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This paper presents a novel methodology for obtaining the free energy profiles and the self-diffusivity of gases in crystalline microporous materials. The proposed approach is based on X-ray diffraction performed in situ on powder rather than single crystal samples. As proof of concept, we derive the self-diffusion properties of CO2 and CH4 in a metal–organic framework, CAU-10-H. The free energy profiles and self-diffusivity values acquired experimentally using the proposed methodology match those obtained through molecular simulations. This XRD-based methodology can be used for the design of MOFs for membrane gas separation. [ABSTRACT FROM AUTHOR]

In this work, we investigate the vapor-assisted synthesis of the metal–organic framework MOF-74 starting from three metal oxides (ZnO, CoO, and MgO). Depending on the nature of the added vapor (H2O, DMF, DMSO), the metal oxide, and the temperature, the outcome of the reaction can be directed towards the desired porous phase. Ex situ and in situ XRD measurements reveal the formation of an intermediate phase during the reaction of MgO with H4dobdc, while the MOF-74 phase forms directly for ZnO and CoO. The reduced CO2 uptake of the resulting materials compared to solvothermally prepared MOFs might be offset by the convenience of the presented route and the promise of a high space time yield. [ABSTRACT FROM AUTHOR]

High-pressure single crystal X-ray diffraction has been used to probe framework–guest interactions in the Co-based metal–organic framework ZIF-67 during compression in 4 : 1 MeOH : EtOH and liquid nitrogen (LN2) pressure-transmitting media. On increasing pressure, the structure undergoes a gate-opening phase transition, characterised by rotation of the 2-methylimidazolate ligand, at 1.57 GPa in MeOH : EtOH and at 0.43 GPa LN2. Adsorption of N2 occurred progressively with increasing pressure into 6 adsorption sites and resulted in the first documented instance of pressure-induced solvatochromism in ZIF-67. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) as types of proton conductive materials have attracted much attention. Here, an acylamide-functionalized 3D MOF, [Ni3(TPBTC)2(stp)2(H2O)4]·2DMA·32H2O, has been successfully constructed via combining Ni(NO3)2, TPBTC (TPBTC = benzene-1,3,5-tricarboxylic acid tris-pyridin-4-ylamide) and 2-H2stp (2-H2stp = 2-sulfoterephthalic acid monosodium salt) under solvothermal conditions. Single-crystal X-ray diffraction revealed that there are uncoordinated guest DMA molecules in the pores of the compound. On removal of guest DMA molecules, the proton conductivity of the compound increased to 2.25 × 10−3 S cm−1 at 80 °C and 98% RH which is about 110 times that of the original material. It is hoped that this work can provide essential insight for designing and obtaining improved crystalline-state proton conducting materials by considering the influences of guest molecules on proton conduction properties of porous materials. [ABSTRACT FROM AUTHOR]

A new mixed linker metal–organic framework (MOF) has been synthesized from a copper-based metal–organic polyhedron (MOP-1) and 2,2′-bipyridine (2,2′-bipy). The CuMOF-Bipy with a formula of [Cu2(2,2′-bpy)2(m-BDC)2]n is comprised of a binuclear Cu(II) node coordinated to 2,2′-bipy, and isophthalic acid (m-BDC), which bridges to neighboring nodes. The crystal structure of CuMOF-Bipy consists of a stacked two-dimensional framework with the sql topology. CuMOF-Bipy was characterized by single-crystal X-ray diffraction (SC-XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and CO2 sorption. CuMOF-Bipy was shown to have one-dimensional sinusoidal channels that allow diffusion of CO2 but not N2. [ABSTRACT FROM AUTHOR]

Due to the excellent fluorescence properties of organic fluorescent ligand 4,7-bi(1H-imidazol-1-yl)benzo-[2,1,3]thiadiazole (BIBT), luminescent coordination polymers (CPs) or metal–organic frameworks constructed from BIBT have received our attention. In this work, by the self-assembly of BIBT and Zn(II) ions, the formation of a two-dimensional (2D) CP with a formula [Zn2(BIBT)(AIPA)2]n (JXUST-17, H2AIPA = 5-aminoisophthalic acid) has been achieved. X-ray single-crystal diffraction analysis reveals that the adjacent ZnII ions are connected by amino and carboxylate groups from AIPA2− ligands to form a 2D layer structure and the neighboring layers are further linked by BIBT ligands to construct a 2D double-layer structure. Luminescence investigation suggests that JXUST-17 not only possesses excellent detection capability but also exhibits excellent selectivity toward nitrofurantoin (NFT) and 2.6-dichloro-4-nitroaniline (DCN). Furthermore, mixed matrix membranes are developed by the dispersion of JXUST-17 with polymethyl methacrylate in DMA solution to realize a rapid and visualizable luminescence response towards NFT. [ABSTRACT FROM AUTHOR]

Two novel 2D lanthanide metal–organic frameworks (Ln-MOFs), namely {[Eu2(DBTA)3(DMF)2]·DMF}n (1) and {[Tb2(DBTA)3(DMF)2]·DMF}n (2) (H2DBTA = 2,5-dibromoterephthalic acid), have been successfully synthesized by the solvothermal method. Single-crystal X-ray diffraction results proved that the complexes possess the same topological structure of a (42·6)2(42·84)(47·63)2-connected net. The recognition of CN− from interfering anions with a low detection limit by "turn-off" luminescence makes them promising candidates for the highly selective and sensitive detection of the cyanide ion. The Ln-MOFs 1 and 2 exhibit excellent chemical sensing properties for CN− with efficiency, selectivity, and excellent performance in various mixed anions. The evaluation parameters, including the quenching constant and detection limit, have been investigated to obtain the detection performance for CN−. [ABSTRACT FROM AUTHOR]

A zeolitic imidazolate framework-8 (ZIF-8) electrode is a good candidate as an anode material. However, further developments of ZIF-8 electrodes present a major challenge owing to their excessively time-consuming preparation processes. To overcome this issue, here, we prepared a ZIF-8 material within 15 min by the microwave-assisted solvothermal technique. The structural properties of the samples before and after annealing were examined by XRD, whereas the local atomic and electronic structures were studied by X-ray absorption spectroscopy (XAS). XRD data exhibited the formation of the ZIF-8 material. XRD data also affirmed the formation of an amorphous phase ZnNC after annealing under N2. XAS results revealed that the ZIF-8 material converted to ZnNC after annealing under N2. Moreover, the morphology was investigated by HRTEM with elemental analysis. The surface areas of ZIF-8 and ZnNC samples were studied and found to be 1610 cm2 g-1 and 276 cm2 g-1, respectively. The ZnNC material revealed higher discharge and charge capacities of B826 and 447 mA h g-1, respectively. The coulombic efficiency of the ZnNC electrode considerably improved from 52% in the 1st cycle to 95% in the 4th cycle, signifying a good stability over the subsequent cycles. The satisfactory structural and electrochemical characteristics of the ZnNC electrode make this electrode a promising anode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Highly connected molecular building blocks (MBBs) have been demonstrated to play a crucial role in reticular chemistry, particularly in predicting the topologies of metal–organic frameworks. Metal phosphonate clusters exhibit considerable advantages in constructing high-connectivity MBBs, owing to the multiple coordination modes offered by phosphonic ligands. Herein, four metal (M = CoII, MnII) phosphonocarboxylate frameworks (CoPCF-1,2 and MnPCF-1,2) were successfully prepared under solvothermal conditions by utilizing the phosphonocarboxylic ligand, 4′-phosphonobiphenyl-3,5-dicarboxylic acid (H4pbpdc), and their structural characterization was performed using single-crystal X-ray diffraction (SCXRD). The structures feature a duodenary nuclear M12(µ3-OH)2(CO2)12(PO3)6(DMF)6/(CH3COO)4.5 cluster, bearing resemblance to the well-known Wells–Dawson ion from polyoxometallate chemistry. It is the first time a Wells–Dawson type cage has served as an 18-connected molecular building block, forming two kinds of porous metal phosphonocarboxylate frameworks with novel (3,18)-connected gez and gea topologies. Their permanent porosities were confirmed through N2 adsorption studies. Notably, the MBB Co12 cluster-based CoPCF-1 shows a loss and recovery process of µ3-OH through single-crystal-to-single-crystal (SCSC) transformation. The magnetic properties of the four compounds exhibit antiferromagnetic behavior. [ABSTRACT FROM AUTHOR]

Developing highly sensitive MOF-based probes for environmental contaminant detection is of much importance and challenging. Here, two new three-dimensional lanthanide metal–organic frameworks (Ln-MOFs), {[Eu(DTA)1.5(H2O)]·H2O}n (Eu-DTA) and [Tb(DTA)(C2O4)0.5(H2O)]n (Tb-DTA) (H2DTA = 2,5-di(1H-imidazol-1-yl)terephthalic acid), are successfully synthesized via a hydrothermal reaction. Single-crystal X-ray diffraction analyses demonstrate that the extended π conjugated ligand plays an important role in the coordination mode and topologies. Eu-DTA possesses a 4,6-connected three-dimensional topological structure, while Tb-DTA exhibits a 4,5-connected three-dimensional framework. Interestingly, the rich uncoordinated nitrogen or oxygen atoms in these two structures can be used as Lewis basic sites, showing strong sensitivity to metal ions and solvent molecules. Furthermore, luminescence and sensing studies reveal that Eu-DTA and Tb-DTA can sensitively and simultaneously detect Fe3+ ions and nitrobenzene, which suggests that the two Ln-MOFs are promising bifunctional luminescence sensors. The quenching mechanism for Fe3+ has been discussed in detail. [ABSTRACT FROM AUTHOR]

Solvothermal reactions of a novel multidentate ligand, 2,5-bis-(1,2,4-triazol-1-yl)-terephthalic acid (H2TTPA), with MnCl2 afforded three structurally distinct coordination polymers with the same formula, [Mn(TTPA)·H2O]n (Mn-(1–3)). Single-crystal X-ray diffraction analyses show that complex Mn-1 exhibits a binodal 3D framework with Schläfli symbol {42·6·83}, while Mn-2 displays a trinodal 3D framework with point symbol {416·612}{44·62}2. Mn-3 shows a novel complicated topology, which is characterized as a 4,5,6-c net 3D framework. Further magnetic analysis discloses the antiferromagnetic (AF) behavior between Mn(II) ions in complexes Mn-2 and Mn-3. [ABSTRACT FROM AUTHOR]

A new 3D Ag(I)-based HE-MOFs, [Ag2(TABT)(NO3)2]n, where TABT represents 4,4′,5,5′-tetraamine-3,3′-bis-1,2,4-triazole, was synthesized and fully characterized by single-crystal X-ray diffraction, IR, 1H-NMR and elemental analyses. Its thermal behaviors were investigated by thermogravimetry and differential scanning calorimetry (TG-DSC) techniques while the thermo-kinetic parameters of exothermic process were calculated by Kissinger and Ozawa methods. The results indicate that the compound possesses an excellent thermal stability with a high decomposition temperature up to 301.2 °C. In addition, its detonation properties and sensitivity suggest that the title Ag-based salt can be used as a potential explosive. [ABSTRACT FROM AUTHOR]

Interpenetrated multicomponent MIL-142(Sc) MOFs were synthesised using the planar tritopic (4,4′,4′′-(1,3,5-triazine-2,4,6-triyl)tribenzoate, TATB, or 4,4′,4′′-(pyridine-2,4,6-triyl)tribenzoate, PTB) and linear ditopic (1,4-benzenedicarboxylate, BDC, or 2-amino or 2-nitro-1,4-benzenedicarboxylate (NH2- or NO2-BDC) linkers. Structure solution of the MIL-142(Sc)-TATB series from single crystal X-ray diffraction in space group R3¯m reveals regioselective ordering of bulky NO2 groups in MIL-142(Sc)-TATB-NO2. Use of 1,3,5-benzenetribenzoate (BTB) favours instead the mesoporous Sc-BTB, the PTB analogue of which forms in the absence of BDC. The materials are highly porous: MIL-142(Sc)-TATB-BDC has a pore volume of 0.70 cm3 g−1. [ABSTRACT FROM AUTHOR]

Three new alkaline earth metal–organic frameworks (MOFs), namely [Mg2(DMTDC)2(DMF)3(H2O)2]·2DMF·2H2O (1), [Ca(DMTDC)(DMF)] (2) and [Sr(DMTDC)(DMF)] (3), have been synthesized under solvothermal conditions by using a thiophene-functionalized dicarboxylate ligand, 3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylic acid (H2DMTDC). Single-crystal X-ray diffraction analyses demonstrate that the metal ion radii play an important role in coordination numbers and topologies, i.e., hexa-coordinated Mg2+ in 1 gives a two-dimensional layered framework with an sql net, while octa-coordinated Ca2+/Sr2+ in 2/3 exhibit a three-dimensional framework with lvt nets. All frameworks show a one-dimensional rhombus-shaped channel that is occupied by DMF and/or water molecules. Photoluminescence studies reveal that 1–3 can be used as fast-response fluorescence sensors for the sensitive detection of Fe3+ ions with favorable recyclability through fluorescence quenching. [ABSTRACT FROM AUTHOR]

Single-crystal-to-single-crystal post-synthetic modifications (PSMs) of Lanthanide Organic Frameworks (LOFs) {[Ln2(H2L)3(DMF)4]·2DMF}n (Ln = Gd, 1 and Eu, 2; H4L = 2,5-dihydroxyterephthalic acid; DMF = dimethylformamide), carried out by treatment with (a) chloroform or (b) an imidazole solution in chloroform, yielded respectively isostructural {[Ln2(H2L)3(DMF)4]·CHCl3}n (Ln = Gd, 3; Eu, 4) or {[Ln2(H2L)3(Im)4][Ln2(H2L)3(Im)2(H2O)2]·6Im·2CHCl3}n (Ln = Gd, 5; Eu, 6). Single crystal X-ray diffraction studies of 5 showed two different regularly alternating dimeric units in the LOF and two regularly alternating cavities with different guest molecules. All compounds revert to the parent LOF, 1 or 2, when treated with DMF at 90 °C for 8 h. Europium-LOFs (2, 4 and 6) showed a faint red emission that progressively gained intensity upon cooling from RT to liquid nitrogen temperature. This behaviour was exploited to develop a family of luminescent thermometers whose characteristics were affected by the structural and coordinative modifications induced by PSMs. [ABSTRACT FROM AUTHOR]

Six Zn/Cd metal–organic frameworks (MOFs), {[Zn2(dppa)(bpy)2(H2O)]·H2O}n (1), {[Zn2(dppa)(phen)2(H2O)]·3H2O}n (2), [Cd(H2dppa)(bpy)]n (3), {[Cd2(dppa)(dye)]·H2O}n (4), {[Cd4(dppa)2(H2O)9]·H2O}n (5) and {[Cd2(dppa)(bpe)2(H2O)]·H2O}n (6) (H4dppa = 5-(3′4′-dicarboxylphenoxy)isophthalic acid, phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine, dye = 2,2′-dipyridylamine, bpe = 1,2-bis(4-pyridy) ethane), were synthesized and structurally characterized by elemental analyses, plasma (ICP) spectrometry, IR spectroscopy, and single-crystal X-ray diffraction analyses. 1–3 are 1D ring chains. 4 shows a 2D bilayer network based on a tetranuclear cadmium cluster linked by (dppa)4− ligands. 5 displays a 2D bilayer network based on a trinuclear cadmium cluster, in which (dppa)4− ion shows two different coordination modes. In contrast to the above MOFs, 6 possesses a 3D network structure based on dinuclear cadmium units cross-linked by (dppa)4− and bpe ligands. For 1–6, weak hydrogen bonding and π⋯π stacking contacts link the discrete 1D chains or 2D networks to form high-dimensional supramolecular structures. Especially, in 1–6, (dppa)4− ligand displays seven different coordination modes and conformations, which may show natural synergy in the structural diversity of the resulting MOFs. The remarkable characteristic of these frameworks is that 2 demonstrates highly selective and sensitive bifunctional luminescent sensing towards acetone and Fe3+ ion. In addition, the thermal stabilities and luminescence properties of the MOFs were studied. [ABSTRACT FROM AUTHOR]

The beneficial effects of transmetalation on MOFs' functional behaviours are well-known as it endows the material with novel functionalities. Even though the structural adaptation of the framework to the new metal ion has a great impact on the properties of the resulting material, this subject still remains poorly understood. Herein, we present a detailed structural study by single crystal XRD and scanning electron microscopy on the unprecedented Co-substituted form of a renowned MOF, namely IRMOF-9. The performed Zn-to-Co exchange induced profound changes in the microstructure of the crystals as well as in the framework arrangement. While the evaluation of the first suggests an unconventional transmetalation mechanism involving a phase demolition and re-growth process, the average coordination network shows a remarkable shrinking of the solid with a loss of ∼2.5% of its starting volume. This deformation comes with an increased exposure of the metal sites to the MOF cavities due to a more open disposition of the linkers, whose peculiar disorder agrees with such structural change. These results shed light on the complexity of IRMOF-9(Co), highlighting the importance of structural investigations in transmetalation studies. [ABSTRACT FROM AUTHOR]

Solid-state X-ray scintillators are widely applied in medical imaging and space exploration. However, it is still a great challenge to probe into the intrinsic nature of scintillating behaviour due to the ambiguous structure–function relationship. Herein, four structure-defined X-ray scintillating Pb(ii)-based metal–organic frameworks (SMOFs) were successfully obtained under solvothermal conditions, [Pb(1,4-ndc)(DMF)]n (SMOF-1), [Pb(1,4-ndc)(DMA)]n (SMOF-2), [Pb2(2,6-ndc)2(H2O)]n·nDMF (SMOF-3) and [Pb4(2,6-ndc)3Cl2]n (SMOF-4), where 1,4-H2ndc = 1,4-naphthalene dicarboxylate, 2,6-H2ndc = 2,6-naphthalene dicarboxylate, DMF = N,N-dimethylformamide, and DMA = N,N-dimethylacetamide. SMOFs 1–4 show scintillating signals under X-rays triggered by a highly purified tungsten target. Compared with SMOFs 1–3, SMOF-4 exhibits excellent scintillating performance owing to its solvent-free and denser structure, which favours more efficient conversion ability of X-rays to visible light. X-ray stimulated luminescence (XSL) spectra present multiple emission peaks, which is further confirmed by wavelength-dependent luminescence spectra under UV-Vis light, and density of state and DFT calculations. The synergistic effects of heavy metal Pb(ii) centres as effective X-ray absorbers and organic ligands as luminescent motifs endow these Pb(ii)-based MOFs with application prospects in X-ray detection. [ABSTRACT FROM AUTHOR]

Two novel metal–organic frameworks [Ni2(μ2-Cl)(BTBA)2·DMF]·Cl·3DMF (JLU-MOF56, BTBA = 3,5-bis(triazol-1-yl)benzoic acid) and [Co2(μ2-Cl)(BTBA)2·DMF]·Cl·3DMF (JLU-MOF57) have been successfully synthesized under solvothermal conditions. Crystallographic analysis indicates that the two compounds with different metal ions are isoreticular and both are constructed from binuclear [M2(μ2-Cl)(COO)2N4] (M = Co, Ni) and a 3-connected hetero-N,O donor ligand. The overall framework possesses a (3,6)-connected dag topology. Furthermore, both of them feature ultramicroporous channels of 3.5 Å× 3.4 Å, which are suitable for adsorbing smaller carbon dioxide (CO2) gas molecules but not larger nitrogen (N2) gas molecules. Therefore, JLU-MOF56 and JLU-MOF57 exhibit good performance for CO2/N2 separation, and are promising materials for gas adsorption and purification. [ABSTRACT FROM AUTHOR]

A new 3D zinc–organic framework [Zn(QDA)]·0.5H2O·0.7DMF (1, H2QDA = quinoline-2,6-dicarboxylic acid, DMF = N,N-dimethylformamide) was synthesized under solvothermal conditions. The single crystal X-ray diffraction analysis reveals that the 3D framework structure of 1 has a PtS topology and contains Zn(ii) ions having distorted square pyramidal geometry with ZnO4N configuration. The phase purity of the bulk sample was characterized by X-ray powder diffraction (XRPD), thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy. The as-synthesized sample (1) was activated by stirring with acetone for 24 h, followed by heating under vacuum for 24 h at 120 °C. The TGA experiment indicated that both 1 and its activated form (1′) are stable up to 380 °C. The crystalline structure of the compound was retained after immersion in water, 1 M HCl, acetic acid and NaOH (at pH = 10) solutions. Compound 1′ exhibited very quick fluorescence quenching response after the addition of Fe3+ solution. This quenching was not affected by the presence of other competitive metal cations. A very low detection limit of 9.2 ppb was observed for Fe3+ ions, which is among the lowest values documented in the literature for MOF based fluorescent probes. Both fluorescence resonance energy transfer (FRET) and photo-induced electron transfer (PET) processes play major roles in the selective detection of Fe3+ ions. The recyclability experiment suggested that 1′ can be used for the long-term detection of Fe3+ ions. [ABSTRACT FROM AUTHOR]

The functionalization of the metal–organic framework MIL-47(VIV) with ligands bearing bulky functional groups (–Br or –CF3) has been envisaged as a possible route to enhance the mechanical energy storage performances of this family of hybrid porous materials. This exploratory work was carried out by coupling advanced experimental techniques (mercury intrusion and X-ray powder diffraction) supported by density functional theory calculations. MIL-47(VIV)-BDC-CF3 was demonstrated to be one of the most promising porous materials for mechanical energy-related applications with performance in terms of work energy which surpasses that of any porous solids reported so far. [ABSTRACT FROM AUTHOR]

Two new 2D MOFs, formulated as {[Cd(OBA)(L)]·DMF}n, 1 and {[Zn2(SDB)2(L)]·EtOH·3H2O·2DMF}n, 2 (L = 3-pyridinecarboxaldehyde nicotinoylhydrazone, H2OBA = 4,4′-oxybis(benzoic acid), H2SDB = 4,4′-sulfonyldibenzoic acid, DMF = N,N-dimethylformamide), have been synthesized at room temperature and characterized by elemental analyses (EA), FTIR spectra, single-crystal X-ray diffraction analyses (SCXRD), powder X-ray diffraction analyses (PXRD) and thermogravimetric analyses (TGA). The structural investigations reveal that both MOFs can be rationalized as a 4-c, uninodal net with sql topology. 1 and 2 are permanently microporous, having 1D channels with approximate sizes of 3.6 × 4.2 Å2 and 6.6 × 8.0 Å2, respectively. Furthermore, CO2, CH4 and N2 sorption studies are carried out in detail at varying temperatures, and the results show that the adsorption capacities of both 1 and 2 towards CO2 are higher than those towards CH4 and N2. Importantly, IAST calculations reveal that 1 and 2 display high separation selectivities for CO2/N2 (15 : 85) and CO2/CH4 (50 : 50) mixtures at ambient conditions. [ABSTRACT FROM AUTHOR]

Four novel Co(ii) metal–organic frameworks, namely [Co2(4,4′-cpmb)2(1,1′-bbi)2]n (1), [Co(4,4′-cpmb)(4,4′-bbibp)]n (2), {[Co(4,4′-cpmb)(tib)]·3(H2O)}n (3) and {[Co(4,4′-sdc)(tib)]·(H2O)}n (4) (flexible 4,4′-cpmb = 4-(4-carboxylphenylmethylthio)benzoic acid, rigid 4,4′-sdc = 4,4′-stilbenedicarboxylic acid, flexible 1,1′-bbi = 1,1′-(1,4-butanediyl)bis(imidazole), rigid 4,4′-bbibp = 4,4′-bis(benzoimidazo-1-ly)biphenyl and rigid tib = 1,3,5-tris(1-imidazolyl)benzene) were synthesized employing a rational design approach under solvothermal conditions and further characterized by elemental analysis, IR spectra, thermogravimetric (TG) analysis, powder X-ray diffraction (PXRD), and single-crystal X-ray diffraction. The four Co-MOFs display different interpenetrated structures due to the flexibility of O/N-donor ligands. Single-crystal X-ray diffraction analysis reveals that complex 1 displays a 6-fold interpenetrating class Ia net with the point Schläfli symbol of (66). Complex 2 shows a 3-fold interpenetrating sqc5 net with the point Schläfli symbol of (66·8). Complexes 3 and 4 exhibit a 2-fold interpenetrating 4-connected sql topology with the point Schläfli symbol of (44·62). The photodegradation properties and dye adsorption capacity of complexes 1–4 are investigated, and the framework integrity of complexes 1–4 can be well-retained. [ABSTRACT FROM AUTHOR]

We investigate the structural response of a dense peptide metal–organic framework using in situ powder and single-crystal X-ray diffraction under high-pressures. Crystals of Zn(GlyTyr)2 show a reversible compression by 13% in volume at 4 GPa that is facilitated by the ability of the peptidic linker to act as a flexible string for a cooperative response of the structure to strain. This structural transformation is controlled by changes to the conformation of the peptide, which enables a bond rearrangement in the coordination sphere of the metal and changes to the strength and directionality of the supramolecular interactions specific to the side chain groups in the dipeptide sequence. Compared to other structural transformations in Zn(ii) peptide MOFs, this behaviour is not affected by host/guest interactions and relies exclusively on the conformational flexibility of the peptide and its side chain chemistry. [ABSTRACT FROM AUTHOR]

High-pressure single-crystal X-ray diffraction was performed on dimethylammonium metal formates (DMAMF), [(CH3)2NH2][M(HCOO)3] where M = Mn2+, Fe2+, and Cu2+, in order to compare the high-pressure phases with the known low-temperature ferroelectric (for DMAMnF) and multiferroic (for DMAFeF) phases. The ambient phases of dimethylammonium metal formates were stable up to 5.53(8), 5.7(3), and 7.3(2) GPa for DMAMnF, DMACuF, and DMAFeF, respectively. At higher pressures, phase transitions occurred that were initiated by the structural distortions of the metal formate framework. The distortions are accompanied by loss of dynamic disorder of dimethylammonium (DMA) in the DMAMnF and DMAFeF compounds, resulting in an antiferroelectric arrangement of the DMA cations. For DMACuF, the Jahn–Teller distortion is reduced upon compression up to ∼3.5 GPa; the inability to continue reducing the Cu–O bonding distances beyond this pressure could be responsible for triggering a distortive transition of the copper formate framework at 5.5 GPa. In the case of DMAFeF, the experiment was in addition conducted with a penetrating pressure-transmitting medium (PTM) that resulted in a disorder–order transition of the DMA cation at lower pressures with p = 4.0(6) GPa due to the PTM inclusion. [ABSTRACT FROM AUTHOR]

Two novel isoreticular cadmium metal–organic frameworks (MOFs) with the framework formula of [Cd2(BPTC)(solvent)3] (H4BPTC = 3,3′,5,5′-biphenyltetracarboxylic acid) have been constructed under diverse reaction conditions and characterized by single crystal X-ray diffraction, PXRD, IR and TGA. The neutral 3D frameworks of 1 and 2 with one-dimensional (1D) rhombic channels exhibit both distinct uptake and good selectivity for cationic methylene blue (MB) dye molecules. The adsorption capacity and adsorption kinetic constant of 2 are greater than those of 1, showing the importance of porosity and pore size during the adsorption. Moreover, both MOFs show effective degradation of rhodamine B (RhB) and methyl orange (MO) dyes under UV light irradiation. [ABSTRACT FROM AUTHOR]

A systematic expansion of the well-known non-interpenetrated and robust MOF-11 was accomplished through a rediscovery of the ligand tetrakis(4-carboxyphenyl)adamantane (L). The combination of a rigid tetrahedral L and copper(ii) paddle-wheel secondary building unit (SBU) resulted in a stable non-interpenetrated metal–organic framework, UOF-1 (UOF = University of Otago framework), with the predicted PtS topology. This MOF exhibits permanent porosity, as established by X-ray diffraction (XRD) and gas adsorption studies. This low-density open framework possesses one open-metal site per Cu(ii) cation which could be accessed by employing appropriate activation techniques such as the use of supercritical CO2 (s-CO2) or dry CH2Cl2. CO2 gas displayed higher affinity towards activated UOF-1 than CH4 and N2 gases at room temperature and low pressure. UOF-1 displayed excellent selectivity for CO2 over N2 of 52 : 1 at practical operating conditions of 15 : 85 CO2 : N2 mixture at 273 K and 1 bar. [ABSTRACT FROM AUTHOR]

In this article, two new networks, namely, {[Co(L)]·0.5(CH3CN)·5(H2O)}n (HPU-5) and {[Mn2(L)2(H2O)2]·2(CH3OH)·3(H2O)·2(DMA)} (HPU-6) (H2L = (5-(3,5-di-pyridin-4-yl-[1,2,4]triazol-1-ylmethyl)-isophthalic acid)) with different-sized pores were constructed. The photogradation and adsorption of dyes by the two MOFs were studied in detail. The results showed that the dye removal efficiency of degradation was much higher than that of adsorption. Additionally, when the pores of MOFs were enlarged, the contribution of dye removal through adsorption was still relatively low. Our findings suggest that MOFs with high photocatalytic activities should be synthesized to enhance dye removal efficiency to the maximum. [ABSTRACT FROM AUTHOR]

A microporous MOF {[Zn(SDB)(L)0.5]·S}n (IITKGP-5) with a polar pore surface has been constructed by the combination of a V-shaped –SO2 functionalized organic linker (H2SDB = 4,4′-sulfonyldibenzoic acid) with an N-rich spacer (L = 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene), forming a network with sql(2,6L1) topology. IITKGP-5 is characterized by TGA, PXRD and single crystal X-ray diffraction. The framework exhibits lozenge-shaped channels of an approximate size of 4.2 × 5.6 Å2 along the crystallographic b axis with a potential solvent accessible volume of 26%. The activated IITKGP-5a revealed a CO2 uptake capacity of 56.4 and 49 cm3 g−1 at 273 K/1 atm and 295 K/1 atm, respectively. On the contrary, it takes up a much smaller amount of CH4 (17 cm3 g−1 at 273 K and 13.6 cm3 g−1 at 295 K) and N2 (5.5 cm3 g−1 at 273 K; 4 cm3 g−1 at 295 K) under 1 atm pressure exhibiting its potential for a highly selective adsorption of CO2 from flue gas as well as a landfill gas mixture. Based on the ideal adsorbed solution theory (IAST), a CO2/N2 selectivity of 435.5 and a CO2/CH4 selectivity of 151.6 have been realized at 273 K/100 kPa. The values at 295 K are 147.8 for CO2/N2 and 23.8 for CO2/CH4 gas mixtures under 100 kPa. In addition, this MOF nearly approaches the target values proposed for PSA and TSA processes for practical utility exhibiting its prospect for flue gas separation with a CO2 loading capacity of 2.04 mmol g−1. [ABSTRACT FROM AUTHOR]

Seven novel highly connected metal–organic frameworks (MOFs), formulated as [Co7(aobtc)3(bpy)2(μ3-OH)2(μ2-OH2)2(H2O)4]·4H2O (1), [Ni5(aobtc)2(bpy)2(μ3-OH)2(H2O)6]·4H2O (2), [Zn3(aobtc)2]·H2bpy·H2O (3), [Zn3(aobtc)2]·H2bpp·H2O (4), [Cd3(aobtc)2]·[Me2NH2]2·3H2O (5), [Co3(aobtc)2]·H2bpp·H2O (6) and [Mn3(aobtc)2]·H2bpy·2H2O (7) (H4aobtc = azoxybenzene-3,3′,5,5′-tetracarboxylic acid, bpy = 4,4′-bipyridine, bpp = 1,3-bis(4-pyridyl)propane) have been synthesized and characterized by elemental analyses, IR spectra, single-crystal X-ray diffraction, powder X-ray diffraction, and thermal analyses. Compound 1 is a 3D (4,4,14)-connected self-penetrating framework with (46)2(45·6)(430·526·631·74) topology based on hexanuclear clusters as 14-connected nodes. To our knowledge, compound 1 represents the highest connected self-penetrating topology presently known in the entangled system. Compound 2 displays a trinodal (4,4,10)-connected network with (46)(45·5)(410·518·612·75) topology based on tetranuclear clusters as 10-connected nodes. Compounds 3–7 exhibit (4,8)-connected flu nets based on trinuclear clusters as 8-connected nodes, and these five MOFs show similar structures but different pore volumes mainly associated with the change of the species of guest molecules. Structural analyses of 1–7 demonstrate that increasing the metal nuclearity is a practical method to obtain highly connected coordination networks based on metal clusters as nodes. In addition, the magnetic properties of 1, 2, 6, and 7 and the luminescence properties of compounds 3–5 have also been studied. [ABSTRACT FROM AUTHOR]

The synthesis of catalytically active metal–organic frameworks (MOFs) with copper(II) paddle-wheel clusters and urea–carboxylate linkers was achieved at room temperature in the presence of sulphate anions. The role of various anions in determining the MOF structure was analysed using X-ray diffraction. Structural analysis of the MOFs indicated that a two-fold interpenetrated rhombus grid (HI-101) was formed in the presence of sulphate anions, but a three-fold interpenetrated square grid network (HI-102) was obtained with nitrate and perchlorate anions. The experiment performed with various anions in the presence of sulphate anions also resulted in the formation of HI-101, indicating the selectivity of sulphate anions in the formation of the HI-101 framework. HI-101 proved to be an efficient catalyst for the cycloaddition of CO2 at room temperature, the oxidation of primary alcohols to aldehydes and the methanolysis of epoxides, but the other MOFs were not catalytically active. Thus, the size, charge and affinity of sulphate anions play an important role in generating a two-fold interpenetrated rhombus grid, which is crucial for catalytic reactions. This study shows that anion-templated synthesis could generate a versatile urea-based MOF catalyst for CO2 fixation and other reactions. [ABSTRACT FROM AUTHOR]

Design and synthesis of robust porous lanthanide-based metal–organic frameworks (Ln-MOFs) from flexible organic ligands is currently a formidable task to chemists. In this work, a porous Ln-MOF based on a flexible cyclotriphosphazene-functionalized organic ligand, hexakis(4-carboxylatephenoxy) cyclotriphosphazene, has been solvothermally synthesized. Single-crystal X-ray diffraction analyses show that the compound exhibits a three-dimensional structure built from rod-shaped secondary building units which are linked to each other through the organic ligands to form open frameworks with rectangular channels along the crystallographic a direction. Remarkably, although the flexible ligand was used, the Ln-MOF material after desolvation exhibited permanent porosity which has been established by various gas adsorption isotherms, displaying selective adsorption of C2 hydrocarbons over CH4 at room temperature. This work presents a rare example of a permanently porous Ln-MOF based on a flexible ligand exhibiting selective gas adsorption behaviours. [ABSTRACT FROM AUTHOR]

A series of highly crystalline, porous, zirconium-based metal–organic frameworks (Zr-MOFs) with different ligand functionalities and porosities were applied for catalytic transfer hydrogenation of ethyl levulinate (EL) to form γ-valerolactone (GVL), using isopropanol as a hydrogen donor. The roles of the ligand functionality and the metal center of the Zr-MOFs were identified and reaction parameters optimized, for selective production of GVL. The maximum yield of GVL (up to 92.7%) was achieved in 2 h at 200 °C with UiO-66(Zr). Interestingly, zirconium trimesate (MOF-808) emerged as the most suitable candidate, with the highest GVL formation rate (94.4 μmol g−1 min−1) among the catalysts tested at 130 °C. It was also found to be effective in conversion of EL to GVL in an open system using the solvent refluxing method. Both the catalysts (UiO-66(Zr) and MOF-808) were recycled at least five times under their specified reaction conditions without a notable change in catalytic activity and product selectivity. Fresh and recycled catalysts were characterized in detail using X-ray powder diffraction (XRD), N2 adsorption–desorption, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) in order to understand the stability and structural changes that occurred in the catalysts. Finally, a plausible reaction mechanism was presented on the basis of active sites present in catalysts confirmed by characterization results. [ABSTRACT FROM AUTHOR]

Two novel metal–organic frameworks, formulated as [Ni3(qptc)2(H2O)3]·3.5H2O·3Me2NH (1) and [Co3(qptc)2(H2O)4]·5H2O (2) (H4qptc = 1,1′:4′,1′′:4′′,1′′′-quaterphenyl-2,4,2′′′,4′′′-tetracarboxylic acid), have been hydrothermally constructed based on a rigid aromatic multicarboxylate ligand. The single-crystal X-ray diffraction analysis shows that complex 1 crystallizes in the triclinic crystal system with space group P1̅ and possesses a 4,8-connected 3D open framework including trinuclear nickel Ni3 SBUs, which belongs to an scu topology with the point symbols (416·612) and (44·62). Complex 2 belongs to the monoclinic crystal system with space group C2/c and exhibits a 3D framework containing Co3 SBUs, which is a flu topology with the point symbols (412·612·84) and (46). Furthermore, the variable-temperature magnetic susceptibilities of complexes 1 and 2 have been investigated. Both complexes show weak ferromagnetic coupling between metal ions estimated by using a linear trinuclear model for 1 in the range of 2–300 K and the PHI program for 2 in the range of 20–300 K taking the orbital contribution into consideration. [ABSTRACT FROM AUTHOR]

Four new metal–organic frameworks, namely, [CdNa(bci)(H2O)3]n (1), [CdK(bci)(H2O)3]n (2), [Cd(Hbci)(H2O)]n (3) and {[(H2en)0.5Cd(bci)]·2H2O}n (4) (H3bci = bis(2-carboxyethyl)isocyanurate, en = ethylenediamine), have been prepared from H3bci and Cd(NO3)2 in aqueous solution using different alkaline reagents, namely, NaOH, KOH, triethylamine and ethylenediamine, respectively, which were characterized by single-crystal X-ray diffraction analyses, infrared spectroscopy, elemental analysis and powder X-ray diffraction. Compounds 1 and 2 are 3D heterometallic frameworks, featuring a 3-nodal 3,3,6-connected T5 type topology and a new 3-nodal 3,4,7-connected topology, respectively; complex 3 is a 3D monometallic framework with a uninodal 4-connected cag topology, while compound 4 is a 2D double-layer structure with a 2-nodal 3,6-connected kgd topology, which is extended to form a 3D supramolecular architecture by hydrogen bonds. Moreover, four new coordination modes of the H3bci ligand were observed in complexes 1–4. The results indicate that the alkaline reagents play a crucial role in the diversity of the structures and coordination modes of the H3bci ligand. The luminescence properties and thermal stabilities of these compounds were further investigated. Unexpectedly, complex 4 shows strong luminescence emission of guest ethylenediamine molecules. [ABSTRACT FROM AUTHOR]

The neutral flexible viologen based ligand 1,1′-bis(4-carboxybenzyl)-4,4′-bipyridinium dibromide (H2LBr2) and its self-assembly with first-row transition metals in an aqueous media leads to the formation of nine new zwitterionic (ZW) MOF materials with the following compositions: {[CuBr(L)]·(OH)·7H2O}n (1); {[M4(L)6(OH2)12]·2Br·3(bdc)·33H2O}n with M = Mn (2), Co (3) and Ni (4), {[M(bdc)(L)1.5]·9H2O}n with M = Cd (5) and Zn (6); {[Cu2(3-pzc)2(L)(OH2)]·5H2O}n (7); {[ZnCl2(L)0.5]·0.33H2O}n (8) and [Pd(HL)(Br)2(NO2)2(OH2)2] (9) (bdc = 1,4-benzenedicarboxylate, pzc = 3-pyrazole carboxylate). These compounds were characterized by single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), infrared spectrometry (IR), elemental analyses, thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC). Interestingly, when the samples are exposed to UV irradiation, photochromic behavior is observed for the ligand only, whereas the ZW MOFs are found to be photochemically inert. The fundamental structural origin for this photo reactivity is discussed in detail, as well as an in-depth CSD analysis of important intra- and intermolecular parameters of L-based MOFs. [ABSTRACT FROM AUTHOR]

The structural behaviour under mechanical stimuli of two metal organic frameworks, UiO-66(Zr) and MIL-125(Ti) and their amino-functionalized derivatives has been investigated by high-pressure powder X-ray diffraction up to 3.5 GPa. All these solids showed a gradual pressure-induced reversible decrease of their crystallinity and UiO-66(Zr)_NH2 material has been revealed as one of the most resilient MOFs reported so far corresponding to a very high bulk modulus. The mechanical behaviors of these MOFs have been correlated to their chemical and geometric features including the metal–oxygen coordination number, the nature of the organic linker, the porosity as well as their crystal density. [ABSTRACT FROM AUTHOR]

The high pressure behaviour of a cubic dense inorganic–organic framework [DABCOH22+][K(ClO4)3] (DABCOH22+ = diazabicyclo[2.2.2]octane-1,4-diium) has been systematically studied via synchrotron X-ray powder diffraction, over the range of 0–3.12 GPa. The framework [DABCOH22+][K(ClO4)3] shows a more rigid response, with a bulk modulus of 30(1) GPa and an axial compressibility of 7.6(4) × 10−3 GPa−1, compared with ZIF-8 and the dense hybrid solar cell perovskite CH3NH3PbI3. Density functional theory calculations reveal that the structural change in [DABCOH22+][K(ClO4)3] is attributed to the contraction of the KO12 polyhedra, which consequently results in the rotation of the perchlorate linkers and synergistic movement of the DABCOH22+ guest. Further extensive theoretical calculations of full elastic tensors give full mapping of the Young's moduli, shear moduli and Poisson's ratios of [DABCOH22+][K(ClO4)3], which are in the range of 31.6–36.6, 12.3–14.6 GPa and 0.2–0.32, respectively. The Young's and shear moduli of [DABCOH22+][K(ClO4)3] are larger than those of cubic MOF-5, ZIF-8 and CH3NH3PbI3. In addition, the narrow range of Poisson's ratios in [DABCOH22+][K(ClO4)3] indicates its very isotropic nature in response to biaxial stress. [ABSTRACT FROM AUTHOR]

The previously reported anisotropic thermal expansion of a three-dimensional metal–organic framework (MOF) is examined by means of theoretical calculations. Inspection of the 100, 190, 280 and 370 K single crystal X-ray diffraction (SCD) structures indicated a concerted change in the coordination sphere of the zinc centre leading to elongation of the coordination helix in the crystallographic c direction (the Zn–O(H)–Zn angle expands), while the largely unaltered ligands (the Zn…L…Zn distance remains constant) are pulled closer together in the ab plane. This study develops and evaluates a mechanistic model at the DFT level of theory that reproduces the convergent expansion of the coordination helix of the material. The linear increase in energy calculated for extension of a model consisting of six zinc centres and truncated ligands compares favourably with results obtained from a periodic DFT evaluation of the SCD structures. It was also found that the anisotropic thermal expansion trend could be reproduced qualitatively by Molecular Dynamics (MD) simulations in the NPT ensemble. [ABSTRACT FROM AUTHOR]

The flexibility of eight aluminium hydroxo terephthalates [Al(OH)(BDC–X)]·n(guest) (BDC = 1,4-benzene-dicarboxylate; X = –H, –CH3, –Cl, –Br, –NH2, –NO2, –(OH)2, –CO2H) crystallising in the MIL-53-type structure was investigated upon thermal dehydration of as-made samples, superhydration and methanol adsorption/desorption using in situ powder X-ray diffraction (PXRD). Profile fitting was used to determine lattice parameters as a function of time and/or temperature to describe their structural evolution. It has thus been shown that while methanol vapour adsorption induces an opening of all the modified frameworks, except the –NH2 material, superhydration only leads to open structures for Al-MIL-53–NO2, –Br and –(OH)2. All the MIL-53 solids, except Al-MIL-53–(OH)2 are present in the open structures upon thermal dehydration. In addition to the exploration of the breathing behavior of this MIL-53 series, the issue of disorder in the distribution of the functional groups between the organic linkers was explored. As a typical illustration, density functional theory calculations were carried out on different structures of Al-MIL-53–Cl, in which the distribution of –Cl within two adjacent BDC linkers is varied. The results show that the most energetically stable configuration leads to the best agreement with the experimental PXRD pattern. This observation supports that the distribution of the selected linker substituent in the functionalised solid is governed by energetics and that there is a preference for an ordering of this arrangement. [ABSTRACT FROM AUTHOR]

The assembly of distinct 3d metal ions with triangular 1,3,5-benzenetricarboxylic acid (H3BTC) generates three new metal–organic frameworks, namely {[Co3Na(BTC)2(μ3-OH)(H2O)3(DMAc)]·H2O·0.5DMAc}n (1), {[Ni3(BTC)2(μ3-OH)(H2O)3]·2H2O·DMAc}n (2) and {[NH2(CH3)2]2[Mn3(BTC)2(CH3COO)2]·DMAc}n (3) (DMAc = N,N′-dimethylacetamide). Complexes 1 and 2 show Co3/Ni3 cluster based three-dimensional (3D) frameworks with (3,7)-connected new topology and (3,6)-connected sit topology, respectively, while complex 3 reveals a 3D framework composed of one-dimensional rod-shaped sinusoidal-like MnII-chains. Magnetic investigation shows that 1–3 display antiferromagnetic behaviors although they feature different spin carriers and linkage modes of spin carriers. [ABSTRACT FROM AUTHOR]

Solvothermal reactions of Co2+ and Mn2+ salts with 2-(trifluoromethyl)-1H-4,5-imidazole dicarboxylic acid (H3TFMIDC) lead to two novel three-dimensional (3D) metal–organic frameworks (MOFs), namely, [Co6(μ3-TFMIDC)4(H2O)12]·15H2O (1) and [(Me2NH2)3][MnII6 MnIII(μ3-TFMIDC)6(H2O)6]·18H2O (2). Single-crystal X-ray diffraction analysis reveals that both of them are based on interesting planar tetranuclear squares [M4(TFMIDC)4] as secondary building units (SBUs). Compound 1 exhibits a unique 3D two-fold interpenetrated network with the diamondoid topology consisting of the tetranuclear square SBUs as 4-connected nodes, while compound 2 features an unusual (6,16)-connected 3D framework based on the novel tetranuclear square SBUs as 16-connected nodes and trivalent manganese ions as 6-connected nodes, representing the first 16-connected MOF utilizing planar tetranuclear square SBUs as building blocks. Our results open up new perspectives to design novel 3D extended MOFs, especially the unique highly connected 3D MOFs by employing planar tetranuclear square SBUs. Moreover, IR spectroscopy, powder X-ray diffraction, thermogravimetric analyses, and a study on the magnetic properties of both compounds, have been also performed. [ABSTRACT FROM AUTHOR]

A solvothermal reaction of Zn(ii) salt with methanetetrabenzoic acid (H4MTB) and 1,4,8,11-tetraazacyclotetradecane (cyclam, CYC) created a new microporous metal–organic framework {[Zn2(μ4-MTB)(κ4-CYC)2]·2DMF·7H2O}n (DMF = N,N′-dimethylformamide). Single crystal X-ray diffraction showed that the complex exhibits a four-fold interpenetrated diamond-like structure topology with 1D jar-like channels with sizes about 14.1 × 14.1 and 2.4 × 2.4 Å2. The stability of the framework and activation conditions of the compound have been studied by high-energy powder X-ray diffraction during in situ heating, thermogravimetric analysis coupled with mass spectrometry and infrared spectroscopy performed at different temperatures. The gas adsorption behaviour of {[Zn2(μ4-MTB)(κ4-CYC)2]·2DMF·7H2O}n was studied by adsorption of Ar, N2, CO2 and H2. Nitrogen and argon adsorption showed that the activated sample exhibits Brunauer–Emmet–Teller (BET) specific surface areas of 644 m2 g−1 (N2) and 562 m2 g−1 (Ar). The complex adsorbs carbon dioxide with a maximum storage capacity of 10.5 wt% at 273 K and 101 kPa. The observed hydrogen uptake was 1.27 wt% at 77 K and 800 Torr, which is the highest value reported for the compounds containing a MTB4− linker. The adsorption heats of carbon dioxide and hydrogen, calculated according to the Clausius–Clapeyron equation, were in the range 22.8–22.4 kJ mol−1 for CO2 and 8.9–3.2 kJ mol−1 for H2, indicating weak interactions of the gases with the framework. [ABSTRACT FROM AUTHOR]

Mixing transition metal(ii) salts with 3,3′-diphenyldicarboxylic acid (3,3′-H2dpdc) and 1,3-bis(4-pyridyl)propane (bpp) led to the complexes [M(3,3′-dpdc)bpp] (M = Zn 1, Cd 2) and [Cu2(3,3′-dpdc)2(bpp)] (3). These complexes were characterized by single-crystal X-ray diffraction. 1 possesses a four-fold interpenetrating 3D diamondoid framework consisting of Zn-3,3′-dpdc and Zn-3,3′-dpdc-bpp helices and has a 66 topology net with 4-c tetrahedral Zn(ii) nodes. 2 exhibits a 3D framework consisting of Cd-3,3′-dpdc-bpp two/four-stranded helices and has a 6-c {36·412·54·66} topology with binuclear blocks. 3 has a three-fold interpenetrating 3D framework with a 6-c {312·428·55} topology based on binuclear blocks. Cu-3,3′-dpdc and Cu-bpp-3,3′-dpdc helices are formed. The metal centers play a crucial role in the system structure direction. The luminescence properties of these compounds were investigated. The results show that 1 can be used as a fluorescent probe to detect benzaldehyde and sensitize Tb(iii) luminescence. Notably, addition of Tb(iii) into the Zn-MOF (1) greatly enhanced its ability to detect benzaldehyde. [ABSTRACT FROM AUTHOR]

A heterometallic coordination polymer {[Cu(bpy)3][Mn2(C2O4)3]·H2O}n (1; bpy = 2,2′-bipyridine) was synthesized using a building-block approach and characterized by IR spectroscopy, single-crystal X-ray diffraction, magnetization measurement, and X-band ESR spectroscopy both on a single crystal and a polycrystalline sample. The molecular structure of 1 is made of a three-dimensional (3D) anionic network [Mn2(C2O4)3]n2n− and tris-chelated cations [Cu(bpy)3]2+ occupying the vacancies of the framework. In compound 1 magnetic order is confirmed below 12.8 K – magnetization measurements reveal an antiferromagnetic-like network of canted Mn2+ spins with incorporated paramagnetic Cu2+ centres. The ESR spectroscopy distinctly shows the phase transition; above T≈ 13 K, single isotropic Lorentzian lines of Mn2+ ions in the high spin state S = 5/2 were observed, while below this temperature, only characteristic Cu2+ signals from cations were detected. Thermal decomposition residues of 1 at different temperatures (800–1000 °C) were analyzed by powder X-ray diffraction; by heating the sample up to 1000 °C the spinel oxide CuMn2O4 [94.1(2) wt%] was formed. From the refined structural parameters, it could be seen that the obtained spinel is characterized by the inversion parameter δ∼ 0.8, and therefore the structural formula at room temperature can be written as tet[Cu0.17Mn0.83]oct[Mn1.17Cu0.83]O4. [ABSTRACT FROM AUTHOR]

A series of isostructual aromatics⊂CdL2(OTs)2 (aromatics = benzene, toluene, o-xylene, m-xylene and p-xylene) supramolecular complexes were prepared based on aromatic templates. The CdL2(OTs)2 framework is stable and contains square-like hydrophobic channels. It can reversibly adsorb benzene, toluene, o-xylene, m-xylene and p-xylene in the liquid phase without the loss of its structural integrity. Furthermore, it exhibits a clear affinity for these aromatics according to the following order: xylene ＞ toluene ＞ benzene, and it effectively separates xylene/toluene/benzene mixtures in the liquid phase under ambient conditions. In addition, aromatics⊂CdL2(OTs)2 exhibits guest-dependent luminescence properties. [ABSTRACT FROM AUTHOR]

Solvothermal reaction of a TCA (TCA = 4,4′,4′′-tricarboxytriphenylamine) ligand with Cd(NO3)2 yielded a unique 3D 12-connected metal–organic framework of 1, which can be simplified as a (3,3,12)-connected 3-nodal net with a Schläfli symbol of {416·636·814}{42·6}2{43}2 based on a 12-connected node of a pentanuclear Cd(ii) cluster and a three-connected organic linker of TCA. Compound 1 exhibits both photoluminescence and proton conductivity. The luminescence properties of 1 originate from the triphenylamine chromophore of the TCA ligand. The proton conductivity of 1 is supposed to be relevant to the structure attributes of 1. On the one hand, the curved narrow channels lined with a hydrophilic pentanuclear Cd(ii) cluster in 1 can improve the water affinity of framework and facilitate the water absorption under humid conditions. On the other hand, the coordinated water molecules within the pentanuclear Cd(ii) cluster can produce a mobile H+ proton due to coordination activation. At 80 °C and 85% RH (relative humidity), compound 1 shows the proton conductivity of 1.45 × 10−6 S cm−1. [ABSTRACT FROM AUTHOR]

A new three-dimensional NbO-type porous metal–organic framework ZJNU-47 was synthesized via a solvothermal reaction of Cu(NO3)2·3H2O and a Lewis basic nitrogen donor site-rich tetracarboxylate, namely, 5,5′-(pyridazine-3,6-diyl)-diisophthalate, and the structure was characterized by single-crystal X-ray diffraction to be isostructural with NOTT-101. With the synergistic effect of open metal sites, Lewis basic sites and a suitable pore space, the MOF material ZJNU-47a after activation can take up a large amount of C2H2 and CO2. The gravimetric C2H2 uptake of 214 cm3 (STP) g−1 at room temperature and 1 atm is the highest among all reported MOFs to date, and the gravimetric CO2 uptake of 108 cm3 (STP) g−1 is also among the highest reported for MOFs. Compared to the isostructural MOF NOTT-101a, ZJNU-47a exhibits a significant increase in C2H2 and CO2 uptake and thus improved C2H2/CH4 and CO2/CH4 separations. Significantly, comprehensive DFT studies of C2H2 and CO2 adsorption have revealed that the open nitrogen donor sites are comparable and even superior to open metal sites regarding the adsorption sites. This work demonstrated that the simultaneous introduction of Lewis basic nitrogen donor sites and Lewis acidic metal sites into the framework is a promising approach to improve the gas sorption toward CO2 and C2H2 and thus to produce materials possessing enhanced C2H2/CH4 and CO2/CH4 separation performance. [ABSTRACT FROM AUTHOR]

The butterfly-like tetranuclear cobalt cluster based 3D MOF [Me2NH2][Co2(bptc)(μ3-OH)(H2O)2] (1) underwent a reversible thermally triggered single-crystal-to-single-crystal transformation via Co–Owater weakened intermediate 1a to produce a partly dehydrated phase [Me2NH2][Co2(bptc)(μ3-OH)(H2O)] (2), which was confirmed by single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis, and IR spectroscopy. During the dehydration course, the local coordination environment of one Co2+ ion was changed from the saturated octahedron to a coordinately unsaturated square-pyramid, accompanied by a crystal color change from red to purple. Compared with pristine hydrated 1, dehydrated 2 exhibits highly efficient and recyclable catalytic activity for cyanosilylation of carbonyl compounds with a low catalyst loading of 0.1 mol% Co at room temperature under solvent-free conditions, which due to the open Co2+ sites as catalytically activated sites played a significant role in the heterogeneous catalytic process. [ABSTRACT FROM AUTHOR]

Two series of new lanthanide coordination polymers have been obtained by solvothermal reaction of Ln(NO3)3 and pamoic acid under different pH values. Both series of compounds show three-dimensional porous frameworks composed of dinuclear Ln(iii) subunits. Series B demonstrates fascinating solvent-induced dynamic behaviors in an SCSC (single crystal to single crystal) manner. The capability of activated series B to absorb liquid acetone was investigated by means of 1H NMR spectroscopy, demonstrating the potential of Ln-MOFs as highly efficient and reusable liquid acetone sorbents. In addition, photoluminescence properties of Nd (3), Eu (5) and Yb (10) were measured and discussed. Lanthanide contraction effect also played a crucial role in the formation of each series of complexes. Analysis of the relations between the ionic radius (Ln3+) and the number of f electrons in these complexes indicates that lanthanide contraction effect in both series can be well described by the Raymond model. [ABSTRACT FROM AUTHOR]