Fabrication of Carboxylate-Functionalized 2D MOF Nanosheet with Caged Cavity for Efficient and Selective Extraction of Uranium from Aqueous Solution.

The efficient removal of radioactive uranium from aqueous solution is of great significance for the safe and sustainable development of nuclear power. An ultrathin 2D metal-organic framework (MOF) nanosheet with cavity structures was elaborately fabricated based on a calix[4]arene ligand. Incorporating the permanent cavity structures on MOF nanosheet can fully utilize its structural characteristics of largely exposed surface area and accessible adsorption sites in pollutant removal, achieving ultrafast adsorption kinetics, and the functionalized cavity structure would endow the MOF nanosheets with the ability to achieve preconcentration and extraction of uranium from aqueous solution, affording ultrahigh removal efficiency even in ultra-low concentrations. Thus, more than 97% uranium can be removed from the concentration range of 50-500 µg L-1 within 5 min. Moreover, the 2D nano-material exhibits ultra-high anti-interference ability, which can efficiently remove uranium from groundwater and seawater. The adsorption mechanism was investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) analysis, and density functional theory (DFT) calculations, which revealed that the cavity structure plays an important role in uranium capture. This study not only realizes highly efficient uranium removal from aqueous solution but also opens the door to achieving ultrathin MOF nanosheets with cavity structures, which will greatly expand the applications of MOF nanosheets.

Decorating Cage-Shaped Cavities with Carboxyl Groups on Two-Dimensional MOF Nanosheet for Trace Uranium(VI) Trapping.

The efficient and complete extraction of uranium from aqueous solutions is crucial for safeguarding human health from potential radiotoxicity and chemotoxicity. Herein, an ultrathin 2D metal-organic framework (MOF) nanosheet with cavity structures was elaborately constructed, based on a calix[4]arene ligand. The large molecular skeleton and cup-shaped feature of the calix[4]arene enabled the as-prepared MOFs with large layer separations, which can be readily delaminated into ultrathin single-layer (∼1.25 nm) nanosheets. The incorporation of permanent cavity structures to the MOF nanosheets can fully utilize their structural features of readily accessible adsorption groups and exposed surface area in uranium removal, reaching ultrafast adsorption kinetics; the functionalized cavity structure endowed MOF nanosheets with the ability to preconcentrate and extract uranium from aqueous solutions with ultrahigh efficiencies, even at extremely low concentrations. As a result, relatively high removal ratios (>95%) can be achieved for uranium within 5 min, even in the ultralow concentration range of 75-250 ppb, and the residual uranium was reduced to below 4.9 ppb. The MOF nanosheets also exhibited extremely high anti-interference ability, which could efficiently remove the low-level uranium (∼150 ppb) from various real samples. The characterizations and density functional theory calculations demonstrated that the synergistic effects of multiple interactions between the carboxylate groups and cage-like cavities with uranyl ions can be responsible for the efficient and selective uranium extraction.

Luminescent Two-Dimensional Metal-Organic Framework Nanosheets with Large π-Conjugated System: Design, Synthesis, and Detection of Anti-Inflammatory Drugs and Pesticides.

Two-dimensional (2D) metal-organic framework (MOF) nanosheets, with largely exposed surface area and highly accessible active sites, have emerged as a novel kind of sensing material. Here, a luminescent 2D MOF nanosheet was designed and synthesized by a facile top-down strategy based on a three-dimensional (3D) layered MOF {[Zn(H2L)(H2O)2]·H2O}n (Zn-MOF; H4L = 3,5-bis(3',5'-dicarboxyphenyl)-1H-1,2,4-triazole). With a large π-conjugated system and rigid planar structure, ligand H4L was elaborately selected to construct the bulk Zn-MOF, which can be readily exfoliated into 2D nanosheets, owing to the weak interlayer interactions and easy-to-release H2O molecules in the interspaces of 2D layers. Given the great threat posed to the ecological environment by anti-inflammatory drugs and pesticides, the developed luminescent Zn-MOF nanosheets were utilized to determine these organic pollutants, achieving highly selective and sensitive detection of diclofenac sodium (DCF) and tetramethylthiuram disulfide (TMTD). Compared to the detection limits of 3D Zn-MOF (7.72 ppm for DCF, 6.01 ppm for TMTD), the obviously lower detection limits for 2D Zn-MOF nanosheets toward DCF (0.20 ppm) and TMTD (0.18 ppm) further revealed that the largely exposed surface area with rigid planar structure and ultralarge π-conjugated system greatly accelerated electron transfer, which brought about a vast improvement in response sensitivity. The remarkable quenching performance for DCF and TMTD stems from a combined effect of photoinduced electron transfer and competitive energy absorption. The possible sensing mechanism was systematically investigated by the studies of powder X-ray diffraction, UV-vis, luminescence lifetime, and density functional theory calculations.

Fabrication of Protonated Two-Dimensional Metal-Organic Framework Nanosheets for Highly Efficient Iodine Capture from Water.

Radioactive iodine (129I and 131I), produced or released from nuclear-related activities, posed severe effects on both human health and environment. The efficient removal of radioiodine from aqueous medium and vapor phase is of paramount importance for the sustainable development of nuclear energy. Herein, a metal-organic framework (MOF) nanosheet with a positive charge was constructed for the capture of iodine for the first time. The as-synthesized ultrathin nanosheets, with a thickness of 4.4 ± 0.1 nm, showed a record-high iodine adsorption capacity (3704.08 mg g-1) from aqueous solution, which is even higher than that from the vapor phase (3510.05 mg g-1). It can be ascribed to the fully interactions between the extensive accessible active sites on the largely exposed surface of 2D MOF nanosheets and the target pollutants, which also gave rise to fast adsorption kinetics with relative high removal efficiencies in the low concentrations, even in seawater. Moreover, a facile recyclability with fast desorption kinetics can also be achieved for the MOF nanosheets. The excellent iodine removal performance in aqueous solution demonstrated that the electrostatic attraction between MOF nanosheets with a positive charge and the negatively charged triiodide (I3-, the dominant form of iodine in aqueous solution) is the driving force in adsorption, which endows the adsorbents with the characteristics of fast adsorption and desorption kinetics. The adsorption mechanism was systematically verified by the studies of ζ potential, Fourier transform infrared, X-ray photoelectron spectroscopy, and Raman spectra.

GSA-Human: Genome Sequence Archive for Human.

The Genome Sequence Archive for Human (GSA-Human) is a data repository specialized for human genetic related data derived from biomedical researches, and also supports the data collection and management of National Key Research and Development Projects. GSA-Human has a data security management strategy according to the national regulations of human genetic resources. It provides two different models of data access: Open-access and Controlled-access. Open-access data are universally and freely accessible for global researchers, while Controlled-access ensures that data are accessed only by authorized users with the permission of the Data Access Committee (DAC). Till July 2021, GSA-Human has housed more than 5.27 PB of data from 750 datasets.

A cross-sectional study for estimation of associations between education level and osteoporosis in a Chinese men sample.

BACKGROUND: The main aim of this study was to evaluate the association between education level and osteoporosis (OP) in general Chinese Men. METHODS: We conducted a large-scale, community-based, cross-sectional study to investigate the association by using self-report questionnaire to assess education levels. The data of 1092 men were available for analysis in this study. Multiple regression models controlling for confounding factors to include education level were performed to explore the relationship between education level and OP. RESULTS: Positive correlations between education level and T-score of quantitative bone ultrasound (QUS-T score) were reported (ß = 0.108, P value < 0.001). Multiple regression analysis indicated that the education level was independently and significantly associated with OP (P < 0.1 for all models). The men with lower education level had a higher prevalence of OP. CONCLUSION: The education level was independently and significantly associated with OP. The prevalence of OP was more frequent in Chinese men with lower education level. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02451397 ; date of registration: 05/28/2015).

Efficient and selective removal of Pb2+ from aqueous solution by using an O- functionalized metal-organic framework.

Lead (Pb) is one of the most widespread and highly toxic heavy metals in the environment. The design and synthesis of adsorbent materials for the selective and efficient removal of Pb2+ from aqueous solution has received much attention. Herein, the ligand 4,4'-azoxydibenzoic acid with the O- group was elaborately selected to construct a novel Pr-based MOF for Pb2+ removal. The as-prepared MOF adsorbents with high stability exhibited ultra-high selectivity for Pb2+, even in the presence of various highly concentrated competitive ions (with the ratios from 1 : 5 to 1 : 50). Also, a high uptake capacity (560.26 mg g-1) can be achieved for the MOF material, due to the availability of sufficient adsorption sites. The strong electrostatic attraction and coordination interaction between the numerous active O- sites on MOF adsorbents and Pb2+ can account for the good adsorption performance for Pb2+, which was systematically verified by zeta potential, FT-IR and XPS studies.

Effective Removal of Chromium(III) from Low Concentration Aqueous Solution Using a Novel Diazene/Methoxy-Laced Coordination Polymer.

In this study, a novel coordination polymer [CdL2(H2O)0.5]n (1), [HL = 4-(2-(4-((pyridin-3-yl)methoxy)phenyl)diazenyl)benzoic acid] was fabricated via an in situ ligand transformation reaction under solvothermal conditions. The as-prepared polymer exhibited a selectivity and efficiency for Cr(III) removal with a high uptake capacity of 106.13 mg·g-1. Interestingly, even in the low concentration (0.02⁻0.20 ppm), it still performs a relatively high efficiency (≥ 92.5%) towards the removal of Cr(III) in aqueous solution. Remarkably, it also presents good selectivity and high efficiency (93.3%) for Cr(III) removal in the presences of interfering metal ions. The good removal performance for Cr(III) was demonstrated to be a structure-dependent chemical process between polymer and Cr(III) involving the diazene and methoxy groups in polymer 1, which happened not only on the surfaces of the adsorbent but also in the pores of polymer, giving rise to a strong affinity toward Cr(III) adsorption. The possible adsorption mechanism of Cr(III) was proposed and systematically verified by FT-IR, scanning electron microscope (SEM), atomic force microscope (AFM) and energy dispersive spectrometer (EDS) measurements.

Development of a monoclonal antibody-based enzyme-linked immunosorbent assay for the herbicide chlorimuron-ethyl.

Hybridomas secreting a monoclonal antibody (mAb) against the herbicide chlorimuron-ethyl (CE) were produced by fusing the mouse myeloma cell line (SP2/0) with splenocytes from a mouse immunized against the conjugate of the sulfonamide moiety of CE and bovine serum albumin (BSA). The mAb, designated 1F5C5A10, had very weak affinity with metsulfuron, ethametsulfuron, pyrazosulfuron, bensulfuron, and chlorsulfuron. Two mAb-based indirect competitive enzyme-linked immunosorbent assays (icELISA) were developed. A conventional icELISA (icELISA-I) showed a concentration of half-maximum inhibition (IC(50)) of 11.6 ng/mL with a dynamic range of 1.6-84 ng/mL. A simplified icELISA (icELISA-II) had an IC(50) of 28.7 ng/mL and a dynamic range of 2.2-372 ng/mL. The two assays were tested on spiked water and soil samples. CE (1-500 ng/mL) fortified in water samples could be analyzed directly without any sample preparation by both immunoassays with an average recovery between 74 and 114%. icELISA-II, but not icELISA-I, was able to accurately analyze the herbicide residues in the crude soil extracts with recoveries between 99 and 129% without obvious matrix effects due to its lesser amount of sample used. In contrast to icELISA-I, icELISA-II is more convenient, whereas it consumes more reagents of coating antigen and goat anti-mouse IgG-peroxidase.

Construction of Four Zn(II) Coordination Polymers Used as Catalysts for the Photodegradation of Organic Dyes in Water.

Hydrothermal reactions of Zn(OAc)2·2H2O with flexible bipyridyl benzene ligand and three dicarboxylic derivatives gave rise to four new coordination polymers, [Zn7(µ4-O)2(OAc)10(bpmb)]n (1), [Zn(5-OH-1,3-BDC)(bpmb)]n (2), [Zn(1,2-BDC)(bpmb)]n (3) and [Zn2(ADB)2(bpmb)]n (4) (bpmb = 1,4-bis(pyridine-3-ylmethoxy)benzene, 5-OH-1,3-H2BDC = 5-hydroxy-1,3-benzenedicarboxylic acid, 1,2-H2BDC = 1,2-benzenedicarboxylic acid, H2ADB = 2,2'-azodibenzoic acid). Their structures were characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Compound 1 features a one-dimensional (1D) chain structure based on the rare heptanuclear [Zn7(µ4-O)(µ3-OAc)2(µ2-OAc)8] units. Compound 2 exhibits a novel 2D bilayer structure built from the two parallel 2D (4,4) layers. Compound 3 holds a 2D structure in which the 1,2-BDC ligands work as lockers interlocking 1D [Zn(bpmb)]n chain. Compound 4 comprises a 3D framework constructed by 2D wrinkled [Zn2(ADB)4]n networks and bpmb linkers with a six-connected pcu net. These results suggest that the motifs of the dicarboxylic ligands have significant effect on the final structures. These compounds exhibited relatively good photocatalytic activity towards the degradation of methylene blue (MB) in aqueous solution under a Xe lamp irradiation.

The crystal structure and photocatalytic properties of a three-dimensional cadmium(II) metal-organic framework: poly[bis(µ3-benzene-1,2-dicarboxylato)[µ2-1,4-bis(pyridin-3-ylmethoxy)benzene]dicadmium(II)].

Photocatalysis is a green technology for the treatment of all kinds of contaminants and has advantages over other treatment methods. Recently, much effort has been devoted to developing new photocatalytic materials based on metal-organic frameworks for use in the degradation of many kinds of organic contaminants. With the aim of searching for more effective photocatalysts, the title three-dimensional coordination polymer, [Cd2(C8H4O4)2(C18H16N2O2)]n, was prepared. The asymmetric unit contains one Cd(II) cation, one benzene-1,2-dicarboxylate anion (denoted L(2-)) and half of a centrosymmetric 1,4-bis(pyridin-3-ylmethoxy)benzene ligand (denoted bpmb). Each Cd(II) centre is five-coordinated by four carboxylate O atoms from two L(2-) ligands and by one N atom from a bpmb ligand, forming a disordered pentagonal pyramidal coordination geometry. The Cd(II) centres are interlinked by L(2-) ligands to form a one-dimensional [Cd2L2]n chain. Adjacent chains are further connected by bpmb linkers, giving rise to a two-dimensional network, and these networks are pillared by bpmb to afford a three-dimensional framework with a 3(3).4(2).6(3).7(1).8(1) topology. Each grid in the framework has large channels which are filled mainly by the two other equivalent frameworks to form a threefold interpenetrating net. The compound exhibits relatively good photocatalytic activity towards the degradation of methylene blue in aqueous solution under UV irradiation.

Construction of five Zn(ii)/Cd(ii) coordination polymers derived from a new linear carboxylate/pyridyl ligand: design, synthesis, and photocatalytic properties.

Solvothermal reactions of Cd(OAc)2/Zn(OAc)2 with a new ligand, (pyridin-3-yl)methyl 4-(2-(4-((pyridin-3-yl)methoxy)phenyl)diazenyl)benzoate (L1), under different templates via an in situ ligand transformation reaction produced five coordination polymers, [CdL2(H2O)]n (1), [Cd1.5L3]n (2), [Cd2L4]n (3), [(ZnL2)·H2O]n (4) and {[Zn(1,3-BDC)(L1)]·MeCN·0.5H2O}n (5), where HL = 4-(2-(4-((pyridin-3-yl)methoxy)phenyl)diazenyl)benzoic acid, 1,3-H2BDC = 1,3-benzenedicarboxylic acid. Compound 1 is a three-dimensional (3D) wave-like structure constructed from 4-connected Cd(ii) nodes and L(-) linkers. Compounds 2 and 3 bear similar 2D networks built from metallocyclic [Cd4L4] units. Compound 4 features a wrinkled 2D layer based on metallocyclic [Zn4L4] units. Compound 5 has a novel 1D single-wall metal-organic nanotube (SWMONT) in which the 1,3-BDC ligands act as linkers to connect the [Zn2(L1)2] rings. The results reveal that the different templates have a significant effect on the final structures. Compounds 1-5 exhibited relatively high photocatalytic activity towards the degradation of methylene blue (MB) in aqueous solution under UV-Vis irradiation. The kinetics of the catalytic photodegradation reactions and the stabilities of photocatalysts were also investigated.

A novel Ag(i)-calix[4]arene coordination polymer for the sensitive detection and efficient photodegradation of nitrobenzene in aqueous solution.

Nitrobenzene (NB) is a widespread and highly toxic organic pollutant in water, and consequently its detection and removal have attracted considerable attention. In the present study, we designed and synthesized a novel coordination polymer, [AgL0.5(NO3)]n (1), {L = 25,26,27,28-tetra[(3-pyridylmethyl)oxy]calix[4]arene}, from AgNO3 and a tetra-pyridyl-functionalized calix[4]arene ligand, which possessed a 2D network based on [Ag4L(NO3)4] units. The 1-modified glassy carbon electrode (1/GCE) exhibited good electrocatalytic activity toward the reduction of NB, offering the selective detection of NB in a wide linear range (1-2450 µM) and a low detection limit (0.62 µM). Furthermore, it displayed excellent photocatalytic activity for the degradation of NB in aqueous solution under UV light. The kinetics of the catalytic degradation reaction and the stability of the catalyst were also studied. These results indicated that compound 1 is a favorable material for the effective determination and degradation of NB, which makes it a promising candidate in both monitoring water quality and treating wastewater.

[Level indicators construction and temporal-spatial distribution features of agricultural flood in the southwest of China].

Flood level indicators of southwest provinces were built in this study by using daily precipitation data of 341 weather stations in southwest agricultural areas from 1961 to 2010 combined with grey correlation analysis. In the process of building the indicators, we took single station flood indicators of Chongqing as the prototype. Through increasing and decreasing the precipitation threshold of Chongqing indicators by the amplitude of -50-+50 mm and the step size of 1 mm, each province got 101 groups of flood indicators. Based on the correlation between flood intensity calculated by all the indicators and crop flood real seriousness, coincidence between indicators and historical flood records and the comparability of different province indicators, we finally constructed agricultural flood level indicators of each province step by step. According to the flood indicators, we also analyzed temporal-spatial distribution features of flood disaster in southwest agricultural areas. The results were as follows: the final indicators of Yunnan were the original indicators plus 16 mm, while it was plus 30 mm for Guizhou and plus 40 mm for Sichuan-Chongqing. The correlation coefficients between flood index defined by indicators and affected ratio were 0.314 (P < 0.05), 0.553 (P < 0.01) and 0.305 (P < 0.05), respectively. The coincidence was relatively high between indicators and historical flood records. The ages in which flood disaster appeared very serious were 1980s in Yunnan, 1990s in Guizhou and 1980s and 2000s in Sichuan-Chongqing in the nearly 50 years. In the southwest and southeast of Yunnan, southwest of Guizhou and west and northeast of Sichuan Basin, the flood disaster was prevalent.

Structural diversity and photocatalytic properties of Cd(II) coordination polymers constructed by a flexible V-shaped bipyridyl benzene ligand and dicarboxylate derivatives.

Hydrothermal reactions of Cd(OAc)2·2H2O with a flexible V-shaped bipyridyl benzene ligand and five benzenedicarboxylic acid derivatives gave rise to five new coordination polymers i.e., [Cd(1,4-BDC)(bpmb)(H2O)]n (1), {[Cd(1,3-BDC)(bpmb)]·0.125H2O}n (2), [Cd2(5-Me-1,3-BDC)2(bpmb)2]n (3), [Cd(5-NO2-1,3-BDC)(bpmb)(H2O)]n (4) and [Cd(5-OH-1,3-BDC)(bpmb)(H2O)]n (5) (bpmb = 1,3-bis(pyridine-3-ylmethoxy)benzene, 1,4-H2BDC = 1,4-benzenedicarboxylic acid, 1,3-H2BDC = 1,3-benzenedicarboxylic acid, 5-Me-1,3-H2BDC = 5-methyl-1,3-benzenedicarboxylic acid, 5-NO2-1,3-H2BDC = 5-nitro-1,3-benzenedicarboxylic acid, 5-OH-1,3-H2BDC = 5-hydroxy-1,3-benzenedicarboxylic acid). Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Compound 1 is a two-fold interpenetrating network showing the coexistence of polyrotaxane and polycatenane characters. Compounds 2 and 3 exhibit similar 2D (3,5)-connected (4(2)·6(7)·8)(4(2)·6) nets in which the bpmb ligands work as lockers in interlocking 1D [Cd(1,3-BDC/5-Me-1,3-BDC)]n chains. Compound 4 shows a 2D 4-connected (6(6)) sandwich-like structure with differently oriented [Cd(5-NO2-1,3-BDC)]n chains. Compound 5 is a 3D supramolecular pcu net based on a 1D ladder-shaped chain. These results suggest that the substituted positions of carboxylate groups and changes in substituted R groups in the 5-position of BDC ligands have significant effect on the final structures. These compounds exhibited relatively good photocatalytic activity towards the degradation of methylene blue (MB) in aqueous solution under UV irradiation. Moreover, solid-state photoluminescence properties of 1-5 were also investigated.

Calcium phosphate nanoparticles are associated with inorganic phosphate-induced osteogenic differentiation of rat bone marrow stromal cells.

In the present study, we demonstrated that calcium phosphate (CaP) nanoparticles formed in cell culture media were implicated in the process of high inorganic phosphate (Pi) mediated osteogenic differentiation of rat bone marrow stromal cells (BMSCs). Exposure of BMSCs in vitro to high Pi-containing media reduced alkaline phosphatase (ALP) activity and the expressions of osteoblast-specific genes. The sediments of CaP nanoparticles were observed at the cell surface and some of them were concomitantly found inside cells at high Pi concentration. In addition, treatment the cells with pyrophosphate (PPi), an inhibitor of calcium crystal formation, abrogated the ALP activity induced by high Pi, suggesting the contribution of CaP nanoparticles. Moreover, for isolated CaP nanoparticles, there was a trend of conversion from amorphous calcium phosphate to hydroxyapatite with elevated Pi. The particle size of CaP increased and the surface morphology changed from spherical to irregular due to increased concentrations of serum proteins incorporated into CaP nanoparticles. The study demonstrated that those physicochemical properties of CaP nanoparticles played an important role in modulating BMSCs differentiation. Furthermore, the addition of Pi in the osteogenic media resulted in a dose-dependent increase in matrix mineralization, while treatment of the cells with PPi suppressed Pi-induced calcium deposition. The findings indicated that calcium deposition in the matrix partly came from the spontaneous precipitation of CaP nanoparticles.

A three-dimensional Pb(II) coordination framework: poly[[µ4-(E)-2,2'-(diazene-1,2-diyl)dibenzoato]dimethanollead(II)].

In the title coordination polymer, [Pb(C14H8N2O4)(CH3OH)2]n, the asymmetric unit contains half of a Pb(II) cation, half of a 2,2'-(diazene-1,2-diyl)dibenzoate dianionic ligand (denoted L(2-)) and one methanol ligand. Each Pb(II) centre is eight-coordinated by six O atoms of chelating/bridging carboxylate groups from four L(2-) ligands and two O atoms from two terminal methanol ligands, forming a distorted dodecahedron. The [PbL2(MeOH)2] subunits are interlinked via the sharing of two carboxylate O atoms to form a one-dimensional [PbL2(MeOH)2]n chain. Adjacent chains are further connected by L(2-) ligands, giving rise to a two-dimensional layer, and these layers are bridged by L(2-) linkers to afford a three-dimensional framework with a 4(12)6(3) topology.

A helical zinc(II) coordination polymer assembled from 1,3-bis[(pyridin-3-yl)methoxy]benzene and benzene-1,4-dicarboxylic acid.

In catena-poly[[aqua[1,3-bis(pyridine-3-ylmethoxy)benzene-κN]zinc(II)]-µ2-benzene-1,4-dicarboxylato-κ(2)O(1):O(4)], [Zn(C8H4O4)(C18H16N2O2)(H2O)]n, each Zn(II) centre is tetrahedrally coordinated by two O atoms of bridging carboxylate groups from two benzene-1,4-dicarboxylate anions (denoted L(2-)), one O atom from a water molecule and one N atom from a 1,3-bis[(pyridin-3-yl)methoxy]benzene ligand (denoted bpmb). (Aqua)O-H···N hydrogen-bonding interactions induce the formation of one-dimensional helical [Zn(L)(bpmb)(H2O)]n chains which are interlinked through (aqua)O-H···O hydrogen-bonding interactions, producing two-dimensional corrugated sheets.

A three-dimensional Zn(II) coordination framework: poly[[µ2-(E)-1,2-bis(pyridin-4-yl)ethene][µ4-(E)-2,2'-(diazene-1,2-diyl)dibenzoato][µ2-(E)-2,2'-(diazene-1,2-diyl)dibenzoato]dizinc(II)].

In the title coordination polymer, [Zn2(C14H8N2O4)2(C12H10N2)]n, the asymmetric unit contains one Zn(II) cation, two halves of 2,2'-(diazene-1,2-diyl)dibenzoate anions (denoted L(2-)) and half of a 1,2-bis(pyridin-4-yl)ethene ligand (denoted bpe). The three ligands lie across crystallographic inversion centres. Each Zn(II) centre is four-coordinated by three O atoms of bridging carboxylate groups from three L(2-) ligands and by one N atom from a bpe ligand, forming a tetrahedral coordination geometry. Two Zn(II) atoms are bridged by two carboxylate groups of L(2-) ligands, generating a [Zn2(CO2)2] ring. Each loop serves as a fourfold node, which links its four equivalent nodes via the sharing of four L(2-) ligands to form a two-dimensional [Zn2L4]n net. These nets are separated by bpe ligands acting as spacers, producing a three-dimensional framework with a 4(6)6(4) topology. Powder X-ray diffraction and solid-state photoluminescence were also measured.

Three coordination polymers constructed from various polynuclear clusters spaced by 2,2'-azodibenzoic acid: syntheses and fluorescent properties.

Solvothermal reactions of M(OAc)2·2H2O (M = Zn, Cd, Pb) with 2,2'-azodibenzoic acid (H2L) in MeOH-H2O (MeOH = methanol) at 120 °C gave rise to three coordination polymers, [Zn12(µ4-O)3L9]n (1), [CdL(H2O)]n (2) and [Pb3(µ4-O)L2]n (3). Compounds 1-3 are characterized by elemental analysis, IR, powder X-ray diffraction and single-crystal X-ray diffraction. Compound 1 has two similar tetranuclear [Zn4(µ4-O)(µ2-CO2)6] units as nodes and displays an intriguing three-dimensional (3D) 6-connected network with a 4(12)6(3) topology. Compound 2 exhibits a 3D framework constructed by linking infinite helical Cd-carboxylate chains through L ligands. Compound 3 holds a 3D structure in which each hexanuclear [Pb6(µ4-O)2(CO2)4] unit works as a six-connecting node to connect its equivalent ones via sharing L ligands. In addition, the fluorescent properties and thermal stabilities of 1-3 were also investigated.