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The synthesis of cyclic carbonates through cycloaddition reactions between epoxides and carbon dioxide (CO2) is an important industrial process. Metal-Organic Frameworks (MOFs) have functional and ordered pore structures, making them attractive catalysts for converting gas molecules into valuable products. One approach to enhance the catalytic activity of MOFs in CO2 cycloaddition reactions is to create open metal sites within MOFs. In this study, the amino-functionalized rare earth Gd-MOF (Gd-TPTC-NH2) and its ionic liquid composite catalysts (Gd-TPTC-NH-[BMIM]Br) were synthesized using 2'-amino-[1,1':4',1"-terphenyl]-3,3",5,5"-tetracarboxylic acid (H4TPTC-NH2) as the ligand. The catalytic performance of these two catalysts was observed in the cycloaddition reaction of CO2 and epoxides. Under the optimized reaction conditions, Gd-TPTC-NH-[BMIM]Br can effectively catalyze the cycloaddition reaction of a variety of epoxide substrates with good to excellent yields of cyclic carbonate products. Comparatively, epichlorohydrin and epibromohydrin, which possess halogen substituents, promote higher yields of cyclic carbonates due to the electron-withdrawing nature of Cl and Br substituents. Additionally, the Gd-TPTC-NH- [BMIM]Br catalyst demonstrated good recyclability and reproducibility, maintaining its catalytic activity without any changes in its structure or properties after five reuse cycles. [ABSTRACT FROM AUTHOR]

A series of highly reduced Mo red clusters {Mo28} (1), {Mo30} (2), and {Mo40} (3) are synthesized from the rational assembly of planar {MoV4} building blocks and employed for proton conduction. 3 exhibits the best conductivity of 7.56 × 10-3 S cm-1 under optimal conditions due to the most efficient hydrogen-bonding network. [ABSTRACT FROM AUTHOR]

Incorporating catalytic units into a crystalline porous matrix represents a facile way to build high-efficiency heterogeneous catalysts, and by rational design of the porous skeleton with appropriate building blocks the catalytic performance can be significantly enhanced for a series of organic transformations owing to the synergistic effect from the multicomponent and confined porous microenvironment around catalytically active sites. Herein, we demonstrate that the design and synthesis of a porous polyoxometalate-based metal–organic framework YL2(H2O)2[CrMo6O18(PET)2]·4H2O (POMOF-1) constructed from Anderson-type [CrMo6O18(PET)2] (PET = pentaerythritol), which can be employed as a multifunctional platform for synthesis of N-containing compounds via selective oxidative coupling with amines. POMOF-1 features microporous 1D channels defined by Y3+ and L, with [CrMo6O18(PET)2] arranged orderly between adjacent Lvia electrostatic interactions. Upon using POMOF-1 as a catalyst and H2O2 as an oxidant, a variety of amines could be effectively converted to value-added amides, imines and azobenzenes via the oxidative cross-coupling with alcohols or homo-coupling. In particular, POMOF-1 showed dramatically improved activity for the N-formylation reaction owing to the synergistic and confinement effect, with the yield of amides up to 95% and 4 times higher than that of homogeneous [CrMo6O18(PET)2]. Meanwhile, the oxidative homo-coupling of arylmethylamines and arylamines can be facilely tuned by adjustment of the amount of oxidant, solvent and additive, affording imines and azobenzenes in high selectivity and yield, respectively. POMOF-1 is robust and can be reused for 5 cycles with little loss of catalytic activity and structural integrity. The work demonstrates that the combination of catalytically active POMs with crystalline porous MOFs holds great potential to build robust and recyclable heterogeneous systems with enhanced activity and selectivity for multifunctional catalysis. [ABSTRACT FROM AUTHOR]

The modulation of selectivity of transfer hydrogenation of alkynes to E-alkenes using formic acid is a challenge due to the limited knowledge of the complex reaction network, including oxidative addition, decarboxylation, reductive elimination, Z→E isomerization, and β-H elimination. Here, the search for the reaction pathway and experiment explorations revealed that the selectivity of Pd(PMe3)4-catalyzed hydrogenation of 1-phenyl-1-propyne to (E)-1-phenylpropene is controlled by the water content in the aqueous solution of formic acid and the reaction time. The combination of an automatic reaction pathway search and density functional theory (DFT) calculations found that the intermolecular hydrogen bonds with water molecules have an influence on lowering the free energy activation barrier of transition states in the oxidative addition steps. The reasonable reaction barriers of Z→E isomerization and hydrogenation result in the dependence of selectivity on reaction time, which has been supported by experiments. By using molecular sieves, the water in formic acid is removed, and the yield of the desired (Z)-1-phenylpropene product increases to the highest value (86%) in 5 hours but decreases to 54% when the reaction is run for 16 hours due to the further Z→E isomerization and hydrogenation. In the second stage which starts from (Z)-1-phenylpropene, the yield of (E)-1-phenylpropene decreased from 90% (with 4 Å MS) to 67% in the aqueous solution of formic acid. [ABSTRACT FROM AUTHOR]