Connected 3D Framework Research Articles

Five new luminescent Pb(II) and Ag(I) coordination polymers based on 1-(4-carboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid and different neutral ligands

Five new coordination polymers (CPs), namely {Pb1.5(L)} (1), {Pb3(L)2(2,2′-bpy)·2·5H2O} (2), {[Pb(HL)(phen)]·H2O} (3), {Ag2(HL)} (4) and {Ag(H2L)(phen)} (5), have been constructed by using 1-(4-carboxybenzyl)-1H-pyrazole-3,5-dicarboxylic acid (H3L) as an organic ligand. Compound 1 reveals a three-dimensional (3D) (4,6,7)-connected framework with the point symbol of {410·65}{46}2{48·613}2. Compound 2 exhibits a novel (3,6)-connected 3D framework based on a trinuclear Pb(II) cluster with point symbol {42.6}2{44.62.88.10}. Compound 3 is a 1D chain that is further assembled into a 3D supramolecular framework by hydrogen-bonds. Compound 4 shows a (3,6)-connected 3D structure based on a tetranuclear Ag(I) cluster with {4·62}2{42·610·83} topology. Compound 5 is a 0D structure, and can be further expanded into a 3D supramolecular network by various weak interactions. The solid-state luminescent spectra have been measured at room temperature. The results show that compounds 1–5 exhibit strong luminescent emission in the visible region, and can be tunable by varying excitation wavelengths.

Luminescence Cd(II) coordination compounds based on a semi-rigid tricarboxylic acid ligand for identifying metal cations, inorganic anions and organic solvents

Highly effective recognition and detection of metal ions, anions and organic small molecules from water have attracted remarkable attention for environmental safety. Herein, a novel Cd-based coordination polymer [Cd(HL)(4,4′-bipy)(H2O)]n (1) and a metal–organic framework {[Cd3(L)2(bip)2(H2O)3]·5H2O}n (2) have been synthesized by employing a semi-rigid tricarboxylic acid ligand (H3L) and different N-containing ligands under hydrothermal conditions, where H3L = 3-[(1-carboxynaphthalen-2-yl)oxy] phthalic acid, 4,4′-bipy = 4,4′-bipyridine, bip = 1,4-di(pyridine-4-yl) benzene. Single crystal X-ray analysis reveals that 1 presents a 4-connected 2D network structure with a Schläfli symbol of (44·62),whilst 2 possesses a (3,4,4)-connected 3D framework with a Schläfli symbol of (4.82)2(42.82.102)(8.104.12). Furthermore, 1 and 2 have been characterized by elemental analyses, FT-IR, powder X-ray diffraction, thermogravimetric analyses, fluorescence and UV spectra, exhibiting good stability and excellent photoluminescence properties. 1 and 2 have been chosen as fluorescent probes to sense different target analytes, showing an obvious selective recognition response to Co2+, Ag+, Cr2O72-, CrO42-, nitrobenzene and nitromethane through luminescence quenching effects in aqueous solutions. The possible fluorescence quenching mechanisms are studied in detail, revealing that fluorescence quenching is mainly related to weak interactions, competitive energy absorption and electron transfer.

Solvent-controlled metal coordination polymers of Co(ii) with different topological structures and properties

Three multidimensional Co-polymers were obtained. Co-1 exhibits as a 2D layer. Co-2 displays as a tetranodal (4,4,5,6)-connected 3D MOFs. Co-3 is a binodal (4,6)-connected 3D framework.

Rational design of three bifunctional MOFs for photocatalysis degradation and selective adsorption of wastewater organic dyes removal

Three metal–organic frameworks (MOFs) based on transition metals, namely{[Cd(HL)(tib)(H2O)]·1·.5H2O}}n (1), {[Co3(L)2(tib)2]·4H2O}n (2), [Cu(L)(3,5-bibp)]n (3) (H3L = 4-(3,5-dicarboxylatobenzyloxy)benzoic, tib = 1,3,5-tris(1-imidazolyl)benzene and 4,4′-bibp = 4,4′-bis(imidazol-1-yl)biphenyl) have been designed and successfully synthesized under solvothermal conditions. These three compounds were characterized by single crystal X-ray diffraction, elemental analysis, IR spectra, powder X-ray diffraction (PXRD), thermogravimetric analysis(TGA) and electrochemical studies. Single crystal X-ray diffraction analysis reveals that compound 1 possesses a 2-nodal (3,5)-connected hms topology framework with the point symbol (63·69.8), compound 2 unprecedented 3-nodal (8,8,11)-connected 3D framework with a (37·412·59) (38·413·57) (39·419·523·64) topology, while compound 3 displays a 3D 4-connected sql topology. The electrochemical studies for compound 2 and 3 have been discussed. Photocatalytic degradation and adsorption for organic dyes removal from wastewater using three compounds have been investigated. Significantly, all of the three compounds show good photocatalytic activities for MB and selective adsorption capacity for CR.

Highly selective, sensitive and stable three-dimensional luminescent metal–organic framework for detecting and removing of the antibiotic in aqueous solution

An efficiently selective sensor for aquatic antibiotic detection based on a photoluminescent cadmium metal–organic framework (Cd-MOF) is researched in this work. The novel and simple luminescent MOF that composed from a π-electron rich ligand bip (3,5-bis(1-imidazol) pyridine) and H3L (2-nitro-5-(4-carboxy-2-nitrophenoxy) isophthalic) was synthesized in hydrothermal condition and characterized. Single crystal X-ray diffraction analysis demonstrated that it had an uncommon 2-nodal (3,6)-connected 3D framework with a (32·4)(34·46·53·62) topology, which could be formulated as [{[Cd2(HL)2(bip)2]·H2O}n]. Benefiting from its unique framework, [{[Cd2(HL)2(bip)2]·H2O}n] can not only respond to the trace quantity of chloramphenicol (CHL) via fluorescence quenching but also show good adsorption capability toward CHL in aqueous solution. The selective response to CHL reached up to the ppb level with high anti-interference ability in aqueous phase, and the effective detection of antibiotics had been theorized by Density Functional Theory (DFT) calculation for energy bands of H3L and antibiotics, which revealed that the cooperation influence on photo-induced electron transfer (PET) process and fluorescence inner filter effect (IFE) made CHL show more sensitive luminescence responses than other experimental antibiotics. Moreover, because of its specific interactions with analytes and relatively high porosity, the pre-enrichment makes the antibiotic fuller contact and interact with the framework, which improves the overall sensing efficiency towards CHL appreciably. Stemming from the abuse, antibiotics have been considered as the great threat to the health of human race and the sustainable development of society. Therefore, it is extremely important to achieve new technology to detect and absorb antibiotics residues in water. This work proves that metal–organic framework complexes can conform the performance of detecting and removing antibiotic in aqueous environment, that emphasizes the application of luminescent MOFs in contaminant monitoring and removing.

AIE ligands-based new cobalt metal-organic framework as bifunctional sensor for Fe3+ ion and TNP in aqueous solution

A novel MOF, namely, {Co(TCPP)0.5(Tipa)}n (1) based on the mixed ligands 2, 3, 5, 6-tetrakis(4-carboxyphenyl)pyrazine (H4TCPP) and tri(4-imidazolylphenyl)amine (Tipa) has been successfully constructed by assembling two aggregation-induced emission (AIE) ligands with cobalt nitrate under hydrothermal condition. Crystal structure analysis indicates 1 displays a (3,4,5)-connected 3D framework, with a new Schläfli symbol of {42·6}2{42·84}{43·6·86}2. Fluorescence measurement shows 1 exhibits more bright fluorescent emission in water compared with that in other solvents. Meanwhile, it shows fluorescence stability in water with different pH values ranging from 3.0 to 11.0. More significantly, compound 1 could be employed as bifunctional sensor for ferric ion (Fe3+) and picric acid (TNP) in aqueous solution with high selectivity, high sensitivity and well cyclic utilization, and the detection limits for Fe3+ and TNP are estimated to be 0.098 ​μM and 0.326 ​μM, respectively.

The effects of the coordination orientation and steric hindrance of ligands on the structural diversity of Pb(II) coordination polymers

Five new lead(II) coordination polymers, [Pb(L)]n (1), [Pb3(L)3]n·4nH2O (2), [Pb2(L)(1,2-bdc)]n·nH2O (3), [Pb2(L)(1,3-bdc)]n·nH2O (4) and [Pb4(L)2(1,4-bdc)2(H2O)2]n·2nH2O (5) (H2L = 4′-(4-carboxyphenyl)-6′-carboxycalte-2,2′-bipyridine, H2(1,2-bdc) = benzene-1,2-dicarboxylic acid, H2(1,3-bdc) = benzene-1,3-dicarboxylic acid and H2(1,4-bdc) = benzene-1,4-dicarboxylic acid) were prepared under hydrothermal conditions. Compound 1 shows a 2D ladder single-layer with the hcb topology. Compound 2 presents a 2D ladder double-layer, which shows a 3-connected hcb topology. Compound 3 exhibits a 1D loop chain based on [Pb4(COO)6] tetranuclear units. Compound 4 displays a (3,4)-connected 3D framework with 3,4T10 topology consisting of [Pb2O2] units. Compound 5 exhibits a self-penetrating 3D network based on [Pb4(COO)2] units, which features an intriguing new topological net. The structural diversity of 1–5 gives some insights that the pH value and coordination orientations of aromatic dicarboxylates play significant roles in construction of coordination polymers. Meanwhile, the hemi-directed or holo-directed coordination geometries depend on coordination numbers of Pb(II) ions. Furthermore, tetrel bonds enhance the structural stability of these Pb(II) coordination polymers.

Polynuclear Cd(II) coordination polymer with unique configuration for chromium pollutants removal

To systematically explore the effects of polynuclear complexes on the removal of chromium pollutants, a new three-dimensional (3D) microporous metal-organic compound [Cd3(HCO2)2(dpa)4(bpp)3]n (dpa ​= ​diphenic acid, bpp ​= ​1,3-bi(4-pyridyl)propane) (1) was prepared through hydrothermal synthesis. The structure was characterized by X-ray single crystal diffraction, elemental analysis, and Fourier transform infrared spectroscopy. The results indicate that complex 1 based on Cd(II) clusters is monoclinic and consists of the C2/c space group. It exhibits a new 2-nodal (3,5)-connected 3D framework with a Schläfli symbol of {43}{45, 65}. The thermogravimetric analysis (TGA) reveals complex 1 has high thermal stability (stable until 490 ​°C). The photoluminescence shows the emission wavelength of the fluorescence is red-shifted (30 ​nm), and the intensity is significantly increased compared to the free ligand. Adsorption analysis shows that the Cd(II) compound demonstrates significant adsorption towards the dichromate anion (Cr2O72−). Its adsorption isotherm is consistent with the Langmuir model and its adsorption kinetics follows a pseudo-second-order model.

Two novel 3D MOFs based on the biphenyl-2,4,6,3′,5′-pentacarboxylic acid ligand: Synthesis, crystal structure and luminescence properties

Two novel 3D metal-organic frameworks [Cd3 (bpbc)(μ3-OH)(H2O)3]·H2O (1) and [Zn2Na (bpbc)(DMF)1.5 (EtOH)0.5 (H2O)5]·0.5H2O (2) have been synthesized by using biphenyl-2, 4, 6, 3′, 5′-pentacarboxylic acid (H5bpbc) as the ligand under solvothermal/hydrothermal conditions. The complexes were characterized by elemental analysis, single-crystal X-ray diffraction (XRD), powder X-ray diffraction (PXRD), IR spectra and thermogravimetric analysis (TGA). Structural analysis revealed that complex 1 shows a (5, 10)-connected 3D network based on the [Cd6 (COO)10(μ3-OH)2] SBUs with unusual topology, while complex 2 exhibits a (3, 3, 6)-connected 3D framework. The structural difference between 1 and 2 indicated that the coordination fashion of bpbc5− and the kind of metal ions could play critical role in the construction of MOFs. In addition, new fluorescence emissions were observed for 1 and 2, and the solid state luminescent properties were investigated.

RETRACTED: Temperature induced two new trinuclear Co(II) cluster-based compounds: Luminescent, photocatalytic and anti-breast cancer properties

Abstract Two new trinuclear Co(II) cluster-based compounds, namely [Co3(L)2(H2O)4]n (1) and [Co1.5(L)(H2O)2]n (2) (H3L = biphenyl-3,4’,5-tricarboxylic acid), have been synthesized under hydrothermal conditions via tuning reaction temperature. Single crystal X-ray diffraction analyses revealed that both compound 1 and 2 contain trinuclear Co(II) cluster subunits: trinuclear [Co3(COO)4(H2O)2] cluster for 1 and trinuclear [Co3(COO)6] cluster for 2. Due to the different coordination modes of L3− ligand, compound 1 features a (3,6)-connected 3D framework with a rtl-type topology, and compound 2 features a (3,6)-connected 3D framework with a new topology which has not been reported in the TOPOS and RCSR database. The thermal stabilities and luminescent properties for the two compounds have been investigated. The photophysical properties studies showed that compounds 1 and 2 are excellent candidiates as potential semiconductive materials. Moreover, compounds 1 and 2 exhibit high photocatalytic efficiency for the degradation of methylene blue (MB) under UV light irradiation. In addition, the cytotoxicity of complexes 1 and 2 has been evaluated against three human breast cancer cells (MCF-7, MDA-MB-231 and BT-549) via the MTT assay.

Effective luminescence sensing of Fe3+, Cr2O72-, MnO4- and 4-nitrophenol by lanthanide metal-organic frameworks with a new topology type.

Lanthanide MOFs (Ln-MOFs), {[Ln2(L)2(H2O)2]·5H2O·6DMAC}n, [Ln||| = Eu(1) and Tb(2); H3L = 4,4'-(((5-carboxy-1,3-phenylene)bis(azanediyl))bis(carbonyl)) dibenzoic acid, DMAC = N,N'-dimethylacetamide], with a new topology type have been isolated. Single crystal X-ray diffraction indicates that complexes 1 and 2 are isostructural with binuclear [Eu2(COO)7]n secondary building units as 7-connected nodes and H3L ligands as 3-connected nodes and can be viewed as a (5,7)-connected 3D framework with a new topological point symbol of {32·44·54} {34·46·56·65}. Complexes 1 and 2 exhibit an excellent luminescence sensing response to inorganic ions Fe3+, Cr2O72-, MnO4- and 4-nitrophenol, with a low detection limit and high Ksv value. Interestingly, when the MnO4- ions are detected, the color of the solid sample is observed to change from yellow to brown, visually indicating luminescence induction, which makes the process of detecting MnO4- ions simpler and more practical. Moreover, by using time-resolved photoluminescence techniques, complex 1 can effectively eliminate background fluorescence interference during detection and improve detection accuracy. Solvent luminescence studies, pH stability and PXRD data indicate that complexes 1 and 2 can be used as excellent water-stable multi-response luminescent sensors for detecting a wide variety of toxic substances. In addition, the mechanism of selective detection is explained by the energy competition between the excitation of complexes 1 and 2 and the ultraviolet absorption of the responsive substance.

Highly selective functional luminescent sensor toward Cr(VI)/Fe(III) ion and nitrobenzene based on metal–organic frameworks: Synthesis, structures, and properties

Six functional metal-organic frameworks constructed from semi-flexible 4,4′-bis(imidazolyl)diphenyl ether (bidpe), namely: [Zn(bidpe)(mpa)]n (1), [Cu(bidpe)(mpa)(H2O)]n (2), [Cd(bidpe)(mpa)]n (3), [Zn1.5(bidpe)2(smpa)(H2O)]n (4), [Cu1.5(bidpe)2(smpa)(H2O)]n (5), [Cd(bidpe)(hmpa)]n (6) (H2mpa = m-Phthalic acid, H2smpa = 5-sulfonatobenzene-1,3-dicarboxylate, H2hmpa = 5-Hydroxyisophthalic acid), have been synthesized under solvothermal conditions. Single-crystal X-ray diffraction analysis reveals that complexes 1–4 and 6 show 2D→3D supramolecular structure with a Schläfli symbol of (44·62), (4·65), (44·62), (42·6) and (63) topology, respectively. Complex 5 possesses an unprecedented (3, 4, 6)-connected 3D framework with a Schläfli symbol of (4·64·8)2(42·64·89)(62·8)2. Meanwhile, complexes 1, 3, 4 and 6 have excellent fluorescence properties and can be used as potential luminescent sensors for sensing Cr(VI) anions, Fe(III) ions and nitrobenzene (NB) with high selectivity and sensitivity. The photocatalytic studies indicate that 1 has good photocatalytic capability in degradation of methylene blue (MB), 1 and 6 have good photocatalytic capability in degradation of methyl violet (MV). Furthermore, the possible sensing mechanism and photocatalytic mechanism have been discussed.

Syntheses, structures and luminescent properties of Zn/Cd coordination polymers based on 4′-(2-carboxyphenyl)-3,2′:6′,3″-terpyridine

Six new Zn/Cd coordination polymers (CPs) based on a new terpyridine derivative ligand, namely, [ZnLCl]n·nH2O (1), [ZnL2]n (2), [CdL2(H2O)2]n (3), [CdL2(H2O)]n (4), [Cd2L2(m-bdc)(H2O)2]n (5), [Cd2L2(m-bdc)(H2O)]n (6), (H2(m-bdc) = benzene-1,3-dicarboxylic acid, HL = 4′-(2-carboxyphenyl)-3,2′:6′,3″-terpyridine), have been synthesized under hydrothermal conditions and characterized by elemental analyses, infrared spectra, single-crystal X-ray diffraction. Compound 1 displays a 3D utp topology based on left- and right-handed helical chains. Compounds 2, 3 and 4 are three kinds of 1D loop chain structures. Compound 5 features a (3,6)-connected 3D topology with point symbol of {42·6}2{44·62·88·10}. Compound 6 reveals a (3,6,8)-connected 3D framework with point symbol of {4·52}2{48·56·68·74·8·9}{48·66·7}. Luminescent properties of compounds 1–6 at room temperature were investigated.

Cu-containing Keggin-type polyoxometalates-based organic-inorganic hybrids with double electro-catalytic behaviors

Four new organic-inorganic hybrids consisting of Keggin-type polyoxometalates: [Cu5(bimpy)5(α-BW12O40)]·4H2O (1), [Cu4(bimpy)4(α-SiW12O40)]·2H2O (2), [Cu4(bimpy)4(α-HPMo12O40)2]·2H2O (3), [Cu2(bimpy)4(H2O)2(α-HPW12O40)2]·8H2O (4) (bimpy = 2,5-bis(1H-imidazol-1-yl)pyridine), have been hydrothermally synthesized. Compounds 1–4 are constructed from Cu/bimpy segments modified different types of Keggin POMs. The 1D double chains of compound 1 are featured by {-Cu/bimpy-POM-Cu/bimpy-}n chains and {-Cu-bimpy-Cu-}n metal-organic chains; compound 2 with 1D “ladder-like” structure stemmed from {-Cu-bimpy-Cu-}n wave-like chains and α-SiW12 clusters; In compound 3, [Cu4(bimpy)4]4+ motifs are linked by α-PMo12 clusters to give rise to a (3,4)-connected two-dimensional architecture with the (83)(86) topology, while compound 4 has a (3,4,5)-connected 3D framework with the (42,6)(42,6,83)(42,65,83) topology. Cyclic voltammetries of compounds 1–4 show discrepant double electro-catalytic properties for reduction of nitrite and oxidation of ascorbic acid owing to variant Keggin-type POMs and Cu/bimpy complexes.

Structural diversity of a series of terpyridyl carboxylate coordination polymers: Luminescent sensor and magnetic properties

Eleven new coordination polymers, [Zn2(ctpy)2(HCOO)2]n·3nH2O (1), [Zn2(ctpy)2(HCOO)2(H2O)2]n·nH2O (2), [Zn2(ctpy)2(H2O)4]n·2n(CH3COO)·nH2O (3), [Zn2(ctpy)2(CH3COO)2]n·nH2O (4), [Zn(ctpy)2]n·nH2O (5), [Zn2(ctpy)2(Hidc)(H2O)2]n(6), [Cd2(ctpy)4]n(7), [Cd2(ctpy)2(Hidc)]n(8), [Co2(ctpy)2(HCOO)2(H2O)2]n·nH2O (9), [Co(ctpy)(DMF)(ox)0.5]n(10), [Co(ctpy)(ox)0.5]n(11) and the closely related compound [Zn(ctpy)(ox)0.5]n·0.5nH2O (12) (Hctpy = 4′-carboxy-4,2′:6′,4′′-terpyridine, H2ox = oxalic acid and H3idc = imidazole-4,5-dicarboxylic acid) have been synthesized by hydro(solvo)thermal reaction of 4′-carboxy-4,2′:6′,4′′-terpyridine with divalent metal salts and characterized by elemental analysis, IR spectra, single crystal X-ray diffraction. Compounds 1 and 4 have similar structure which demonstrate a two-fold interpenetrating 3D framework with a 3-connected utp topological net, which contains the same number of left and right-handed 21 helical chains. Compounds 2 and 9 are isostructural 2D layer with a 3-connected hcb topological net. Similar to 2, compound 3 also displays a 3-connected 2D hcb topological net. Compounds 5 and 10 are a 2D layer with a 4-connected sql topological net. Compound 6 shows a chiral 2D layer based on a 1D left- or right-handed helical chains, which are further extended into an achiral 2D + 2D→3D supramolecular network by hydrogen bonds with alternately arrangement. Compound 7 features an unusual 2-fold interpenetrating 3D coordination network which exhibits a new intriguing (3,5)-connected binodal topological net with the Schläfli symbol of (52·6)(53·63·73·8). Compound 8 shows a 2D→3D supramolecular structure based on (3,4)-connected 2D bilayers with the Schläfli symbol of (44·62). Compound 11 displays an unusual three-dimensional coordination network which exhibits an intriguing (3,8)-connected binodal new topological net with Schläfli symbol (42·62)2(42·623·83). Compound 12 features a two-fold interpenetrating (3,4)-connected 3D framework with the fsc topological net. Compounds 1–12 were obtained under similar reaction conditions. The diverse structures indicate that rational selection of the second ligand, metal salt, counter anion and solvent are good methods to further design metal-organic compounds with new structures and properties. Moreover, their thermal stabilities, photoluminescent and magnetic properties were also investigated. More importantly, compound 12 has been successfully applied in the detection of Fe3+ ion in DMF solutions and nitrobenzene and the possible detecting mechanism was also discussed.

A Mn(II) coordination polymer from a polycarboxylate-containing ligand: synthesis, structural characterization, and properties

Abstract The neutral, four-fold protonated pyridine-3,5-dicarbox(3,5-dicarboxylatoanilide) (H4L) reacts with Mn(II) salts under hydrothermal conditions to yield a new complex: [Mn2(L)(H2O)2]·H2O (1), which has been characterized by single crystal X-ray diffraction, infrared spectroscopy, and elemental and thermogravimetric analyses. Complex 1 exhibits a binodal (4,8)-connected 3D framework with flu (412.612.84)(46)2 topology. The magnetic properties of 1 were investigated.

A new (4, 6)-connected Cu(I) coordination polymer based on rare tetranuclear [Cu4I2] clusters: Synthesis, crystal structure, luminescent and photocatalytic properties

A new Cu(I) coordination polymer, namely [Cu5I3(L)2]n (1 HL = 3-(4-pyridyl)-5-(3-pyridyl)-1,2,4-triazolyl), was solvothermally synthesized using CuI, HL and NaI as the starting materials. Single crystal X-ray structural analysis shows that compound 1 features a (4, 6)-connected 3D framework employing rare tetranuclear [Cu4I2] clusters as building subunits. It exhibits intense metal-to-ligand luminescence and excellent photocatalytic activity on degradation of methylene blue (MB).

Metal ion-tuned coordination polymers based on different isopolymolybdates grafted by in-situ ligand

By changing metal ions, three various transition metal coordination polymers based on different isopolymolybdates, [AgI(DTBA)(Mo2O6)] (1), [CuII3(DTBA)2(γ-Mo8O26)(H2O)6]·7H2O (2), and [CoII3(HDTBA)2(DTBA)2(γ-Mo8O26)(H2O)2]·6H2O (3) (HDTBA=3,5-di(1,2,4-triazol-1-yl) benzoic acid) have been synthesized and characterized. In compounds 1–3, the ligand 3,5-di-[1,2,4]triazol-1-yl-benzoic acid (HDTBA) was in-situ transformed from the 3,5-di-[1,2,4]triazol-1-yl-benzonitrile (DTCN) under hydrothermal conditions and two kinds of isopolymolybdates formed, both of which were directly grafted by the in-situ ligand DTBA. When Ag+ ion was presented, a 3D framework 1 is constructed from {[Mo4O13](DTBA)2} building blocks. Replacing Ag+ with Cu2+ ion, compound 2 shows a (2,4,8)-connected framework based on {(γ-Mo8O26)(DTBA)2} building units. A {(γ-Mo8O26)(DTBA)2} building unit-based (4,4,8)-connected 3D framework 3 is obtained in the presence of Co2+ ions. The metal atoms may play key roles in tuning the various structures of compounds 1–3, as well as the different isopolymolybdates. The electrochemical properties and photocatalytic activities of compounds 1–3 have been investigated here.

Syntheses, structural diversity and dye adsorption properties of various Co(II) coordination polymers based on rigid tris(imidazolyl) and dicarboxylate ligands

Three novel Co(II) coordination polymers, namely {[Co(tib)2]·2HNO3·2H2O}n (1), {[Co(tib)(4,4′-dpt)(H2O)2]·5H2O}n (2) and {[Co2(tib)2(1,3-dpb)2]·H2O}n (3) (tib=1,3,5-tris(1-imidazolyl)-benzene, 4,4′-dpt=p-terphenyl-4,4′-dicarboxylic and 1,3-dpb=1,3-di(4′-carboxyl-phenyl)benzene) were synthesized under solvo/hydrothermal conditions. These complexes were characterized by elemental analysis, IR spectra, powder X-ray diffraction (PXRD), thermogravimetric (TG) analysis and single-crystal X-ray diffraction. Complex 1 shows a rare kgd 2D-network compared with the normal (3,6)-connected networks (anh, ant, apo, brk, pyr, rtl), which is further assembled into a 3D architecture through H-bonds and C–H⋯O bonds. Complex 2 exhibits a hcb 2D-network, which is further assembled into a 3D supramolecular framework through hydrogen bonding interactions, while complex 3 shows an unprecedented 3-nodal (3,4,6)-connected 3D framework with the Schläfli symbol (62·7)2(64·75·84·9·10)(64·82). Interestingly, the whole structure of the tib-metallic complex 3 also shows an unprecedented 3D framework with (62·82·102)(62·8)2 topology, which is influenced by the “V”-shaped 1,3-dpb ligands in 3. Furthermore, dye adsorption studies indicate that complexes 1 and 2 can selectively adsorb MGO and GR, while complex 3 can selectively adsorb MO.

Nano-particle assembled porous core–shell ZnMn2O4 microspheres with superb performance for lithium batteries

Porous ZnMn2O4 microspheres were prepared via a facile co-precipitation method followed by calcination at various temperatures and evaluated as anode materials for lithium ion batteries. The sample prepared at 600 °C outperformed the other samples in terms of electrochemical performance with high reversible capacity, high-rate capability, and excellent cycling performance. The capacity of the sample remained as high as 999 mAh g−1 at a current rate of 100 mA g−1 after 50 cycles—one of the best ever reported for ZnMn2O4-based materials. A high reversible capacity of 400 mAh g−1 was retainable at a current density of 2000 mA g−1 after 2500 cycles. A novel electrochemical reaction mechanism of ZnMn2O4 anodes was established and investigated at length. The Mn3O4 observed during the charge process was largely responsible for the enhanced performance, as confirmed by x-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The relatively large surface area, abundant porosity, large ion exchange space, and strong mechanical stability of the porous connected 3D framework were responsible for the unique oxidation/reduction Mn2+ ↔ Mn3+ process we observed.