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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]

In this paper, PS (polystyrene)/Au/ZIF-8 (zeolite imidazole framework-8) hybrid structures were synthesized for the first time as novel SERS active substrates. A series of substrates were successfully prepared by changing the Au sputtering time (5 min, 8 min, 10 min, 15 min and 20 min). When the sputtering time of Au was 10 min, the 4-mercaptobenzoic acid (4-MBA) molecules on the PS/Au/ZIF-8 substrate exhibited the maximum SERS enhancement. Meanwhile, the hybrid SERS substrate exhibited good SERS reproducibility, and we successfully obtained an ultrahigh enhancement factor of 1.67 × 106. Probe molecules can be easily enriched on the surface of the PS/Au/ZIF-8 composite due to their large pore volume and the high surface area of metal organic framework (MOF) materials. ZIF-8 also guides the probe molecules to the "hot-spots" to enhance the SERS signals. Moreover, the detection limit of R6G molecules achieved was 10−12 M when PS/Au(10 min)/ZIF-8 was used as a highly sensitive SERS sensor. This strategy has brought new insights to SERS research, and has also provided a new idea for the application and development of SERS in MOF-based SERS materials and ultra-sensitive analyses. [ABSTRACT FROM AUTHOR]

Considering the coordination advantage of N-heterocyclic carboxylate ligands in the construction of metal–organic frameworks (MOFs), we hope to adopt them to build up more structurally stable MOFs for proton conduction research. Therefore, the multifunctional ligand of 2-(2-carboxyphenyl)-4,5-imidazole dicarboxylic acid (o-CPH4IDC) was selected by us. Consequently, two highly water-stable Ba(II) and Cd(II) MOFs, {[Cd(o-CPH2IDC)(4,4′-bipy)0.5(H2O)2]·3H2O}n (1) (4,4′-bipy = 4,4′-bipyridine) and [Ba(o-CPH2IDC)]n (2) were made. The further study of water-assisted proton conduction for 1 and 2 demonstrated that both were temperature- and humidity-dependent proton conductors, and their best proton conductivities could reach 10−4 S·cm−1 at 100 °C and 98% RH. The vehicle mechanism can be proposed for 1 and 2 by calculating the activation energy and by analysing their crystal structures. Apparently, the adsorbed water molecules and carboxylate groups in the MOFs played an important role in the proton conduction process. Our work gives more choice for the design of novel proton conductive MOF materials. [ABSTRACT FROM AUTHOR]

Zeolitic imidazolate framework-8 (ZIF-8) with different sizes and morphologies were successfully synthesized using a membrane dispersion reactor (MDR). The MDR synthesis applied in this paper was expected to be an efficient and economical way to synthesize ZIF materials. [ABSTRACT FROM AUTHOR]

Three new 3D lanthanide-based metal–organic frameworks (MOFs), [Ln2(ImBDC)3(2H2O)]n (where Ln = Tb3+ (1)/Sm3+ (2)/Eu3+ (3), ImBDC = 2-(imidazol-1-yl)terephthalic acid), have been synthesized solvothermally and characterized with single-crystal X-ray diffraction and other physicochemical methods. MOFs1–3 are isostructural and feature a 3D framework structure with 1D channels of dimension 3.91 × 5.27 Å2 decorated with basic imidazole groups. Owing to imidazole functionalized pores, MOF1 exhibits selective adsorption properties for CO2 with a high interaction energy (Qst) of 37.1 kJ mol−1. The activated samples of the MOFs act as efficient heterogeneous catalysts for the cycloaddition reaction of CO2 to epoxides to generate value-added cyclic carbonates. Interestingly, due to the narrow pore channels of the MOFs, preferential conversion of smaller size epoxides over the larger epoxides is observed. Furthermore, the MOF catalyst could be recycled and reused for up to five cycles without significant reduction in the catalytic activity. Thus the present study demonstrates size-selective catalytic activity for the conversion of smaller epoxides to cyclic carbonates under mild reaction conditions. [ABSTRACT FROM AUTHOR]

Recently, cationic metal–organic frameworks (MOFs) have drawn considerable attention in the treatment of wastewater containing toxic anions via anion exchange due to the presence of exchangeable anions in their pores. In this work, we employed the neutral imidazole-containing ligand tris(4-(1H-imidazol-1-yl)phenyl)amine (tipa) to construct two novel cationic MOFs, {[Ag3(tipa)2]4·[Ag(tipa)]·(NO3)13·2CH3CN·20H2O} (1) and {[Zn12(H2O)12(tipa)12(SiF6)9]·(SiF6)2·(OH)2·7CH3CN·64H2O} (2). Structural analysis revealed that complex 1 possessed 3D frameworks constructed from intercrossing 2D wavelike grids and highly disordered 1D chains with free NO3− in the channels, while 2 exhibited 3D frameworks composed of rotaxane-like subunits with free SiF62− and OH− anions filled in the channels. Subsequently, the anion-exchange properties of the two MOFs were examined with Cr2O72−, and the results suggest that only compound 1 exhibited adsorption capacity for Cr2O72− with high efficiency and recyclability. [ABSTRACT FROM AUTHOR]

The present work describes the synthesis of a copper-1H-imidazole metal organic framework (Cu-I MOF) and copper-1H-imidazole@activated carbon metal organic framework (Cu-IC MOF) via a simple chemical route under ultrasonication. The formation of the as-synthesized MOFs was confirmed by various spectral and analytical techniques. The electrochemical properties of the MOFs are examined for supercapacitor applications as an electrode material using Cyclic Voltammetry (CV), Galvanostatic Charge–Discharge (GCD) and Electrochemical Impedance Spectroscopic (EIS) techniques. Comparison of the results obtained from the CV and GCD studies reveals that the Cu-IC MOF has a specific capacitance greater than that of Cu-I, i.e. 753 F g−1 at a scan rate of 5 mV s−1 by CV and 733 F g−1 at a current density of 1 A g−1 by GCD for the Cu-IC MOF while 596 F g−1 by CV and 252 F g−1 by GCD for the Cu-I MOF. The Cu-IC MOF retained about 85% of its initial capacitance even after 2000 GCD cycles at 1 A g−1 current density. This observation proves that the Cu-IC MOF may be a potential electrode material for supercapacitor applications. [ABSTRACT FROM AUTHOR]