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The combination of electron-deficient viologen ligands with electron-rich POMs is a typical acceptor–donor system that has recently received much attention. Under solvothermal and hydrothermal conditions, by introducing three symmetric viologen ligands into POM-based hybrid materials, we successfully constructed four POMs–viologen inorganic–organic hybrid compounds, namely (1,3-bcbpy)2·(δ-Mo8O26) (1) (1,3-bcbpy·2Cl = 1,1′-bis(3-carboxybenzyl)-4,4′-bipyridine dichloride), {CoII(1,4-bcbpy)2(H2O)2[H2(β-Mo8O26)]}·2H2O·2CH2O (2), (1,4-bcbpy)2·(δ-Mo8O26)·2H2O (3) (1,4-bcbpy·2Cl = 1,1′-bis(4-carboxybenzyl)-4,4′-bipyridine dichloride, CH2O = formaldehyde), and {CuII(1,1-pmbby)2(H2O)[H2(β-Mo8O26)2]}·5H2O·C2H7N (4) (1,1-pmbby·2Cl = 1,1′-[1,4-phenylbis(methylene)]bis-(4,4′-bipyridine)dichloride, C2H7N = dimethylamine). These four compounds exhibit different fascinating structures, especially compound 4 is a typical metal–organic framework. Compounds 1–4 exhibit good discoloration behaviors under various external stimuli. For example, compounds 1–4 showed a positive response to the irradiation from a 300 W Xe lamp. When a positive voltage was applied to the ECD based on compounds 1–4, 1/2/3/4-ECD underwent a significant color conversion. What's more, compound 4 also showed obvious discoloration results after heating. In a word, 1–4 are multifunctional discoloration materials under different external stimuli. In addition, the coated filter paper prepared based on compound 3 can be used as a new printing material medium and can be successfully applied in erasable inkless printing and dual anti-counterfeiting. [ABSTRACT FROM AUTHOR]

A new magnesium-based metal–organic framework with unprecedented short-chain secondary building units and ultra-micropore channels approaching the kinetic diameters of Xe is fabricated by decorating methyl groups on ligands. Due to the contracted pores, this MOF exhibits very high selectivity values for Xe/Kr, which ranks it among the top porous absorbents. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have garnered significant interest owing to their tunable structures and versatile properties. In this study, the construction of MOF-74 analogues based on pre-installation of functional ligands has been investigated. Five distinct ligands and their corresponding complexes are synthesized and characterized. The ligands are strategically designed to impart specific functional groups, enabling enhanced reactivity and tailored properties. Building upon the previously synthesized compounds, an efficient method for the directional functionalization of MOF-74 analogues under moderate conditions has been outlined. This method involves pre-installation through directive substitution of the ligands with suitable functional groups viz. –F, –Br, –I, –CH3 and –CN, allowing precise control over the resulting MOF's properties and functionalities. The study presents the characteristics and properties of [Cu(L1)]n (1), [Cu(L3)]n (2), [Cu(L4)]n (3), [Cu(L5)]n (4) and [Cu(L6)]n (5) complexes, highlighting their distinct features and potential applications. The findings from this research contribute to the fundamental understanding of MOF-74 analogues' synthesis and the efficient functionalization of these materials. The outlined methodology opens new avenues for the tailored design of MOFs with desired properties, enabling their potential utilization in diverse applications, such as catalysis, gas storage and luminescence sensing properties. [ABSTRACT FROM AUTHOR]

A new three-dimensional (3D) framework with the general formula {[Cu(μ3-dmg)(im)2]·3H2O}n (1) was synthesized using an aliphatic dicarboxylic acid linker 2,2-dimethylglutarate (dmg2−) and nitrogen-containing imidazole ligand (im) under conventional methods. 1 was characterized by FT-IR spectroscopy, elemental analysis, single crystal and powder X-ray diffractions, and thermal analysis techniques. Additionally, the optical and topological properties of compound 1 were also investigated. The single crystal X-ray data exhibit that 1 is an interesting 3D framework and it has a I41/a space group, which originates from two imidazole ligands, one dmg and three lattice water molecules. Topologically, 1 displays a lvt-a topology with the point symbol of {4.8.10}. In addition, the catalytic activity of compound 1 was investigated in the CO2 conversion into cyclic carbonates. It was found that compound 1 was an active catalyst even at low catalyst loading under 0.1 MPa CO2 at 80 °C. The yields of 23–99% were obtained. Compound 1 can be recycled at least four times without significant compromise in the activity in the first three catalytic reactions. [ABSTRACT FROM AUTHOR]

Two organic ligands, one rigid and one flexible, were designed and used to construct two cobalt-based metal–organic frameworks (MOFs) with coligands to obtain 3D and 2D structures, respectively. Both the Co-based MOFs were pyrolyzed at different temperatures to obtain the derived materials, and their electrocatalytic hydrogen evolution properties were studied. The results show that the electrocatalytic hydrogen evolution performance of MOF derivatives based on the rigid ligand was better than that of MOF derivatives based on the flexible organic ligand. [ABSTRACT FROM AUTHOR]

Non-heme mononuclear iron complexes, especially when supported by tripodal tetradentate ligands, show promising C–H bond activation efficiency in catalytic reactions. Nevertheless, they intrinsically decay readily to their dinuclear form, and the dimerization process is inevitable in homogenous solution, which dramatically hinders their further application. Hence, we demonstrate that the mononuclear iron complex [(TPA)FeII-2L]2+ (L = labile ligands, mainly solvent molecules) was successfully encapsulated in a highly robust metal–organic framework UiO-66 via a two-step "ship-in-a-bottle" strategy. The nearly perfect size matching of the octahedral cages of the host UiO-66 provides ideal space confinement for the guest complex to protect from dimerization and dramatically increases the mono-nuclear complex stability compared to its un-confined state. The successful encapsulation of [(TPA)FeII-2L]2+ in UiO-66 was verified thoroughly by spectroscopy, microscopy, N2 adsorption, and electrochemistry characterization techniques. This work shows that encapsulating an unstable molecular complex in MOFs via a two-step "ship-in-a-bottle" strategy highlights opportunities for extending the heterogenization of homogeneous complexes. [ABSTRACT FROM AUTHOR]

Energetic metal organic frameworks (EMOFs) are increasingly developed and have proven to be candidates for novel high energy density materials (HEDM). Here, two energetic metal complexes based on 3,5-diaminopyrazolone-4-oxime (DAPO) ligands were synthesized by simple steps and fully characterized by NMR and IR spectroscopy, X-ray single-crystal diffraction, and DSC-TG. The detonation performance was calculated using the Kamlet–Jacobs formula. The crystal densities of these complexes (C6H14N12O10Co (2) and C6H14N12O10Cd (3) are as high as 1.945 g cm−3 at 163 K and 2.072 g cm−3 at 298 K, respectively. Thermal analysis by the DSC-TG test shows that they all have good thermal stability with the highest decomposition temperatures of 287 °C and 344 °C, respectively. These two as-synthesized complexes exhibit excellent detonation performance; 2 (D = 8682 m s−1, P = 34.98 GPa) and 3 (D = 8383 m s−1, P = 33.78 GPa) have good detonation velocity and detonation pressure that are superior to those of TNT, which is widely used today. Thus, they show great promise for potential applications as thermally stable energetic materials. [ABSTRACT FROM AUTHOR]

The spinel LiMn2O4 cathode has received substantial attention from researchers owing to its high voltage plateau, eco-friendliness, and cost-effectiveness. Nevertheless, its practical application has been impeded by severe capacity attenuation due to the Jahn–Teller effect and spontaneous disproportionation reaction. To overcome these issues, this study synthesized a series of manganese-based metal–organic frameworks with varying structures using aromatic carboxylic acids that contain different numbers of carboxyl groups as organic frameworks. These frameworks were then used as precursors for synthesizing spinel LiMn2O4 cathode materials. This approach aims to enhance capacity, cycle stability, and rate performance by reducing the diffusion resistance of lithium ions, exposing the (111) plane, and increasing the Mn3+ content. The LMO-PMA sample exhibited remarkable cycling stability (91.4% after 1000 cycles at 10C) and superior capacity (140.2 mA h g−1 at 0.2C, 113.1 mA h g−1 at 10C). This approach can be extended to the synthesis of other cathode materials. [ABSTRACT FROM AUTHOR]

Stability is a key factor that restricts the practical applications of metal–organic framework (MOF) materials. In this work, we report an ultrastable three-dimensional cage-like MOF, SrCu(HC3N3O3)2, constructed by a polydentate cyanurate ligand and two kinds of different metal nodes. A high ratio of coordination sites in organic ligands, specific coordination of strong acid with a strong base and weak acid with a weak base and double independent completed coordination networks endow SrCu(HC3N3O3)2 with outstanding thermal stability (up to 300 °C) and acid/alkali resistance (pH = 2–14). Moreover, SrCu(HC3N3O3)2 possesses the highest porosity up to 36.7% among cyanuric acid-based MOF materials and exhibits differentiated adsorption of C3H4 (63 cm3 g−1) and C3H6 (51 cm3 g−1). The breakthrough experiment further verified that efficient C3H4/C3H6 separation can be achieved under dynamic conditions by SrCu(HC3N3O3)2. [ABSTRACT FROM AUTHOR]

A new rigid bipyridinyl-derived ligand has been utilized for the fabrication of two metal–organic frameworks, denoted as [M(L)(mipa)]n [M = Zn (1) and Cd (2), L = 2,6-bis((E)-4-(pyridine-3-yl)benzylidene)cyclohexanone, H2mipa = 5-methylisophthelic acid], through solvothermal synthesis by using a mixed-ligand strategy. Structural analysis reveals that these isomorphic compounds display a 3,5-connected two-dimensional network with an unprecedented (42·67·8)(42·6) topology. Both of them exhibit certain chemical stability and thermal stability. Notably, the photocatalytic properties of the two compounds for the degradation of several organic dyes have been explored. [ABSTRACT FROM AUTHOR]

Four novel Zn(ii) metal–organic frameworks (MOFs) including {[Zn(L)0.5(bimb)]·2H2O·0.5(CH3)2NH}n (1), {[Zn(L)0.5(bimmb)]·2H2O}n (2), {[Zn(L)0.5(btdpe)]·H2O}n (3), and [Zn(L)0.5(bidpe)]n (4) (H4L = 5,5′-(1,4-xylylenediamino) diisophthalic acid, bimb = 1,4-bis(imidazol-1-yl)-butane, bimmb = 1,4-bis(imidazol-1-ylmethyl)benzene, btdpe = 4,4′-bis(4H-1,2,4-triazol-4-yl)diphenyl ether, and bidpe = 4,4′-bis(imidazolyl)diphenyl ether) were solvothermally prepared and further characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction, thermogravimetric (TG) analysis and powder X-ray diffraction (PXRD). Single-crystal X-ray diffraction analysis showed that complex 1 features a 3-fold interpenetrated bbf topological framework with the Schläfli symbol of (64·82)(66)2. Complex 2 displayed an unprecedented 2-nodal (4,4)-connected 3D framework with the Schläfli symbol of (86), while complexes 3 and 4 showed 3-nodal (2,4,4)-connected (4·8·104)2(4)2(84·10·12)-unprecedented frameworks. Luminescence studies revealed that complexes 1–4 can be used as high selectivity luminescence sensors for sensing Fe(iii) cations, Cr(vi) anions (Cr2O72− and CrO42−) and nitroaromatic compounds. Furthermore, a possible sensing mechanism was investigated in this paper. [ABSTRACT FROM AUTHOR]

In this work, a series of butterfly-like isomers named oxacalix[2]naphthalene[2]pyrazine (ONP) were conveniently synthesized by a one-step catalyst-free reaction in a facile manner, and they exhibit typical characteristics of aggregation-induced emission (AIE). The mechanism study shows that restriction of intramolecular vibration (RIV) is the reason for their AIE properties. The pyrazine groups endow ONP molecules with good coordination ability, which makes them ideal ligands for constructing metal–organic frameworks (MOFs). Thus, three ONP-based luminescent MOFs were constructed, and they exhibit intense emission with lifetimes in the order of microseconds. More importantly, different ONP isomers have different binding capacities, and thus only one kind of MOF can be obtained even when using an isomer mixture of ONP ligands. This result suggested that the conformation of ONPs is an important determining factor for their application as bridging ligands. This work not only reports a series of new RIV-type AIEgens, but also offers a new platform for the construction of luminescent MOFs. [ABSTRACT FROM AUTHOR]

A palladium diphosphine pincer complex H3(PNNNP-PdI) has been encapsulated in the benzotriazolate metal-organic framework MFU-4l-OH ([Zn5(OH)4(btdd)3], btdd2− = bis(1,2,3-triazolo)dibenzodioxin), and the resulting materials were investigated as Lewis acid catalysts for cyclization of citronellal to isopulegol. Rapid catalyst immobilization is facilitated by a Brønsted acid–base reaction between the H3(PNNNP-PdI) benzoic acid substituents and Zn–OH groups at the framework nodes. Catalyst loading can be controlled up to a maximum of 0.5 pincer complexes per formula unit [ PdI-x , Zn5(OH)4−nx(btdd)3(H3−nPNNNP-PdI)xx = 0.06–0.5, n ≈ 2.75]. Oxidative ligand exchange was used to replace I− with weakly coordinating BF4− anions at the Pd–I sites, generating the activated PdBF4-x catalysts (x = 0.06, 0.10, 0.18, 0.40). The Lewis acid catalytic activity of the PdBF4-x series decreases with increasing catalyst density as a result of the appearance of mass transport limitations. Initial catalytic rates show that the activity of PdBF4-0.06 approaches the intrinsic activity of a homogeneous PNNNP-PdBF4 catalyst analogue. In addition, PdBF4-0.06 exhibits better catalytic activity than the metallolinker-based MOF Zr-PdBF4 and was not subject to leaching or catalyst degradation processes observed for the homogeneous analogue. [ABSTRACT FROM AUTHOR]

A pair of chiral metal–organic frameworks based on enantiomers of chiral Zn(salen) ligands has been successfully obtained by solvothermal subcomponent self-assembly. Both chiral MOFs were characterized by infrared spectroscopy, UV-vis absorption spectroscopy, thermogravimetric analysis, and single-crystal/powder X-ray diffraction. They crystallize in the chiral space group I222 and possess an extended 2D network with a sql topology. Moreover, these MOFs exhibit circularly polarized luminescence (CPL) with a dissymmetry factor of about 3.7 × 10−3. This work provides a simple strategy to make CPL-active MOF materials based on salen ligands. [ABSTRACT FROM AUTHOR]

The design of metal–organic frameworks (MOFs) with high connectivity ligands is a potentially important approach towards enhanced stability materials and presents a powerful incentive in the self-assembly process towards high dimensionality networks, yet the MOF literature is dominated by di- and tri-carboxylate ligands. Herein, we report a new class of tetra-isophthalate "hyper-carboxylate" ligands containing flexible, linear diamine cores (H8L1, containing 1,2-diaminoethane; H8L2, 1,3-diaminopropane; H8L3, 1,4-diaminobutane; H8L4, trans-1,4-diaminocyclohexane). A series of MOFs based around copper(II) paddlewheel SBUs and these ligands has been found to regularly display cage-type cavities, not uncommon in isophthalate systems, that increase in size with longer diamine cores. However, with great flexibility comes great unpredictability, and a number of concomitant products were obtained in several instances. Notably the ligands, whilst all notionally able to connect to eight or more metal ions, are able to adopt a variety of coordination modes (coordinated to 8, 10, 12, or 14 metal ions) and topological connectivities (4-, 6-, and 8-connecting) as a consequence of their variable protonation states, in many instances leaving carboxylic acids directed into the framework channels. A variety of networks with other transition metals and node topologies further emphasise the unpredictability that can arise from having eight carboxylate groups in a single ligand including, somewhat surprisingly, two-dimensional coordination polymers. However, it is clear that despite the large variety of possible coordination modes leading to synthetic challenges in obtaining pure products, the use of highly decorated ligands is a strategy that generally trends towards three-dimensional networks of high connectivity. [ABSTRACT FROM AUTHOR]

Polyoxometalates (POMs) can participate into metal–organic frameworks to construct POM-based metal–organic frameworks (POMOFs) with excellent redox properties, displaying potential photo- and electrochemical applications. Here, two POMOFs [M2(btbu)4(H2O)2(SiW12O40)] [M = Ni for CUST-631 and Co for CUST-632; btbu = 1,4-bis(1,2,4-triazole-1-yl)butane] were synthesized by a hydrothermal method and characterized by PXRD, IR and TG. CUST-631 and CUST-632 are directly prepared as electrode materials (denoted as 631-CPE and 632-CPE) to explore their electrocatalytic properties. The experimental results show that 631-CPE and 632-CPE exhibit good electrocatalytic reduction of BrO3− and NO2− ions and great oxidation properties towards AA. [ABSTRACT FROM AUTHOR]

Two flexible ligands, 4,4′,4′′-(nitrilotris(methylene))tribenzoic acid (H3TCBA) and 1,4-bis((1H-imidazol-1-yl)methyl)benzene (BMB) have been used to construct a three-dimensional MOF with Co(NO3)2·6H2O through solvothermal techniques. The MOF is formulated as {[Co3(TCBA)2·BMB]·3DMF·8H2O}n (1). Topological analysis reveals that 1 is a 3,8-connected new net with point symbol {42·6}2{44·610·79·85}. The MOF has been characterized by single crystal X-ray diffraction, infrared spectroscopy (IR), thermogravimetry analysis (TGA), elemental analysis, UV-visible spectrum, X-ray powder diffraction (XRD), variable-temperature X-ray powder diffraction (VXRD). In addition, selective gas adsorption and magnetic properties of 1 have been explored. [ABSTRACT FROM AUTHOR]

The formation of coordination complexes, including metal–organic frameworks, occurs following the order of coordinating ability, which is the order of preference for molecules or ions to coordinate to a specific metal. The coordinating ability helps to predict and understand the resulting structures when it provides an absolute rule. Unfortunately, it frequently fails to follow a fixed order due to various environmental reaction parameters. We show that the conventional coordinating ability to yttrium becomes non-applicable in a H2O-rich solvent environment, resulting in compounds with the same structure from Y(NO3)3 and YCl3 precursors, while the order works well in a DMF-rich environment to give two compounds with different structures from Y(NO3)3 and YCl3 precursors. As a result, overall, three different yttrium-based MOF structures have been newly obtained from a single metal and ligand set, i.e., Y(III) and muconic acid through controlling the coordinating abilities of Y(III) via simply modulating the solvent environment: [Y(muco)1.5(H2O)] (1), [Y(muco)1.5(DMF)] (2), and [Y(muco)1.5(H2O)2]·2DMF (3). Our findings provide insight into the influence of the solvent environment on the role of the coordinating ability for the formation of yttrium coordination compounds and Y-MOFs with diverse structures. [ABSTRACT FROM AUTHOR]

Selective detection of antibiotics and MnO4− is crucial for human health improvement and protecting the environment. Two stable Zn(II)-based metal–organic frameworks (MOFs) {[Zn6(L1)2(NDC)5(μ2-OH)2]·0.5H2O}n (1), and {[Zn(L2)(NDC)]·2H2O}n (2) (H2NDC = 1,4-naphthalenedicarboxylic acid, L1 = 1,5-bis(1-(pyridine-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)pentane, L2 = 1,6-bis(1-(pyridine-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)hexane) were successfully synthesized by adopting the mixed ligands approach. 1 is a rare 3D 3,5,6T23 framework based polynuclear complex group. 2 possesses a 2D sql layer. The two MOFs exhibit excellent chemical and thermal stability. The title compounds are promising dual-functional fluorescent sensors for detecting enrofloxacin/MnO4− anions with high selectivity and sensitivity (Ksv values toward enrofloxacin: 4.29 × 106 L mol−1 for 1 and 4.59 × 106 L mol−1 for 2 and toward MnO4−: 1.05 × 104 for 1, 5.48 × 103 L mol−1 for 2, respectively), which are the first observations of fluorescent MOFs for the sensing of enrofloxacin and MnO4− anions. [ABSTRACT FROM AUTHOR]

Two new metal–organic frameworks (MOFs) with copper(II) paddlewheel secondary building units are presented. Cu-MOF and Pd@Cu-MOF were prepared in open air at room temperature from a pincer ligand 4,4′-((pyridine-2,6-dicarbonyl)bis(azanediyl))dibenzoic acid (L1) and a pincer complex NCONCON–Pd(II) (C1), respectively. The two crystalline 2-D frameworks Pd@Cu-MOF and Cu-MOF were characterized as microporous materials with Brunauer–Emmett–Teller (BET) surface areas of 12 m2 g−1 and 33 m2 g−1, respectively. Gas adsorption experiments revealed a low uptake of carbon dioxide by these materials attributed to crystal-to-crystal transformation of the MOFs upon activation. [ABSTRACT FROM AUTHOR]

Four new Zn(II) metal–organic frameworks (MOFs): {[Zn(L1)(BTEC)0.5]·3.1H2O}n (1), {[Zn(L2)0.5(BTEC)0.5]·1.5H2O}n (2), {[Zn2(L3)(BTEC)(H2O)]·H2O}n (3), and {[Zn2(L4)(BTEC)]·H2O}n (4) were constructed by selecting N-containing linkers with the Zn(II)/H4BTEC system (H4BTEC = 1,2,4,5-benzenetetracarboxylic acid, L1 = 1,4-bis(1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)cyclohexane, L2 = 1,4-bis(1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)butane, L3 = 1,5-bis(1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)pentane, L4 = 1,4-bis(1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)methyl)benzene). Structural analyses indicate that 1 exhibits a (3,4)-connected 2D 3,4L13 sheet. 2 manifests a rare (4,4,4)-connected 2D 4,4,4L10 layer. 3 displays an unprecedented (3,3,4,4,4)-connected 3D network based on the point symbol {4·82}2{42·6·83}2{42·6}2{42·82·102}{84·122} and 4 presents an unusual 4,4,4,6,6T3 3D network with a 5-node (4,4,4,6,6)-connected network. The structural variety of these Zn(II) MOFs demonstrates that different N-containing ligands can induce the BTEC4− linkers exhibiting various coordination modes, exerting a great influence on the final MOF frameworks. Further, MOFs 1–4 are favorable dual-functional fluorescent sensors for the detection of Fe3+/acetylacetone with high sensitivity and selectivity. To our knowledge, this is the first report of fluorescent MOFs based on L1–L4 ligands for the detection of Fe3+ and acac in the naked eye range. [ABSTRACT FROM AUTHOR]

Two highly stable metal–organic frameworks (MOFs) assembled by a flexible 1,4-bis(2-methylimidazol-1-yl)butane (bib), and two different aromatic carboxylate coligands, namely, [Zn(BDC–OH2)(bib)] (1) and [Cd3(BTC)2(bib)(DMF)3] (2) (H2BDC–OH2 = 2,5-dihydroxyterephthalic acid, H3BTC = 1,3,5-benzenetribenzoic acid), were designed and synthesized. 1 showed a 4-fold interpenetration of 4-connected dia-type topological net. In 2, the 3D topological structure can be viewed as a (3,4,5)-connected network, and its Schläli point is {4·62}2 {42·6·83} {46·89}. Different auxiliary carboxylate ligands were examined with respect to the building of various structures. 1 and 2 have outstanding photocatalytic behaviors for the disintegration of methyl violet (MV) under UV irradiation. [ABSTRACT FROM AUTHOR]

Three isostructural lanthanide metal–organic frameworks (Ln-MOFs), {[Ln(L)(H2O)2]·H2O}n (M-Ln, Ln = Eu/Tb/Dy), were prepared with a flexible 3,5-(4-carboxybenzyloxy) benzoic acid (H3L) ligand and lanthanide ions by a solvothermal method. M-Ln are two-dimensional (2D) grid layer-stacking frameworks. M-Eu exhibits excellent chemical stabilities against organic solvents and shows strong luminescence. The experimental results indicated that M-Eu could be used as an ideal fluorescent probe to detect nitrobenzene (NB) in different solvents with a lower detection limit. M-Eu can also be used as a pH sensor because of its superior water stability. Furthermore, M-Eu and M-Tb show unique strong luminescence properties with high absolute quantum yields. The quantum yields can even reach up to 11.8% and 60.5%, respectively. Simultaneously, various kinds of heterometallic doped M-Eu x Tb 1−x MOFs were acquired by tuning the ratios of Eu3+/Tb3+ ions, showing the unique color changes from red, orange-red, orange, orange-yellow, light yellow, yellow to green. [ABSTRACT FROM AUTHOR]

Two series of lanthanide-based metal–organic frameworks, namely {[Ln(BIPA-TC)0.5(DMA)2(NO3)]·DMA·H2O}n (1-Ln, Ln = Eu, Dy, Sm, Nd) and {[Ln2(BIPA-TC)1.5(DMA)3(H2O)2]·2DMA·2H2O}n (2-Ln, Ln = Eu, Dy, Sm, Nd), were successfully constructed via a solvent regulation strategy based on a π-electron rich tetra-carboxylate ligand (H4BIPA-TC). 1-Ln shows a 4-connected lvt topology with the point symbol of {42·84}, but 2-Ln displays a new 4,4,6-connected wxk1 topology with the point symbol of {43·83}4{46·66·83}2{86}. The solid-state luminescence property and the microporous nature of Eu-MOFs (1-Eu and 2-Eu) indicate that they can potentially be used as luminescent sensors. Fluorescence measurements indicate that Fe3+ exhibits the quenching effect for 1-Eu with the quenching efficiency of 93.1%. 2-Eu is the first MOF sensor for Mg2+ with the lowest detection limit of 1.53 × 10−10 mol L−1 and displays good recyclable capability. Simultaneously, in the presence of other metal ions (Ca2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pd2+, Al3+, Cr3+and Fe3+), 2-Eu can maintain the selective sensing of Mg2+, indicating its potential for Mg2+ turn-on sensing. [ABSTRACT FROM AUTHOR]

A series of multifunctional metal–organic frameworks (MOFs), SNU-170–SNU-176, has been synthesized using ligands, in which various functional pendants such as –NH2, –SMe, –OMe, –OEt, –OPr, and –OBu are attached to the phenyl ring of 4-(2-carboxyvinyl)benzoic acid. The MOFs are isostructural but the interpenetration depends on the pendant group of the ligand. The MOFs exhibit high adsorption capacities for H2, CO2, and CH4 gases, ligand-based photoluminescence, and chemical sensing abilities, all being affected by the pendant group. All of the as-synthesized MOFs can sense nitroaromatics by luminescence quenching, and some of the activated MOFs can sense the type of solvents by the altered emission maxima with enhanced intensity. In particular, SNU-176 synthesized from a mixture of two different ligands with –SMe and –OMe pendants shows higher gas adsorption capacities than the MOFs synthesized from the individual ligands (SNU-171 and SNU-172). It also shows the ability to differentiate nitrobenzene (NB) and 2,4-dinitrotoluene (DNT) unlike the MOFs composed of single ligands. [ABSTRACT FROM AUTHOR]

The electrode design is of considerable importance for developing enhanced electrochemical sensing platforms. Conductive metal–organic frameworks (MOFs), with high surface area, high conductivity, and large pore volume, possess an ideal architecture for the detection of molecules. In this study, we report the first electro-oxidation of glucose in an alkaline solution using conductive Ni-based metal–organic framework nanosheet arrays on carbon cloth (Ni-MOF NSAs/CC) as a non-noble metal catalyst. Compared with a number of ligands coordinated to nickel salt, 2,3,6,7,10,11-hexaaminotriphenylene hexahydrochloride was selected as the best ligand to synthesize Ni-MOF because it has the highest electrocatalytic activity for glucose oxidation. The 3D Ni-MOF NSAs/CC electrode, as multifunctional sensors, was used to detect glucose with a low detection limit of 0.57 μM (S/N = 3), a wide linear range of 0.001–7 mM, high sensitivity of 13428.89 μA mM−1 cm−2, and good selectivity. The results demonstrate that the as-prepared Ni-MOF NSAs/CC has considerable development and application potential for clinical medical testing. [ABSTRACT FROM AUTHOR]

In a one-pot self-assembly reaction of Co(OAc)2·4H2O, thiophene-2,5-dicarboxylic acid (H2tdc) and four different bis(tridentate) polypyridyl spanning ligands under ambient conditions, a series of structurally diverse metal–organic frameworks has been synthesised and characterized by single crystal X-ray diffraction: {[Co2(tdc)2(tpbn)(H2O)2]·solvent}n (solvent = 2H2O, 1; solvent = 2CH3OH, 2H2O, 1a), {[Co2(tdc)2(tphn)]·solvent}n (solvent = H2O, 2; solvent = CH3OH, 2.5H2O, 2a), {[Co2(tdc)2(tpchn)(H2O)2]·solvent}n (solvent = 5H2O, 3; solvent = C2H5OH, 2H2O, 3a), and {[Co2(tdc)2(tpxn)]·solvent}n (solvent = 6H2O, 4; when no solvent, 4a), where tpbn (N,N′,N′′,N′′′-tetrakis(2-pyridylmethyl)-1,4-diaminobutane), tphn = N,N′,N′′,N′′′-tetrakis(2-pyridylmethyl)-1,6-diaminohexane, tpchn = N,N′-(cyclohexane-1,4-diylbis(methylene))bis(1-(pyridin-2-yl)-N-(pyridin-2-ylmethyl)methanamine) and tpxn = N,N′-(1,4-phenylenebis(methylene))bis(1-(pyridin-2-yl)-N-(pyridin-2-ylmethyl)methanamine). There is a profound effect of the nature of spacer between the alkyl nitrogens in the spanning ligands (flexible vs. semiflexible) on the molecular structures of 1a–4a. The notable differences are (a) the binding mode of the tridentate part of polypyridyl ligands to the Co(II) center is facial in 1a, 3a and 4a but meridional in 2a, (b) the Co(II) centers in 1a–3a are hexacoordinated (with a coordinated water in 1a and 3a) but are pentacoordinated in 4a, and (c) the binding mode of tdc linker is bis(monodentate) in 1a, 3a and 4a but chelated in one end and monodentate in the other end in 2a. Thus, the overall framework structure of 1a, 2a, 3a and 4a is cis-decalin type 2D polymer, ladder-shaped 1D polymer, hexagonal 2D net and cis-decalin type 2D polymer, respectively. Their thermal stabilities have been established by thermogravimetric analysis (TGA). The presence of an unsaturated metal center in 4 has provided us an opportunity for its use as an efficient Lewis acid catalyst for the Knoevenagel condensation reaction of malononitrile with various aldehydes (100% conversion in 60 minutes with 2 mol% catalyst in methanol). [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]

Tailoring the structures and properties of metal–organic frameworks (MOFs) is very important for developing porous MOFs for targeted applications. Bent diisophthalate ligands offer a rich opportunity to construct MOFs with variable topologies because of their conformation flexibility and diversity. In this work, by employing a substituent-induced ligand conformation regulation strategy, we designed and synthesized three bent diisophthalate ligands bearing different substituents, and successfully constructed their corresponding dicopper paddlewheel-based MOFs under suitable solvothermal conditions. As revealed by single-crystal structural analyses, they feature distinct topological structures, depending on the attached substituents. Interestingly, the methoxy-functionalized MOF exhibits a novel topology, thus enriching the structural diversity of copper-bent diisophthalate frameworks. Furthermore, their gas adsorption properties with respect to C2H2, CO2, and CH4 were systematically investigated, revealing their promising potential for industrially important C2H2/CH4 and CO2/CH4 separations. More significantly, their separation performance can be greatly tailored by changing the substituents. Under ambient conditions, C2H2 and CO2 uptake capacities vary from 157.7 to 184.5 cm3 (STP) g−1, and 90.8 to 101.3 cm3 (STP) g−1, respectively, while C2H2/CH4 (50/50, v/v) and CO2/CH4 (50/50, v/v) adsorption selectivities range from 30.0 to 36.2, and 5.27 to 6.01, respectively. The amino-functionalized MOF performed better than the other two counterparts, which might be due to the synergistic effect arising from Lewis basic amino groups, higher density of open copper sites, and more suitable pore size. This work not only reported three MOFs for preferable adsorption of C2H2 and CO2 over CH4, but also demonstrated that the substituent-driven ligand conformation regulation is a facile way to modulate the structures and thus gas adsorption properties of MOFs. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) can be utilized as antibacterial agents due to their effective antibacterial activities. Four three-dimensional (3D) Cu-MOFs formulated as [Cu2(Glu)2(μ-L)]·x(H2O) (Glu is glutarate, and L is bpy = 4,4′-bipyridine (1), bpa = 1,2-bis(4-pyridyl)ethane (2), bpe = 1,2-bis(4-pyridyl)ethylene (3), and bpp = 1,2-bis(4-pyridyl)propane (4)) were synthesized by hydrothermal reactions or modified literature methods. Their solid-state structures were slightly modified to increase their hydrolytic stabilities in aqueous solution. Despite the seemingly sufficient void spaces in all the solvent-free MOFs, only the thermally activated form of MOF 2 displayed selective gas uptake ability for CO2 over N2 and H2. The antibacterial activities of the four Cu-MOFs, 1, 2, 3, and 4, were investigated by determining their minimal bactericidal concentration (MBC) values against five strains of bacteria, including E. coli, S. aureus, K. pneumonia, P. aeruginosa, and MRSA, which can be easily met in our daily surrounding environments. Although these Cu-MOFs were found to be structurally very stable in aqueous medium during antibacterial activity tests, they exhibited excellent antibacterial activities against all five kinds of bacteria, including Gram-positive bacteria (S. aureus and MRSA) and Gram-negative bacteria (E. coli, K. pneumonia, and P. aeruginosa), with very low MBCs. The robust 3D frameworks with surface active metal sites rather than the small amount of leached CuII ions may participate more strongly in inactivating various kinds of bacteria and reduce potential cytotoxicity mainly caused by leached metal ions. [ABSTRACT FROM AUTHOR]

Six metal–organic frameworks with the combination of a novel tripodal ligand tris[4-(1H-imidazol-1-yl)phenyl]phosphine oxide (tipo) and different polycarboxylates, namely [Zn2(bpdc)2(tipo)(H2O)]·5H2O (1), [Cd(tipo)2][Cd2(bdc)3]·4H2O (2), [Cd2(ndc)2(tipo)2]·3H2O (3), [Cd2(bpedc)2(tipo)2]·15H2O (4), [Cd2(hfdc)2(tipo)2]·10H2O (5) and [Ni2(tipo)2(bpedc)(H2O)4]·2NO3·2DMF (6), were synthesized and structurally characterized. Compound 1 featured a 2D → 3D parallel polycatenation of a 3,3,4-connected net with an unusual 4 degrees of catenation and an index of separation of 2. Compound 2 showed an unprecedented polycatenation of charged networks 2D kgd and 3D pcu constructed by different organic ligands. Compound 3 exhibited a combination of a 2D → 3D parallel polycatenation of the sql net and polythreading. Compound 4 featured a 4-fold interpenetration of a 3,5-connected 3,5T1 net. Compound 5 displayed an unusual 2-fold interpenetration of the sdd net. Compound 6 presented a 2-fold interpenetration of the 3,4-connected bey net with a cationic framework. The luminescence properties of 1–5 in the solid state were investigated. Also, compound 6 showed a tendency for rapid selective dye capture and highly efficient Cr2O72− removal from aqueous solution. [ABSTRACT FROM AUTHOR]

Two metal–organic frameworks (MOFs) made of indium and 1,3,5-tris(4-carboxyphenyl)benzene (H3btb) and having a layered structure have been synthesized under solvothermal conditions: [In(btb)(H2O)(DMF)]·L (InPF-50) and [In2(btb)2Cl2]2−·[(CH3)2NH2]22+·L (InPF-51). The structures of both materials have been determined by single crystal X-ray diffraction. The synthetic study which has been carried out demonstrates the influence of the selected indium salt in obtaining each MOF. The structure of both materials consists of pairs of catenated layers, where the metal atoms display coordinated solvent ligands that provide potential open metal sites. The accessibility to these sites along with the presence of Lewis basic sites in the form of uncoordinated oxygen atoms make InPF-50 and -51 efficient catalysts for the four-component Ugi reaction. We attribute this high activity not only to the presence of both acid and basic sites, but also to their convenient locations in the MOF structures. This is further supported by the comparison with [In3O(btb)2(HCO2)]·L, InPF-110, a highly porous indium MOF that only displays Lewis acid sites, and shows lower activity. [ABSTRACT FROM AUTHOR]

Four new Zn(ii)/Cd(ii)-based metal–organic frameworks (MOFs), namely {[Cd(tmdb)(bib)0.5]·solvents}n (YZ-7, YZ stands for the initials of the author Yong-Zheng Zhang), {[Cd(tmdb)(bmib)0.5]·solvents}n (YZ-8), {[Zn2(tmdb)2(bmib)]·solvents}n (YZ-9) and {[Zn2(tmdb)2(bmip)2]·solvents}n (YZ-10) have been solvothermally synthesized by using a semi-rigid ligand, 4,4′-(H-1,2,4-triazol-1-yl)methylene-dibenzoic acid (H2tmdb), and a series of secondary bis-imidazole ligands (bib = 1,4-bis(1H-imidazol-1-yl)benzene, bmib = 1,4-bis(2-methyl-1H-imidazol-1-yl)benzene, and bmip = 1,3-bis(2-methyl-1H-imidazol-1-yl)propane). By tuning the flexibility of the auxiliary ligands, these MOFs could be modulated from unstable (YZ-7–YZ-9) to stable (YZ-10) frameworks. Therefore, the gas adsorption properties of YZ-10 are further studied. Interestingly, it shows excellent CO2 selective uptake over CH4 and N2. At 298 K, both selectivities of CO2/CH4 and CO2/N2 show increasing trends and significantly reach 133.2 and 19.9 at 1 atm, respectively. Also, YZ-10 shows uncommon H2 selective uptake over N2 at 77 K. Moreover, the luminescence properties of YZ-8–YZ-10 were studied in the solid state at room temperature. [ABSTRACT FROM AUTHOR]

Five novel Ln-MOFs associated with the mixed ligands of 4-(pyridin-3-yloxy)-phthalic acid (H2ppda) and terephthalic acid (H2bdc), namely, [Ln(ppda)(bdc)0.5(C2H5OH)(H2O)]n (Ln = Sm (1), Eu (2), Gd (3), Tb (4), and Dy (5)) were synthesized under the solvothermal conditions. Compounds 1–5 exhibit the isostructural 2D layered structures. The solid-state luminescence properties of compounds 1, 2, 4 and 5 were investigated in detail. It was found that compound 4 not only detected nitrobenzene derivatives-based explosives with high selectivity, sensitivity, and recyclability, but also served as an excellent selective sensing material for Fe3+ ion and Cr2O72− ion. In particular, it is worth noting that the detection limit of TNP can reach 3.0 × 10−8 M. It was found that the free oxygen atoms of the ether bond, which function as the Lewis basic sites in Ln-MOFs, might interact with metal ions. In addition, the sensing mechanisms of 4 for different analytes were explored further. [ABSTRACT FROM AUTHOR]

The combination of an angular diisophthalate ligand, 5,5′-(naphthyl-2,7-yl)diisophthalate (H4L), and copper ions under different solvothermal conditions afforded two polymorphous metal–organic frameworks (ZJNU-77 and ZJNU-78) with the same framework composition of [Cu2(L)(H2O)2], providing a platform to investigate the relationship between MOF polymorphism and gas adsorption properties. As determined by single-crystal X-ray diffraction, ZJNU-77 and ZJNU-78 exhibited three-dimensional networks crystallizing in different space groups. Their structural differences were mainly manifested by the ligand's conformation, the level of framework interpenetration and the network's topology. Interestingly, gas adsorption studies showed that the two compounds after desolvation displayed comparable gas adsorption properties with respect to C2H2, CO2 and CH4, despite their different surface areas and pore volumes. The C2H2, CO2, and CH4 uptake capacities at 298 K and 1 atm are 120.2, 78.1, and 18.4 cm3 (STP) g−1 for ZJNU-77, and 122.0, 82.0, and 18.9 cm3 (STP) g−1 for ZJNU-78, respectively. The IAST adsorption selectivities for the equimolar C2H2/CH4 and CO2/CH4 mixtures are 28.6 and 5.7 for ZJNU-77, and 28.4 and 5.9 for ZJNU-78 at 298 K and 1 atm. These results indicate that besides the surface area, the pore size also plays a crucial role in gas adsorption. This work not only represents an intriguing example of MOF polymorphism achieved by controlling solvothermal conditions, but also provides an insight into the correlation between MOF polymorphism and gas adsorption properties. [ABSTRACT FROM AUTHOR]

A new, azide-functionalized Al(iii)-based metal–organic framework (MOF) denoted as CAU-10-N3 (1, CAU = Christian-Albrechts-University) and consisting of the 5-azido-isophthalic acid (H2IPA-N3) ligand was employed as a reaction-based fluorescent turn-on probe for the detection of H2S. The activated compound (1′) showed fast, selective and highly sensitive sensing properties for extracellular H2S in HEPES buffer (10 mM, pH = 7.4). The material retained its high selectivity even in the presence of possibly competing biological species. The limit of detection of 1′ for H2S is 2.65 μM, which is lower than the earlier reports on MOFs for H2S sensing. The material displayed a short response time (420 s) and a significant increase (20-fold and 26-fold after 1 and 7 min of addition of Na2S, respectively) in the fluorescence intensity towards H2S. Macrophage cells loaded with probe 1′ exhibited blue fluorescence with a response time of 15 min after Na2S addition, indicating the suitability of the probe for intracellular H2S detection. Moreover, CAU-10-N3 featured excellent detection performance (quick response and 32-fold increment in fluorescence intensity after 7 min of Na2S addition) in water. Hence, it can be utilized to regulate the H2S level in aqueous samples collected from the environment. [ABSTRACT FROM AUTHOR]

Combining Zn(NO3)2·6H2O with a series of dicarboxylic acids in the presence of the N,N′-ditopic ligand di(4-pyridyl)-1H-pyrazole (Hdpp) results in a series of mixed-linker metal–organic frameworks (MOFs) that have been crystallographically characterised. The reaction with 1,4-benzenedicarboxylic acid (H2bdc) gives [Zn2(bdc)2(Hdpp)2]·2DMF 1, which shows Zn2(μ-carboxylate)2(carboxylate)2 secondary building units (SBUs) linked by bdc ligands into sheets, and these are pillared by the Hdpp linkers into a doubly-interpenetrated three-dimensional network. The reaction with 1,4-naphthalene dicarboxylic acid (H2ndc-1,4) gives two products: [Zn2(1,4-ndc)2(Hdpp)]·4DMF 2a forms a three-dimensional network in which sheets, formed from Zn2(carboxylate)4‘paddle-wheel’ SBUs being linked by 1,4-ndc, are connected together by Hdpp pillars, whereas [Zn(1,4-ndc)(Hdpp)]·DMF 2b forms a fourfold interpenetrated structure based on diamondoid networks with single zinc centres as nodes. The reaction with 1,3-benzenedicarboxylic acid (H2mbdc) produces [Zn(mbdc)(Hdpp)]·DMF 3, which forms a two-dimensional network with (4,4) topology in which ZnO2N2 nodes are interlinked by mbdc and Hdpp linkers. The reaction with 5-methyl-1,3-benzenedicarboxylic acid (H2mbdc-Me) also forms a two-dimensional network structure, [Zn2(mbdc-Me)2(Hdpp)2]·DMF 4, albeit wherein dicarboxylates bridge between zinc-dicarboxylate tapes, themselves formed by interlinking of Zn2(μ-carboxylate)2(carboxylate)2 SBUs similar to those in 1. Finally, the reaction with 2,6-naphthalene dicarboxylic acid (H2ndc-2,6) yields two crystalline species, both having the formula [Zn2(2,6-ndc)2(Hdpp)]·DMF 5a/5b and possessing infinite zinc-carboxylate chain motifs interlinked by both naphthalene rings and Hdpp linkers into a three-dimensional framework. In compounds 1, 2b, 3 and 4, the pyrazole NH groups are involved in hydrogen bonding that serves to link either interpenetrated networks or neighbouring sheets together. However, in 2a and 5a/5b the NH groups project into the pores of the framework enabling interactions with guest molecules. [ABSTRACT FROM AUTHOR]

When Ni(NO3)2·6H2O and N,N′-di(4-pyridyl)-1,4,5,8-naphthalenetetracarboxydiimide (DPNDI) are reacted, a one-dimensional coordination polymer (1) is formed. However, analogous reactions with either terephthalic acid (2) or 2,6-naphthalenedicarboxylic acid (3) and DPNDI affords two-dimensional, pillared metal–organic frameworks. 2 and 3 contain rectangular voids of different dimensions which are dictated by the carboxylate ligand and the arrangement of the {[M(k2-O2NO)]2(μ2-O2CR)2} secondary building unit (SBU) that forms the nodes of the framework. The role of SBU geometry, intermolecular face-to-face π–π and lone pair–π interactions involving the DPNDI ligands are discussed. [ABSTRACT FROM AUTHOR]

Mixed 2-(1-hydroxy-ethyl)-3H-benzoimidazole-5-carboxylic acid and tetrazole ligands were used to synthesize three new zeolite-like metal–organic frameworks with diverse structures, and the resulting compound 2 shows high chemical stability and high CO2 uptake capacity. [ABSTRACT FROM AUTHOR]

The construction of coordination polymers based on flexible ligands in a pre-designed manner is a difficult task which needs deep knowledge of the ligands involved. With this objective in mind, we have investigated the complex formation between methanetriacetic acid (H3mta) and copper(ii) in the presence of 2,2′-bipyridine (bpy) as a blocking coligand to limit the number of coordination sites available at the metal ion. In this primary target, five complexes of formulae [Cu3(bpy)6(mta)](ClO4)3·2H2O (1), [Cu4(bpy)6(mta)2(H2O)2](ClO4)2·20H2O (2), [Cu(bpy)(Hmta)]n (3), {[Cu4(bpy)4(mta)2](ClO4)2·3H2O}n (4) and {[Cu3(mta)2(bpy)3(H2O)]3·3dmf·13H2O}n (5) were synthesized and their crystal structures were solved by single crystal X-ray diffraction. Compounds 1 and 2 are tri- and tetranuclear species, respectively, whereas 3 and 4 are one-dimensional compounds and 5 is a three-dimensional coordination polymer. This series of complexes reveals that methanetriacetate behaves as a tritopic ligand which keeps its C3 symmetry despite its flexibility. On the basis of the structural knowledge of 1–5, a (6,3)-honeycomb network of formula {[Cu12(tppz)6(mta)4(H2O)24](NO3)12·66H2O}n (6) [tppz = tetrakis(2-pyridyl)pyrazine] was prepared by design where each methanetriacetate ligand acts as a three-connected node. Magnetic susceptibility measurements in the temperature range 2.0–300 K for 1–6 show the occurrence of very weak antiferro- (1 and 2) and ferromagnetic (3–5) interactions, whereas an intermediate antiferromagnetic coupling (J = −43 cm−1, the spin Hamiltonian being defined as H = −JS1·S2) is observed for 6. The different size and nature of the magnetic interactions in 1–6 are analyzed and discussed in the light of the respective exchange pathways involved. [ABSTRACT FROM AUTHOR]

A series of highly thermally stable lanthanide metal–organic frameworks formulated as [Ln2(TATB)2(DMSO)6]·DMF·DMSO·H2O [Ln = La (1), Ce (2), Pr (3), Sm (4), Eu (5)] and [Ln2(TATB)2(DMSO)5(CH3OH)]·DMF·DMSO·2H2O [Ln = Nd (6), Gd (7), Tb (8)] (TATB3− = 4,4′,4′′-s-triazine-2,4,6-triyl-tribenzoate, DMF = N,N-dimethylformamide and DMSO = dimethylsulfoxide) have been successfully synthesized under solvothermal conditions and characterized by single crystal X-ray diffraction, infrared (IR) spectroscopy, elemental analysis, thermogravimetric analyses (TGA) and powder X-ray diffraction (PXRD). Single crystal X-ray diffraction analysis reveals that all of the compounds are isomorphous, crystallize in the triclinic space group P̅1 and exhibit two-dimensional (2D) (3,3)-connected layered structures with the Schläfli symbol {63}. Solid-state photoluminescence measurement illustrates that compounds 5 and 8 exhibit remarkable red and green luminescence emissions with lifetimes at the millisecond scale, respectively, while complexes 3, 4, and 6 display characteristic luminescence emissions in the near-infrared region. With careful adjustment of the relative concentration of the doping Eu3+ and Tb3+ ions in the La3+ complex, the color of the luminescence can be modulated, and white-light emitting materials can be successfully obtained. [ABSTRACT FROM AUTHOR]

Four three-dimensional (3D) luminescent metal–organic frameworks (MOFs), Zn2(HL1)(H2O)0.8 (1), Cd2(L1)(DMF)2 (2), [Zn3(HL2)2]·[(CH3)2NH2]4 (3), and [Cd3(L2)2]·[(CH3)2NH2]6 (4) (H5L1 = 3,5-di(3′5′-dicarboxyphenyl)benzoic acid, H6L2 = 3,4-di(3,5-dicarboxyphenyl)phthalic acid, DMF = N,N-dimethylformamide), have been successfully assembled based on rigid carboxylate ligands. The four compounds have been characterized by elemental analysis, infrared (IR) spectroscopy, thermogravimetric analysis (TGA), single-crystal X-ray diffraction, powder X-ray diffraction (PXRD) and fluorescence spectroscopy. Compound 1 is a (5,5)-connected 3D framework with a {45·65} topology. Compound 2 possesses a (5,5)-connected 3D framework with a {47·63} topology. Compounds 3 and 4 display a (4,4,6)-connected 3D framework with a {42·64}2{44·611}2{44·62} topology. Remarkably, the four presented compounds show luminescence changes in the presence of metal ions. Interestingly, all of them exhibit highly selective sensing of Fe3+ ions and the luminescence is quenched in a 1.1 × 10−3 M DMF solution of Fe3+ ions. Moreover, the four compounds possess reasonable recyclability and reproducibility of luminescence after regeneration. The exceptional sensitivity and reusability of the four compounds make them excellent Fe3+ sensors in the future. [ABSTRACT FROM AUTHOR]

Four new metal–organic frameworks (MOFs), [Co3(TCPB)2(CH3OH)4]·4DMF (1), [Cd3(TCPB)2(H2O)4]·3DMF·19H2O (2), [Mn3(TCPB)2(H2O)2(DMF)2]·2DMF (3), and [Zn2(μ3-OH) (TCPB)(H2O)(DEF)]·3DEF (4) (H3TCPB = 1,3,5-tri(4-carboxyphenoxy)benzene), have been successfully synthesized and structurally characterized. Structural analyses show that complexes 1–3 present two-dimensional (3,6)-connected kgd net topology with the Schläfli symbol of (43)2(46·66·83) based on linear trinuclear M3(COO)6 (M = Co, Cd, and Mn) secondary building units (SBUs) and display distinct one-dimensional (1-D) channels. Complex 4 (Zn-TCPB) exhibits a rare three-dimensional twofold interpenetrated (3,6)-connected rutile topology with the Schläfli symbol of (42·610·83) (4·62)2 based on the tetranuclear Zn4(μ3-OH)2(COO)6 clusters, which shows three different types of 1-D opening channels. In addition, as an anode material, the complex 4 (Zn-TCPB) electrode exhibits an irreversible high capacity in the first discharge process and a reversible lithium storage capacity of up to about 455 mA h g−1 at 0.1 A g−1 after 100 cycles. This might provide a new method for finding a promising candidate for the electrode materials in lithium-ion batteries. [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]

Reports of the design and synthesis of adjustable proton-conducting metal–organic coordination hybrids are still rare. Herein, we synthesized and characterized two coordination compounds: Cu(HL)L (1) and H4Mo8O24L4·3H2O (2) (L = 4-(1H-imidazolyl) benzoic acid). In addition, we first report the adjustment of the proton conductivity of metal–organic hybrids via varying the coordination mode of a specific ligand L (L = 4-(1H-imidazolyl) benzoic acid). Compound 1 has a proton conduction of 1.08 × 10−3 S cm−1 at 97% RH at room temperature, whereas under the same conditions, 2 has an obviously lower proton conduction of 1.09 × 10−6 S cm−1. The proton conduction of the two hybrids varied by nearly one thousand fold. [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]

A novel porous coordination polymer based on a Co-nitroimidazolate–dicarboxylate pillared-layer network, namely, [Co7(bdc)6(nIm)2(H2O)6]·3H2O·3DMF, (1, H2bdc = 1,4-benzenedicarboxylic acid, nIm = 2-nitroimidazole), has been synthesized by a solvothermal reaction. The microporous layers of 1 consisted of two kinds of SBUs, six-connected Co3(O2CR)6 and three-connected [Co2(O2CR)3]+, forming unprecedented Co3-Co2-bdc-based layers with three types of diamonded grids in the bc plane. The layers are further linked by bidentate-bridging nIm ligands as pillars into a 3-D metal–organic framework with two kinds of rectangular channels parallel to the c axis. It is worth mentioning that compound 1 also exhibits uniquely polyhedral cages with a maximum diagonal dimension of up to 31.019 Å, which has fallen in the scope of mesoporous (2–50 nm). To systematically evaluate the channels and special cages, the adsorption ability of 1 was measured by N2, H2 and CO2 sorption experiments. Topological analysis indicates that compound 1 adopts a new topological structure with a point symbol of {412·614·82}{46}2. Moreover, thermal gravimetric analysis (TGA) of as-synthesized 1 reveals a stability range up to 311 °C. [ABSTRACT FROM AUTHOR]

The precise tuning of the structural and chemical features of microporous metal–organic frameworks (MOFs) is a crucial endeavour for developing materials with properties that are suitable for specific applications. In recent times, techniques for preparing frameworks consisting of mixed-metal or ligand compositions have emerged. However, controlled spatial organisation of the components within these structures at the molecular scale is a difficult challenge, particularly when species possessing similar geometries or chemical properties are used. Here, we describe the synthesis of mixed-metal and ligand variants possessing the Mn3L3 (Mn-MOF-1; H2L = bis(4-(4′-carboxyphenyl)-3,5-dimethylpyrazolyl)methane) structure type. In the case of mixed-ligand synthesis using a mixture of L and its trifluoromethyl-functionalised derivative (H2L′ = bis(4-(4′-carboxyphenyl)-3,5-di(trifluoromethyl)pyrazolyl)methane), a mixed-ligand product in which the L′ species predominanantly occupies the pillar sites lining the pores is obtained. Meanwhile, post-synthetic metal exchange of the parent Mn3L3 compound using Fe2+ or Fe3+ ions results in a degree of cation exchange at the trinuclear carboxylate-based clusters and metalation at the pillar bispyrazolate sites. The results demonstrate the versatility of the Mn3L3 structure type toward both metal and ligand substitutions, and the potential utility of site-specific functionalisations in achieving even greater precision in the tuning of MOFs. [ABSTRACT FROM AUTHOR]

Three octamolybdate-based metal–organic complexes constructed from a pyridyl-carboxylate ligand containing an amide group, 3-(2-pyridinecarboxylic acid)amido pyridine (HPCAP), namely, H2{[Cu3(PCAP)4(H2O)2](β-Mo8O26)}·10H2O (1), H{[Cu(PCAP)(H2O)](β-Mo8O26)0.5} (2) and H2[Co(H2O)6][Co2(PCAP)4(γ-Mo8O26)(H2O)2]·10H2O (3), have been successfully synthesized under hydrothermal or solvothermal (methanol–water mixed solvent) conditions. Single-crystal X-ray analyses reveal that compound 1 is a 2D layer based on infinite 1D [Cu3(PCAP)4]n2n+ chains and bidentate β-Mo8O264− anions. In compound 2, 1D “thin centipede” [Cu2(PCAP)2]n2n+ chains were connected by tetradentate β-Mo8O264− anions through the Cu–O bond to form a 2D network. In compound 3, γ-Mo8O264− anions were connected by adjacent [Co2(PCAP)4(H2O)2] moieties through Co–O and Mo–N bonds forming an uncommon 1D “fat centipede” chain. The adjacent chains were further extended to a 2D supramolecular network through hydrogen bonding interactions. The title compounds represent the first examples of introducing a pyridyl-carboxylate ligand containing an amide group into the POM system. The pH value, solvent and metal ions play key roles in the construction of the final architectures and show a great influence on the structural diversities of the title compounds. The electrochemical properties of compound 1 and the photocatalysis properties of the title compounds have been reported. [ABSTRACT FROM AUTHOR]

This manuscript addresses the synthesis, structural characterization and optical properties of a 1D coordination polymer (CPs) and 2D and 3D Metal–Organic Frameworks (MOFs) obtained from lanthanide metals, 3-hydroxinaftalene-2,7-disulfonic acid (3-OHNDS) and two different phenanthroline derivates as ancillary ligands. The first is a family of 2D compounds with formula [Ln(3-OHNDS)(H2O)2], where Ln = La(1), Pr(2), Nd(3) and Sm(4). The addition of 1,10-phenanthroline (phen) in the reaction produces 1D compounds with general formula [Ln(3-OHNDS)(phen)(H2O)]·3H2O, where Ln = La(5), Pr(6), Nd(7) and Sm(8). Finally, the synthesis with 3,4,7,8-tetramethyl-1,10-phenanthroline (3,4,7,8-TMPhen) as an ancillary ligand results in the formation of the 3D [La(3-OHNDS)(3,4,7,8-TMphen)(H2O)] (9) compound. The photoluminescence (PL) properties of 1D and 2D compounds were fully investigated in comparison with the 3-OHNDS ligand. One of the most important results was the obtaining of a white-light single-emitter without adding dopant atoms in the structure. With all these results in mind it was possible to establish structure–property relationships. [ABSTRACT FROM AUTHOR]