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Metal–organic frameworks (MOFs) exhibit attractive performance in fields such as luminescence sensors and catalysis. We here developed a new MOF ({Cu2(DPQ)2(OBPBI)}n), briefly named Cu-MOF, which has been facilely obtained through the self-assembly of 4, 4′-(quinoxaline-2, 3-diyl)dibenzoic acid (H2DPQ), 1, 1′-[oxybis(4, 1-phenylene)]bis(1H-imidazole) (OBPBI), and CuCl2·2H2O under solvothermal conditions. Cu-MOF contains a paddle-wheel and binuclear copper oxygen cluster unit and forms a 2, 2, 6-connected two-dimensional (2D) net with the point symbol of {42·88·125}{4}2{8}. Luminescence investigations indicate that Cu-MOF has a selective fluorescent response to Fe3+and Cr3+ions in water, with detection limits low to 10–8M, at least three times reusability, and a wide pH applicable scope. A combined logic gate INHIBIT has been built based on the different signal inputs of Fe3+and Cr3+ions and emission intensity signal outputs, providing great potential for distinguishing Fe3+and Cr3+ions. Moreover, Cu-MOF has been successfully applied for the catalytical conversion of CO2to cyclic carbonates under solvent-free and mild conditions (0.1 mol % Cu-MOF, 3 mol % TBAB, 1 atm of CO2, 15 h, 85 °C), with up to 98% yield, 99% selectivity, and three times reusability.

Effective CO2transformations hold essential significance for carbon neutrality and sustainable energy development. Carboxylative cyclization of propargylic amines with CO2serves as an atom-economic reaction to afford oxazolidinones, showing broad applications in organic synthesis and pharmaceutical fields. However, most catalysts involved noble metals, exhibited low efficiency, or required large amounts of base. Hence, it is imperative to explore alternative noble-metal-free catalysts in order to achieve efficient conversion while minimizing the use of additives. Herein, a novel nanopore-based Cu(II)–organic framework (1) based on a new imidazole carboxylic ligand was successfully constructed and exhibited excellent stability. Catalytic investigations revealed that the combination of 1with 1,4-diaza[2.2.2]bicyclooctane (DABCO) efficiently catalyzed the carboxylative cyclization of propargylic amines with CO2, achieving turnover numbers of 142 based on the catalyst and 7.1 based on DABCO. 1as a heterogeneous catalyst maintained high catalytic performance even after being reused at least 5 cycles, with its structure remaining stable. The strong activation of Cu(II) cluster nodes of catalyst 1toward −NH– groups within organic substrates, as demonstrated by mechanism experiments, along with excellent CO2adsorption performance and the presence of regular 1D channels, synergistically facilitates the reaction rate. This research presents the first instance of a Cu(II)–organic framework achieving this cyclization reaction, offering wide prospects for novel catalyst design and CO2utilization.

Efficient and multiple CO2utilization into high-value-added chemicals holds significant importance in carbon neutrality and industry production. However, most catalysis systems generally exhibit only one type of CO2transformation with the efficiency to be improved. The restricted abundance of active catalytic sites or an inefficient utilization rate of these sites results in the constraint. Consequently, we designed and constructed two metal hydrogen-bonded organic frameworks (M-HOFs) {[M3(L3–)2(H2O)10]·2H2O}n(M = Co (1), Ni (2); L = 1-(4-carboxyphenyl)-1H-pyrazole-3,5-dicarboxylic acid) in this research. 1and 2are well-characterized, and both show excellent stability. The networks connected by multiple hydrogen bonds enhance the structural flexibility and create accessible Lewis acidic sites, promoting interactions between the substrates and catalytic centers. This enhancement facilitates efficient catalysis for two types of CO2transformations, encompassing both cycloaddition reactions with epoxides and aziridines to afford cyclic carbonates and oxazolidinones. The catalytic activities (TON/TOF) are superior compared with those of most other catalysts. These heterogeneous catalysts still exhibited high performance after being reused several times. Mechanistic studies indicated intense interactions between the metal sites and substrates, demonstrating the reason for efficient catalysis. This marks the first instance on M-HOFs efficiently catalyzing two types of CO2conversions, finding important significance for catalyst design and CO2utilization.

Metal–organic frameworks (MOFs) show promising applications in catalysis and luminescent sensors due to their unique organic–inorganic porous structure. Herein, a novel copper MOF (Cu-MOF) is architected by the assembly of an imidazole and carboxylic acid functionalized flexible ligand (HIM) with copper ions under hydrothermal conditions. The Lewis acid and base built-in structure of HIM facilitate the architecting of a 2D porous 3-c network with {43} topology during the self-assembled coordination. the Cu-MOF can be used to catalyze the reaction of CO2with epoxides to produce cyclic carbonates with 12 examples of substrate scope in 70–98% yields under mild conditions. The catalyst shows recycling ability and achieves the conversion of cyclic carbonate beyond 90% after 5 cycles. In addition, the Cu-MOF can be developed as a turn-on Fe3+-selective luminescent sensor with a detection limit of 0.53 μM. Moreover, the sensor can selectively recognize MnO4–and Cr2O72–by emission quenching with detection limits of 0.57 and 0.23 μM, respectively. Besides, the sensor shows recycling ability in sensing and can be regenerated and reused 5 times. Therefore, the Cu-MOF exhibits versatility and offers promising applications in catalysis and luminescent sensors.

Metal–organic frameworks attract great attention because they show great potential for applications such as catalysis and luminescence sensing. Herein, a novel copper–organic framework, [Cu2.5(OH)(nia)2(Bibt)1.5]n, known as CuBN, was hydrothermally prepared based on the self-assembly of 4,7-bis(1H-imidazole-1-yl) benzo-[2,1,3]thiadiazole (Bibt), 5-(1,8-naphthalimido)-isophthalic acid (H2nia), and CuCl2·2H2O. CuBNexhibited a 4, 8-connected sqc 3D porous framework with a binuclear copper oxygen cluster unit and the point symbol of {344851264}{324252}. CuBNcan work as an efficient luminescent sensor for Hg2+via a turn-on fluorescence change. Fluorescent data shows that CuBNhas high selectivity to Hg2+among various metal ions, and the detection limit is low, down to 9.52 nM. The turn-on sensing behavior can be mainly attributed to the Hg2+-promoted framework collapsing and subsequent binding to the ligand Bibt. In addition, CuBNexhibits the capability of promoting the chemical fixation of CO2to cyclic carbonates under mild conditions (0.1 mol % catalyst loading, 2 mol % TBAB, 1 atm of CO2, 24 h, 80 °C and without solvent) with up to 97% yield and good reusability.