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The introduction of molecular rotors with distinct kinetic characteristics into metal–organic frameworks (MOFs) imparts these materials with heightened responsiveness, facilitating precise control over gas molecule recognition, adsorption as well as separation. This enhancement translates into improved performance in separating light hydrocarbons. In this investigation, three MOF materials (In-NDC, SNNU-118, and SNNU-128) were synthesized with two molecular rotor-containing ligands, 1,4-naphthalenedicarboxylic acid (1,4-NDC) and 9,10-anthracenedicarboxylic acid (9,10-ADC). Among these materials, In-NDC and SNNU-118 exist as supramolecular isomers. Through meticulous adjustment of synthesis conditions, successful structural transformations were achieved. Unlike In-NDC, the rotational flexibility of the molecular rotor 1,4-NDC endows SNNU-118 with distinctive adsorption behavior, manifesting as a gate-opening effect induced by the rotation of the molecular rotor. This phenomenon is facilitated by electrostatic repulsion between 1,4-NDC and CO2 during the adsorption process. Additionally, the electrostatic attraction between the framework and C2H2 molecules significantly enhances C2H2 adsorption at low pressure, thereby improving selectivity for C2H2. Compared to In-NDC, the IAST selectivity values increased from 4.55 to 17.05. Dynamic breakthrough experiments demonstrate the effective separation capabilities of both In-NDC and SNNU-118 in separating C2H2/CO2 mixed gases. [ABSTRACT FROM AUTHOR]

Nitrite (NO2−) and hydrazine (N2H4) are common N‐pollutants in groundwater. The electrochemical method can realize the treatment of N‐pollutants and the synthesis of energy substance ammonia (NH3). Designing and synthesizing efficient electrocatalysts is of great significance. Herein, ultrathin Co0.5NiS nanosheets attached on nickel foam (Co0.5NiS‐NSs/NF) are synthesized via cyanogel‐NaBH4 hydrolysis process and succedent sulfurization approach. Owing to the ultrathin nanosheet structure and the interaction between Ni and Co, Co0.5NiS‐NSs/NF exhibits high activity for NO2− reduction reaction (NO2−RR), in which the Faraday efficiency is 92.2% and the NH3 yield is 0.25 mmol h−1 cm−2 at −0.15 V potential. Meanwhile, Co0.5NiS‐NSs/NF also displays remarkable activity for N2H4 oxidation reaction in KOH electrolyte. Therefore, a symmetrical Co0.5NiS‐NSs/NF||Co0.5NiS‐NSs/NF electrolyzer is assembled, which only needs the operating voltage of 0.36 V to reach 10 mA cm−2 for NO2−‐to‐NH3 conversion in the presence of N2H4. This work reports a promising and efficient strategy for NH3 production at a small operating voltage and treatment of the N‐pollutants. [ABSTRACT FROM AUTHOR]

Although MOF-5 and its related family members are landmark metal–organic frameworks (MOFs), they have large specific surface area and high porosity, which have long been a subject regarding their instability. The introduction of new inorganic building blocks, in addition to classical [Zn4O(COO)6], is a promising way to maintain the highly attractive architecture of MOF-5. Herein, a family of new MOF-5-like frameworks were synthesized by using squaric acid (SQ) and transition metal salts, namely, {(NH(CH3)2)2[M4X4(SQ)3]}n (SNNU-505-M, M = Zn, Co and Ni, X = F− and OH−). In this SNNU-505-M series of compounds, except for the μ3-bridging atom of SNNU-505-Zn being an F− ion, all the others are OH−. Compared with MOF-5, SNNU-505-M exhibits good stability in organic solvent and aqueous solutions (pH = 3–13). Furthermore, benefiting from its ultra-micropore size and multiple polarity F−/OH− adsorption sites, SNNU-505-M shows high C2H2 adsorption capacity and excellent separation performance. In particular, SNNU-505-Zn exhibits the best C2H2/C2H4 (1 : 1) separation performance and its breakthrough interval time is 51 min g−1 at 298 K at a flow rate of 2 mL min−1. The GCMC calculations further demonstrate that the excellent C2H2 uptake and C2H2/C2H4 separation performance of SNNU-505-Zn can be mainly attributed to the multiple C–H⋯F hydrogen bonds between the C2H2 molecules and MOF skeleton. [ABSTRACT FROM AUTHOR]