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Lanthanide metal–organic frameworks (Ln-MOFs) combine the lanthanide luminescence characteristics and the advantages of porous materials, which can be used in various research fields by exploring their multifunctional properties. A three-dimensional water-stable and high-temperature resistant Eu-MOF [Eu(H2O)(HL)]·0.5MeCN·0.25H2O (H4L = 4-(3,5-dicarboxyphenoxy)isophthalic acid), demonstrating a high photoluminescence quantum yield, was synthesized and structurally characterized. In terms of luminescence, the Eu-MOF exhibits excellent selectivity and quenching sensing for Fe3+ (LOD = 4.32 μM) and ofloxacin, as well as color modulation with Tb3+ and La3+ to develop white LED components with high illumination efficiency (color rendering index, CRI = 90). On the other hand, narrow one-dimensional channels of the Eu-MOF decorated with COOH groups enable a rare reverse adsorption selectivity in a CO2/C2H2 gas mixture. In addition, the protonated carboxyl groups in the Eu-MOF provide an efficient conducting platform for proton transfer with a conductivity value of 8 × 10−4 S cm−1 at 50 °C and RH 100%. [ABSTRACT FROM AUTHOR]

Porous materials such as MOFs are interesting candidates for gas separation and storage. An important parameter to gain deeper insights to the adsorption process of an adsorptive on an adsorbent is the isosteric enthalpy of adsorption, ΔHads which is defined as the heat to be released/required when an adsorptive binds to/detaches from the solid surface of an adsorbent. Two or three adsorption isotherms at different but close temperatures with ΔT ≤ 20 K for two and ΔT ≈ 10 K for three isotherms are the basis to derive the isosteric enthalpy of adsorption through the Clausius–Clapeyron approach or the virial analysis. This Perspective presents the procedure of the common (dual-site) Freundlich–Langmuir fit/Clausius–Clapeyron approach and the virial fit of the isotherms with usable Excel sheets and Origin files for the subsequent derivation of ΔHads. Exemplary adsorption isotherms of CO2, SO2 and H2 at two temperatures on MOFs are analyzed. The detailed computational description and comparison of the Clausius–Clapeyron approach and the virial analysis to determine ΔHads outlines the limitations of the two methods with respect to the available experimental data, especially at low pressure/low uptake values. It is emphasized that no extrapolation beyond the experimental data range should be done. The quality of the important and underlying isotherm fits must be checked and ensured with logarithmic-scale n/p isotherm plots for the (dual-site) Freundlich–Langmuir fit in the low-pressure region and through low standard deviations for the coefficients in the virial analysis. [ABSTRACT FROM AUTHOR]

The formation of metal–organic frameworks (MOFs) under given reaction conditions depends on various factors including reaction duration, temperature, used solvent, system pH, and others. Among them, the reaction duration is relatively less investigated. In this work, based on a Cu(ii)-MOF system, the reaction duration was found to play an important role in directing the formation of two different products, (NH2(CH3)2)[Cu12(DDPN)6(H2O)10Cl] (BUT-301) on shorter reaction time and (NH2(CH3)2)2[Cu(DDPN)] (BUT-302) on longer reaction time, when CuCl2 reacted with 3,5-di(3,5-dicarboxylphenyl)nitrobenzene (H4DDPN) in a DMA/MeOH mixed solvent at 120 °C. With increasing the reaction duration, BUT-301 can transform into BUT-302. Both MOFs have three-dimensional (3D) framework structures. BUT-301 is constructed from paddle-wheel Cu2(COO)4 units and DDPN4– ligands as four-connected linkers, while BUT-302 is assembled from mononuclear Cu(ii) centers connecting the ligands as also four-connected linkers but in a monodentate coordination fashion. N2 adsorption confirmed that both MOFs are porous materials with the Brunauer–Emmett–Teller (BET) surface areas of 1953 and 561 m2 g−1, respectively. Interestingly, both BUT-301 and -302 show selective adsorption properties of C3H4 over C3H6. The C3H4/C3H6 adsorption selectivities were calculated to be 1.9 and 4.4 at 0.1 bar and 298 K by the ideal adsorbed solution theory (IAST) for a 1 : 99 C3H4/C3H6 mixture, respectively. [ABSTRACT FROM AUTHOR]

A new three-dimensional (3D) porous Mn(ii)-based metal–organic framework [Mn4(L)2(H2O)4]n·4DMF·H2O (1) has been synthesized using Mn(ii) and the rigid 2,6-di(2′,5′-dicarboxylphenyl)pyridine (H4L) ligand under solvothermal conditions. Structural analysis revealed that MOF 1 is an open framework with exposed active nitrogen atoms and rectangular-shaped channels along the b axis (with effective aperture sizes of 11.3 × 8.8 Å2 and 10.7 × 8.7 Å2). Gas sorption behaviors showed that MOF 1 has a relatively high capacity and selectivity for CO2 over CH4. Thus, the CO2 cycloadditions were studied using different epoxides, displaying the high efficiency of the catalyst. It was also found that MOF 1 shows rapid adsorption for the organic dyes. Therefore, MOF 1 should be explored as a multifunctional porous material for gas separation, catalysis and dye adsorption. [ABSTRACT FROM AUTHOR]