Sra Topology Research Articles

An amine decorated MOF for direct capture of CO2 from ambient air.

A Zn(II)-based metal-organic framework (MOF) was synthesized by the self-assembly of the dicarboxylate ligand terephthalic acid (TPA), 2-aminoterephthalic acid (NH2-TPA) and N-donor auxiliary ligand 1,4-bis(4-pyridinylmethyl)piperazine (bpmp) using Zn(NO3)2·6H2O under hydrothermal conditions. {[Zn(TPA)0.5(NH2TPA)0.5(bpmp)]·DMF·7H2O}n (framework 1) has an sra topology with a BET surface area of 756 m2 g-1. The microporous nature of the framework is apparent from the significant CO2 adsorption capacities observed at various temperatures: 57 cc g-1 at 283 K, 46 cc g-1 at 293 K, 37 cc g-1 at 303 K, and 30 cc g-1 at 313 K. The considerable CO2 adsorption may be caused by the existence of free carboxylate and amine substituents that interact with the gas molecules and micropores. At room temperature, the activated MOF readily converts CO2 into cyclic carbonates when a suspension of the MOF is bubbled with ambient air and different epoxides under solvent-free conditions. The amine groups located within the pores of the MOF interact with CO2 molecules, enhancing their sorption and conversion to cyclic carbonates. However, due to interpenetration within framework 1, only smaller size epoxides can be accommodated and converted to cyclic carbonates in good yields. Additionally, the effectiveness of the catalyst is further confirmed by the positive outcomes obtained from the hot filtration control test. Grand canonical Monte Carlo (GCMC) molecular simulations were utilized to gain a better understanding of molecular interactions. GCMC results are in line with the experiments. The substantial adsorption of CO2 can be ascribed to the strong intermolecular interactions that occur between the amine groups within the framework and the CO2 molecules.

Series of TM-OFs as a Platform for Efficient Catalysis and Multifunctional Luminescence Sensing.

Three novel porous transition-metal-organic frameworks (TM-OFs), formulated as [Co3(DCPN)2(μ2-OH2)4(H2O)4](DMF)2 (1), [Cd3(DCPN)2(μ2-OH2)4(H2O)4](DMF)2 (2), and [CdK(DCPN)(DMA)] (3), have been successfully prepared via solvothermal conditions based on a 5-(3',6'-dicarboxylic phenyl) nicotinic carboxylic acid (H3DCPN) ligand. 1 and 2 both have the same porous 3D network structure with the point symbol of {410·614·84}·{45·6}2 based on trinuclear ({Co3} or {Cd3}) clusters, indicating a one-dimensional porous channel, and possess excellent water and thermal stability; 3 also displays a porous 3D network structure with a 4-connected sra topology based on the heteronuclear metal cluster {CdK}. Complex 1 can be used to load Pd nanoparticles (Pd NPs) via a wetness impregnation strategy to obtain Pd@1. The reduction of nitrophenols (2-NP, 3-NP, 4-NP) by Pd@1 in aqueous solution shows outstanding conversion, excellent rate constants (k), and remarkable cycling stability due to the synergistic effect of complex 1 and Pd NPs. Luminescence sensing tests confirmed that 2 is a reliable multifunctional chemical sensor with high selectivity and sensitivity for low concentrations of Fe3+, Cr2O72-, CPFX, and NFX. Specifically, 2 shows a fluorescence enhancement behavior toward fluoroquinolone antibiotics (CPFX and NFX), which has not been reported previously in the literature. Moreover, the rational mechanism of fluorescence sensing was also systematically investigated by various detection means and theoretical calculations.

Temperature-Dependent Supramolecular Isomeric Zn(II)-Metal–Organic Frameworks and Their Guest Exchange

A pair of three-dimensional metal–organic framework supramolecular isomers (1a and 2a) prepared from the solvothermal reactions of Zn(NO3)2·4H2O, 1,4-bis(4-pyridyl)piperazine (bpp), and 4,4′-oxybis(benzoic acid) (H2obc) in different temperatures was structurally elucidated, and a series of guest exchanges on these isomers were performed without the loss of single crystallinity. At 110 and 130 °C in DMF/H2O, an 8-fold [4 + 4] interpenetrated coordination polymer {[Zn(bpp)(obc)]·3H2O}n (1a) with sra topology and a self-penetrated coordination polymer {[Zn3(bpp)3(obc)3]·2DMF·4H2O}n (2a) with a new topology were isolated, respectively. In the guest-exchange experiments, water molecules in isomer 1a were displaced by acetone and ethylene glycol molecules, while dimethylformamide molecules in isomer 2a were replaced by acetone and ethylene glycol as well as bulkier diethylene glycol due to its larger void. Photoluminescence properties of two isomers and their guest-exchanged products were also measured and discussed.

Three Cd(II)-based luminescent metal-organic frameworks constructed from the mixed-ligand strategy for highly selective detection of nitrobenzene

Three new Cd(II) luminescent metal-organic frameworks (LMOFs), namely {[Cd(bib) (bdc)]·DMF·H2O}n (1), {[Cd(bib)(ndc)(H2O)]·DMF}n (2) and {[Cd2(bib)2(bpdc)2]·1.5H2O} (3) (bib ​= ​1,3-bis(1-imidazolyl)benzene, H2bdc ​= ​1,4-benzenedicarboxylic acid, H2ndc ​= ​1,4-naphthalenedicarboxylic acid, H2bpdc ​= ​biphenyl-4,4′-dicarboxylic acid and DMF ​= ​N,N-dimethylformamide), have been synthesized by combining the V-shaped bib ligand and different dicarboxylate ligands under solvothermal conditions. Complex 1 displays a 4-fold interpenetrated 3D framework with sra topology. Complex 2 presents a 2D (4,4) layer structure derived from bib and ndc2− mixed spacers. Complex 3 is a 2-fold interpenetrated array based on 2D (4,4) wave-like coordinated layers. The structural diversity among these complexes can be realized by the abduction of linear dicarboxylate ligands. The results demonstrate that the length of dicarboxylate ligands makes an impact on the structural diversity. Moreover, the complexes 1–3 can be well dispersed in different solvents, which exhibit highly selective and sensitive detection for nitrobenzene (NB) over other solvents by means of fluorescence quenching effect. The work illuminates fine-tuning of structure and in turn sensing properties towards LMOFs based on the reasonable selection of organic ligands.

Europium-Functionalized Flexible Luminescent Zeolite-like Supramolecular Assembly for Ratiometric Anthrax Biomarker Determination.

Anthrax spores have been a determining risk to human beings and animals across the world. As such, the qualitative monitoring toward dipicolinic acid (DPA), the unique biomarker of bacillus anthracis, is highly desired and being moved forward in health management. Herein, a breathing zeolite-like supramolecular assembly (ZSA), with the sra topology and 1D hexagon channel, is designed by controlling the bridging angle of the ditopic ligand after systematic analysis in topology. The solvent-dependent dynamic behavior is illustrated by powder X-ray diffraction and reflected in tunable luminescent emission based on solvent polarity parameters. According to the structural result and theoretical analysis, Eu3+ is anchored within the framework to form a ratiometric luminescent sensor successfully because of the abundant potential active site. After DPA addition, the resulting composite shows a sensitive and selective response in the linear range of 0-7.0 μM stemmed from absorbance energy-transfer emission and preferential coordination. The work we presented here may enrich the sensing platforms containing lanthanides and expand the potential application of ZSAs in clinical analysis.

A series of lanthanide coordination polymers based on flexible bis‑(imidazole‑4,5‑dicarboxylate) ligand: Syntheses, structures and fluorescent properties

A series of lanthanide coordination polymers, namely {[Ln(HL)(H2O)2]·H2O}n (Ln = Ce(1), Pr(2), Nd(3), Eu(4) and Tb(5); H4L = 1,1′‑(propane‑1,3‑diyl)bis(1H‑imidazole‑4,5‑dicarboxylic acid)) have been synthesized under hydrothermal conditions and characterized by infrared spectroscopy, element analysis, single-crystal X-ray diffraction, powder X-ray diffraction and thermogravimetric analyses. These isostructural complexes exhibit a 3D framework with a sra topology built by HL3− anions μ4–bridging metal ions through two IDC groups in different coordination modes. The luminescent property of complexes containing Eu(III) and Tb(III) have also been investigated in detail.

Near-White Light Emission from Lead(II) Metal-Organic Frameworks.

Reaction of bpy (bpy = 4,4'-bipyridine) with Pb(OAc)2·3H2O in DMF (DMF = dimethylformamide) afforded a metal-organic framework (MOF), [Pb2(μ-bpy)(μ-O2CCH3)2(μ-O2CCH3)2]·H2O (1). Reaction of bpy with Pb(O2CCF3)2 in a methanol and chloroform mixture furnished another MOF, [Pb(μ-bpy)(μ-O2CCF3)2]·1/2CHCl3 (2). However, the reaction of bpy with Pb(OAc)2·3H2O in the presence of trifluoroacetic acid in a similar reaction condition yielded a hydrogen-bonded zwitter-ionic complex of Pb(II), [Pb(bpy-H)2(O2CCF3)4] (3). All compounds have been characterized by single crystal X-ray crystallography, FT-IR, and 1H NMR spectroscopies. Compound 1 forms four heptacoordinated Pb(II) joined by (OCCH3)-O- linkages, resulting in a 3D noninterpenetrated MOF net with a four-connected uninodal sra (SrAl2) topology. However, in 2, tetra-connected Pb4(O2CCF3)8 cluster units are linked further through eight bpy ligands to furnish a doubly interpenetrated MOF with a new topology but having the very similar connectivity of 1, whereas 3 forms a zigzag hydrogen-bonded chain structure. The variation of carboxylate anions, pH of the reaction medium, and the ratio of the reactants profoundly affected the final topological structure of the compounds synthesized. The solid-state photoluminescence of 1-3 was investigated at room temperature. Interestingly 1, 2, and 3 achieved close to white light emission when excited at 329, 376, and 330 nm, respectively. The systematic understanding of the photophysical properties of analogous Pb-based compounds may open new perspectives for developing single-phase white-light-emitting materials using Pb(II) based MOFs.

Aqueous detection of antibiotics with a Cd(II)-based metal-organic framework constructed by a tetra(1,2,4-triazole)-functionalized-bis(triphenylamine) ligand

A Cd(II)-based MOF (Cd-TTPBA-4) with sra topology is constructed by a tetra(1,2,4-triazole)-functionalized-bis(triphenylamine) ligand (TTPBA-4) showing two types of 1-D channels with partial channel walls built from columnar stacks of non-coordinated triazole-terminated arms. Particularly, it constitutes a rare example of MOF-based luminescent sensor for aqueous selective detection of NZF (nitrofurazone) and NFT (nitrofurantoin) antibiotics.

Two luminescent Cd(II)-MOFs based on bis(benzimidazole) and aromatic dicarboxylate ligands as chemosensor for highly selective sensing of Fe3+

Two new metal–organic frameworks (MOFs), {[Cd(L)(2-NTP)]·0.25H2O}n (1) and [Cd(L)(4-CPA)]n (2) (L = 1,6-bis(5,6-dimethylbenzimidazolyl)hexane, 2-H2NTP = 2-nitroterephthalic acid, 4-H2CPA = 4-carboxyphenoxyacetic acid) were synthesized and characterized by infrared spectroscopy, elemental analysis, and powder X-ray diffraction. The structural analysis reveals that 1 exhibits a 3D framework, which can be classified as a 4-connected sra topology, while 2 displays a 2D (6,3) layered structure. The thermal behaviors, luminescence properties of two compounds are investigated. The luminescence sensing experiments reveal that both MOFs display efficient detection toward Fe3+ ion through fluorescence quenching in the aqueous solution.

Six metal-organic frameworks assembled from asymmetric triazole carboxylate ligands: Synthesis, crystal structures, photoluminescence properties and antibacterial activities

Abstract Based on an asymmetric 1-(2-carboxyethyl)-1H-1,2,4-triazole-3-carboxylic acid (H2ctp), six new MOFs [Cd(ctp)(H2O)]n (1), [Cd2(ctp)2(phen)]n (2) [phen = 1,10-Phenanthroline monohydrate], [Cd2(ctp)2(pbbbm)(H2O)2]n (3) [pbbbm = 1,4-bis(benzimidazole-1-ylmethyl)benzene)], [Mn(ctp)(H2O)]n (4), {[Pb2(ctp)2]·H2O}n (5) and [Cu(ctp)(H2O)2]n (6) have been synthesized and structurally characterized by single-crystal X-ray diffraction, elemental analysis and IR spectroscopy. 1, 4 and 5 display (4,4)-connected 3-D frameworks which all can be simplified into the Schlafli symbol of (42·63·8) with sra topology, while 2 is also a (4,4)-connected 3-D network which has the Schlafli symbol of (42·84) with pts topology. 3 exhibits a 2-D structure with 3,4L83 topology and 6 is a 1-D chain structure. The fluorescent properties of 1–3 and 5 have been studied in the solid state at room temperature. 5 has significantly stronger fluorescence emission than 1–3 due to its crystal structure features. The antibacterial activities of 1–6 against four strains bacteria of Bacillus subtilis, Staphylococcus aureus, Salmonella enteritidis and Escherichia coli have been examined. The results indicated that 2 has better activity against Bacillus subtilis than 1, 3, 4 and 6 due to the effect of chelation, auxiliary ligands and the Cd(II) ion with the feature of strong toxicity.

Syntheses, structures, luminescent properties and antibacterial activities of seven polymers based on an asymmetric triazole dicarboxylate ligand

By controlling different reaction conditions in hydrothermal process, seven metal salts react with 1-(carboxymethyl)-1H-1,2,4-triazole-3-carboxylic acid (H2cta), which result in seven new polymers, namely, [Cd(cta)(H2O)]n (1), [La(cta)(OH)]n (2), {[Pb(cta)]·H2O}n (3), [Sr(cta)(H2O)2]n (4), {[Zn2(cta)2(H2SO4)]·2CH3CH2OH}n (5), [Mn(cta)(H2O)2]n (6), [Ba(cta)(H2O)3]n (7). Their structures have been determined by single-crystal X-ray diffraction analysis and characterized by elemental analysis, IR spectroscopy. Polymers 1–2 are isostructural and topological analysis revealed that 1–4 can be described as a sra topology with Schläfli symbol of (42·63·8). 5 possesses two-dimensional bilayer network with a total potential solvent accessible volume of 27.1%. 6 exhibits a 2D framework sql topology with Schläfli symbol of (44·62). 7 crystallizes in the triclinic crystal system of P1 space group and can be considered as a (3,8)-connected tfz-d topology with the point symbol of (43)2(46·618·84). The luminescent properties (1–5, 7) are performed in the solid state. Remarkably, 3 exhibits strong fluorescent emission in the solid state at room temperature, which be attributed to the corresponding structure factors. In addition, the microbiological properties of 1–7 were also studied. Compared with six clinical drugs, 3 and 5 showed pretty good antibacterial activities. The higher activities of 3 and 5 may be due to the chelation effect or to the influence of the metal ion on the normal cell process. Solid state thermal analyses of some polymers indicate the formation of the metal oxide as an end product.

Temperature and solvent controlled syntheses of six hydrous 5-(3-pyridylmethoxy)isophthalate Cd(II) coordination polymers

Six hydrous Cd(II) coordination polymers based on a scorpion-like 5-(3-pyridylmethoxy)isophthalic acid (H2L), namely {[CdL(H2O)]·2H2O}n (1), [Cd4L4(H2O)4]n (2), [CdL(H2O)]n (3), [CdL(H2O)2]n (4), {[CdL(H2O)]·H2O}n (5) and [CdL]n (6), were hydrothermally synthesized and characterized by EA, IR, PXRD, TG-DSC and X-ray structural analysis. Temperature and solvent play crucial roles in the preparation of the coordination polymers. Complexes 1–3 were prepared in a H2O-DMF (6:2) solvent system at slightly different temperature (85, 100 and 120°C). Complexes 4–6 were prepared in different H2O-DMF solvents (6:3 and 8:2) and H2O-MeCN (3:6) solvent. These complexes possess different coordinated and/or lattice water molecules, and exhibit structural diversity and various topology nets. Complex 1 is a 2D double-layered coordination polymer. Complex 2 features a 3D porous framework with irl topology. Complex 3 displays a 2D double-layered network. Complex 4 is a 3D coordination polymer with sra topology. Complex 5 exhibits a 3D wave-like framework with sra topology. Complex 6 is a 3D coordination polymer with self-catenated hxg-d topology. 5-(3-Pyridylmethoxy)isophthalate adopts three types of coordination modes. These complexes exhibit higher thermal stability and emit strong luminescence.

A rare 3D chloro-laced Mn(II) metal-organic framework to show sensitive probing effect to Hg2+

Two 3D Mn(II) metal-organic frameworks (MOFs), [Mn(L-Cl)(DMA)](H2O) (1) and Mn(L-CH3)(DMA) (2) (H2L-Cl = 2,2’-dichloro-4,4’-azodibenzoic acid, H2L-CH3 = 2,2’-dimethyl-4,4’-azodibenzoic acid) were synthesized under similar solvothermal condition. Both MOFs crystallize in the orthorhombic system and show the 3D rod-packing networks in 2-fold interpenetrated pattern with sra topology. Due to the different substituent laces of MOFs (–Cl vs –CH3), only MOF 1 shows highly selective and sensitive fluorescence sensing effect for detecting Hg2+ ion.

Syntheses, Structures and Characterization of Four Metal-Organic Frameworks constructed by 2,2′,6,6′-Tetramethoxy-4,4′-biphenyldicarboxylic Acid

Four metal-organic frameworks (MOFs), {[Mn3.5L(OH)(HCOO)4(DMF)]·H2O} (1), {[In2.5L2O(OH)1.5(H2O)2]·DMF·CH3CN·2H2O} (2), {[Pb4L3O(DMA)]·CH3CN} (3), and {[LaL(NO3)(DMF)2]·2H2O} (4) were synthesized by utilizing the ligand 2,2′,6,6′-tetramethoxy-4,4′-biphenyldicarboxylic acid (H2L) via solvothermal methods. All MOFs were characterized by single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis, and infrared spectroscopy. In 1, the Mn2+ ions are interconnected by formic groups in situ produced via DMF decomposition to form a rare 2D macrocyclic plane, which is further linked by L2– to construct the final 3D network. In 2, 1D zip-like infinite chain is formed and then interconnected to build the 3D framework. In 3, a [Pb6(μ4-O)2(O2C)10(DMA)2] cluster with a centrosymmetric [Pb6(μ4-O)2]8+ octahedral core is formed in the 3D structure. In 4, the La3+ ions are connected with each other through carboxylate groups of L2– to generate 1D zigzag chain, which is further linked by L2– to construct a 3D network with sra topology. Solid photoluminescence properties of 3 and 4 were also investigated.

Structural variety in ytterbium dicarboxylate frameworks and in situ study diffraction of their solvothermal crystallisation

The ytterbium 1,4-benzenedicarboxylate (BDC) framework [Yb2(BDC)3(DMF)2]·H2O (1) crystallises from a N,N-dimethylformamide (DMF)-rich solution at 80–120 °C. (1) is constructed from infinite chains of dicarboxylate-bridged seven-coordinate Yb atoms, cross-linked in two directions by BDC to yield diamond-shaped channels (sra topology) lined by coordinated DMF molecules and occluded water. Increasing the water content in the synthesis solution yields a material with more crystal water Yb2(BDC)3(DMF)2(H2O)2 (2), in which the Yb centres are eight-coordinate and form dimers bridged by BDC to give two interpenetrating networks of pcu (α-Po) topology. Upon extended reaction in this water-rich solvent mixture, an alternative phase is formed: an anhydrous mixed BDC-formate, Yb(BDC)(HCO2), (3), which has a pillared, layered structure, with formate produced by hydrolysis of the DMF. An isoreticular version of (2) can also be formed under similar conditions using 2,6-naphthalene-dicarboxylate (NDC) as linker: [Yb2(NDC)3(H2O)4]·2DMF (4). Despite their different structures, (1) and (2) are calcined to a common porous, desolvated phase Yb2(BDC)3 at 300 °C. Using high energy X-rays at Diamond Light Source we are able to penetrate the solvothermal reaction vessels and to follow the formation of (1) and (2) in real time. This allows accurate crystallisation curves to be obtained from which qualitative kinetic information is extracted. Importantly, the high angular resolution of the in situ powder XRD patterns allows refinement of crystal structure: this permits the temporal evolution of unit cell parameters to be followed, which are ascribed to changes in coordinated solvent composition within the materials during their formation, while analysis of phase fraction allows kinetic parameters to be quantified using the nucleation-growth model of Gualtieri.

Construction of noninterpenetrating and interpenetrating Co(ii) networks with halogenated carboxylate modulated by auxiliary N-donor co-ligands: structural diversity, electrochemical and photocatalytic properties.

Six Co(ii)-based coordination polymers (CPs) with characteristic frameworks and topologies-namely, [Co(L1)(DCTP)]n (1), [Co(L2)(DCTP)]n (2), [Co(L3)(DCTP)]n (3), {[Co3(L4)3(DCTP)3·H2O]·H2O}n (4), [Co(L5)1.5(DCTP)]n (5) and [Co(L6)(DCTP)]n (6)-were successfully hydrothermally synthesized by employing the halogenated linear ligand 2,5-dichloroterephthalic acid (H2DCTP). The interpenetrated structures could be rationally modulated by auxiliary N-donor co-ligands containing 1,1'-(1,4-butanediyl)bis-1H-benzimidazole (L1), 1,4-bis(5,6-dimethylbenzimidazol-1-yl)-2-butylene (L2), 1,2-bis(2-methylbenzimidazol-1-ylmethyl)benzene (L3), 1,4-bis(2-methylbenzimidazol-1-ylmethyl)benzene (L4), 1,2-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene (L5) and 1,4-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene (L6). These diaphanous crystals were clearly characterized by elemental analysis, infrared (IR) spectra and X-ray powder diffraction (XRPD) as well as single-crystal X-ray diffraction analysis. With the aid of the flexible N-donor co-ligands, CP 1 occupies a non-interpenetrated 2D sheet with the point symbol {44·62} sql net topology, CP 2 possesses a 3D hexagon-shaped network with the point symbol {66} three-fold interpenetrated sqc6 topology, CP 3 exhibits a 2D layer with the point symbol {44·62} sql net topology, CP 4 reveals an unusual 3D framework with the point symbol {42·63·8} three-fold interpenetrated sra topology, CP 5 has a 3D hexagon-shaped network with the point symbol {66} two-fold interpenetrated sqc6 topology, while CP 6 displays a 3D hexagon-shaped network with the point symbol {66} three-fold interpenetrated sqc6 topology. The diverse structures of CPs 1-6 illustrate that the substitute group and position of the methyl group of the bis(benzimidazole) derivatives play a significant role in the assembly of such interpenetrated frameworks. Moreover, luminescence properties and thermal behavior, as well as the electrochemical and photocatalytic properties of CPs 1-6 on the degradation of methylene blue, are also presented.

Lanthanide Metal-Organic Frameworks with Six-Coordinated Ln(III) Ions and Free Functional Organic Sites for Adsorptions and Extensive Catalytic Activities

Three chelating-amino-functionalized lanthanide metal-organic frameworks, Y-DDQ, Dy-DDQ and Eu-DDQ, were synthesized with a flexible dicarboxylate ligand based on quinoxaline (H2DDQ = N, N′-dibenzoic acid-2,3-diaminoquinoxaline). The three-dimensional framework is constructed by the H2DDQ linkers connecting the zigzag ladders, showing a net of sra topology. In the structures, one kind of Ln(III) ions metal centers are six-coordinated and thus can potentially behave as open metal sites (OMSs), while the free chelating amino groups can act as free functional organic sites (FOSs). The N2 and Ar adsorption behaviors indicate that these Ln-DDQ exhibits stable microporous frameworks with high surface area after remove of the solvents. Owing to presence of OMSs and FOSs, these MOFs show good ability of CO2, dyes captures and Lewis acid catalyst for cyanosilylation reaction. In view of the existing FOSs in the framework, Pd NPs were immobilized onto the MOFs through graft interactions between free chelating amino groups and metal ions precursor using postsynthetic modification. The well dispersed Pd@Ln-DDQs exhibit efficient and recyclable catalytic reduction of 4-nitrophenol to 4-aminophenol, and they can also act as an excellent catalyst for Suzuki-Miyaura cross-coupling reactions with the exposed Pd NPs.

Homochiral zinc benzene-1,3,5-tricarboxylate coordination networks with a chiral nitrogen ligand or template: Spontaneous resolution of a twofold interpenetrated 2D sql (4,4) network and formation of enantiopure 3D sra (SrAl2) networks

A pair of homochiral enantiomorphic two-fold interpenetrated, mixed-ligand coordination polymers (CPs), 2D-{[Zn(μ-Hbtc)(μ-R-btrip)]·H2O}n1 and 2D-{[Zn(μ-Hbtc)(μ-S-btrip)]·H2O}n2, were found in a racemic conglomerate in space group P212121 with enantiomorphous crystals by spontaneous resolution (H3btc=benzene-1,3,5-tricarboxylic acid, trimesic acid). The racemic ligand 1,2-bis(1,2,4-triazol-4-yl)propane (rac- or R,S-btrip) spontaneously resolves upon coordination to Zn(II) and crystallization from Zn(NO3)2·6H2O for 1 or ZnBr2 for 2, in presence of the trimesic acid (H3btc) under hydrothermal conditions. Single-crystal analysis of 1 and 2 revealed a chiral two-dimensional sql (4,4) network based on the interconnection of {Zn(Hbtc)} and {Zn(btrip)} chains at the Zn atom. Each 2D sql network is 2-fold interpenetrated by a symmetry related net. The interpenetration appears controlled by triazole–C–H⋯N hydrogen bonds. When the enantiopure Schiff base 2-((E)-(1-(4-methoxyphenyl)ethylamino)methyl)phenol (N-(1-(4-methoxyphenyl)ethyl)salicylaldimine) was reacted with ZnSO4 and H3btc in water/methanol the imine CN bond hydrolyzed retro-synthetically to the aldehyde and the amine which was protonated to the ammonium cation. The in-situ formed enantiopure (R) or (S)-1-(4-methoxyphenyl)ethylammonium cation was incorporated as a template in the crystallization of the anionic 3D-network {bis(benzene-1,3,5-tricarboxylato-κ4O:O′:O″:O‴′)dizinc(II)}, {[Zn2(μ4-btc)2]2−}n in the chiral compounds {[(R)- or (S)-4-CH3OC6H4CH(CH3)NH3]2[Zn2(μ4-btc)2]·2H2O}n (3 or 4, respectively). The 3D-network exhibited sra (SrAl2, zeolite ABW) topology. The ammonium cations are positioned by charge-assisted N–H(+)⋯(−)O (carboxylato) H-bonds and charge-assisted π-stacking in the anionic framework.

Construction of New Coordination Polymers from 4’-(2,4-disulfophenyl)- 3,2’:6’3”-terpyridine: Polymorphism, pH-dependent syntheses, structures, and properties

Nine new coordination compounds, namely, [Co(HDSPTP)2(H2O)4]·4H2O (H2DSPTP=4’-(2,4-disulfophenyl)-3,2’:6’3”-terpyridine, 1 and 2), {[Ni(DSPTP)(H2O)4]·3H2O}n (3), {[Cu(HDSPTP)2(H2O)3]·8H2O}n (4), {[Cu(HDSPTP)2(H2O)3]·6H2O}n (5), {[Cu(DSPTP)(H2O)2]·H2O}n (6), {[Zn(DSPTP)(H2O)2]·2H2O}n (7), {[Cd(DSPTP)(H2O)2]·2H2O}n (8), and [Ag2(DSPTP)(H2O)]n (9), were constructed based on a new ligand containing both terpyridyl and sulfo groups. The reactions of H2DSPTP with Co(NO3)2.6H2O resulted in two mononuclear complexes (compounds 1 and 2). They are polymorphisms that display different hydrogen bonding networks. They are selectively synthesized by altering the added alkalis. The reaction of H2DSPTP with Ni(NO3)2·6H2O resulted in a 1D “S-shaped” coordination chain (compound 3). The reactions of Cu(II) with H2DSPTP at different pH value resulted in the following three compounds: two kinds of 1D chains obtained at pH 3.0 and 4.0 for compounds 4 and 5, respectively, and a 3D framework based on binuclear ring units with 4-connected sra topology (Compound 6). The reactions of H2DSPTP with ds-block ions resulted in the following three compounds: a Zn(II) (compound 7) and a Cd(II) (compound 8) 3D frameworks with structures similar to that in compound 6, and a 3D framework based on tetranuclear Ag(I) SBUs with binodal (4,8)-connected flu type 3D framework topology. The structural diversity is mainly attributed to the rich coordination modes (from monodentate to µ7-mode) and conformations (cis–cis and cis–trans) of HDSPTP−/DSPTP2− ligands and the metal center and can be controllable synthesized by altering the alkalis, and pH value. Thermal stability of all compounds was performed, and the thermal behaviors of compounds 6 and 8 were further explored by PXRD. Compound 6 exhibits low thermal stability and undergo a crystalline–crystalline-amorphous phase transition as temperature increases from 25°C to 200°C, and show amorphous–crystalline phase transition when rehydrated. However, compound 8 exhibits high thermal stability above 500°C. Its crystalline phase can retain above 300°C and undergo a crystalline–crystalline phase transition as temperature increased to 400°C, and transit back to compound 8 when rehydrated. Moreover, luminescence properties of compounds 7–9 were also investigated.

Syntheses, Structures and Luminescent Properties of 2D and 3D Cadmium(II) Coordination Polymers Derived from Two Isomeric Perchlorinated Benzenedicarboxylates

AbstractThe coordination polymers {[Cd(o‐BDC‐Cl4)(H2O)2]·EtOH}n (1) and {[Cd(p‐BDC‐Cl4)(DMF)]·H2O}n (2) (o‐BDC‐Cl4 = tetrachlorophthalate and p‐BDC‐Cl4 = tetrachloroterephthalate) were synthesized in different solvents using two isomeric tetrachlorinated benzenedicarboxylic acids. Complex 1 based on o‐BDC‐Cl4 features an extremely rare 2D trinodal (3,4,6)‐connected network constructed by the combination of 1D [Cd‐H2O]n chains and 1D [Cd2(o‐BDC‐Cl4)2]n loop‐like motifs. Complex 2 based on p‐BDC‐Cl4 has a 3D framework and shows a uninodal 4‐connected sra topology. Complexes 1 and 2 were characterized by elemental analyses, IR spectroscopy, single‐crystal X‐ray diffraction and thermogravimetric (TG) analyses. The photoluminescence of 1 and 2 were investigated in the solid state at room temperature.