly, the compound still exhibits significant void space that may be filled with guest H2O molecules in spite of the fivefold interpenetration that occurs in the solid. Besides, this compound also exhibits high thermal stability and blue-shift emission, and can be explored for potential blue luminescent materials.

Three coordination polymers containing 2-(2-pyridyl)benzimidazole (PyHBIm) ligand, namely {[Zn3(PyBIm)3(PyHBIm)2(tma)(H2O)]•H2O}n (1), [Zn(PyHBIm)(oba)]n (2), [Cd(PyHBIm)(oba)]n (3), (tma = trimesate, oba = 4,4′-oxybis-(benzoate)), have been prepared through hydrothermal reaction. Compound 1 exhibits one-dimensional (1D) helical structure. However, compounds 2 and 3 display 1D meso-helical structure. These 1D structures are further assembled into three-dimensional (3D) networks through aromatic π–π stacking interactions and hydrogen bonding interactions. Moreover they all exhibit strong photoluminescence at room temperature and may be good candidates for potential luminescence materials.Three new coordination polymers containing 2-(2-pyridyl)benzimidazole (PyHBIm) ligand, namely {[Zn3(PyBIm)3(PyHBIm)2(tma)(H2O)]•H2O}n (1), [Zn(PyHBIm)(oba)]n (2), [Cd(PyHBIm)(oba)]n (3), (tma = trimesate, oba = 4,4′-oxybis(benzoate)), have been prepared through hydrothermal reaction. They exhibit two different kinds of 1D helical structures. Compound 1 exhibits 1D helical structure. However, compounds 2 and 3 display 1D meso-helical structure.

By employing the mixed-linker synthetic strategy, two new cobalt(II) cluster-based frameworks, [Co2.5(btc)(atz)2(Hatz)(DMF)]·2DMF (1) and [Co2.5(btc)(Hbtc)0.5(atz)(CH3CN)(H2O)]·H2O (2), constructed from the same initial materials Co(NO3)2, 1,3,5-benzenetricarboxylic acid (H3btc) and 3-amino-1,2,4-triazole (Hatz), have been synthesized by solvothermal reactions. Crystal-structure analyses demonstrated that 1 and 2 are three-dimensional (3D) porous frameworks based on Co-triazolate chain/layer and tricarboxylate pillars. Thermogravimetric analysis (TGA) and power X-ray diffraction (PXRD) measurements showed that both of them have high thermal stability and good water stability. Remarkably, both the structures of desolvated 1 and 2 contain suitable pore sizes and highly polar channel systems functionalized by amino groups, open metal sites, carbonyl or free carboxylic acid sites and uncoordinated triazolate nitrogen atoms on the pore surfaces, exhibiting multipoint interactions between CO2 molecules and frameworks, resulting in high CO2 uptake and selectivity for CO2 over N2.