Photoresponsiveness of materials is critical to their tunability and efficiency in terminal applications. Photoresponsive metal-organic polyhedra (PMOPs) feature intrinsic pores and remote controllability, but aggregation of PMOPs in solid state hampers their photoresponsiveness seriously. Herein, we report the construction of a new PMOP (Cu₂₄(C₁₆H₁₂N₂O₄)₁₂(C₁₈H₂₂O₅)₁₂, denoted as MOP-PR-LA), where long alkyl (LA) chains act as the intermolecular poles, propping against adjacent PMOP molecules to create individual microenvironment benefiting the isomerization of photoresponsive (PR) moieties. Upon ultraviolet (UV)- and visible-light irradiation, MOP-PR-LA is much easier to isomerize than the counterpart MOP-PR without LA. For propylene adsorption, MOP-PR has a low change of adsorption capacity (9.9%), while that of MOP-PR-LA reaches 58.6%. Density functional theory calculations revealed that PR in the cis state has a negative effect on adsorption, while the trans state of PR favors adsorption. This work might open an avenue for the construction of photoresponsive materials with high responsiveness and controllability.

Solid strong base catalysts have received considerable attention in various organic reactions due to their facile separation, neglectable corrosion, and environmental friendliness. Although great progress has been made in the preparation of solid strong base catalysts, it is still challenging to avoid basic sites aggregation on support and active sites loss in reaction system. Here, we report a tandem redox strategy to prepare Na single atoms on graphene, producing a new kind of solid strong base catalyst (Na₁/G). The base precursor NaNO₃ was first reduced to Na₂O by graphene (400 °C) and successively to single atoms Na anchored on the graphene vacancies (800 °C). Owing to the atomically dispersed of basicity, the resultant catalyst presents high activity toward the transesterification of methanol and ethylene carbonate to synthesize dimethyl carbonate (turnover frequency (TOF) value: 125.7 h⁻¹), which is much better than the conventional counterpart Na₂O/G and various reported solid strong bases (TOF: 1.0–90.1 h⁻¹). Furthermore, thanks to the basicity anchored on graphene, the Na₁/G catalyst shows excellent durability during cycling. This work may provide a new direction for the development of solid strong base catalysts.

Photo-switchable metal-organic frameworks (PMOFs) as energy-saving adsorbents for tailorable guest capture show admirable potentials for various applications like adsorptive desulfurization. However, the regulation behavior of most reported PMOFs is based on weak physical interaction, and it is highly desired to introduce specific active sites to satisfy the demand of higher adsorption capacity and selectivity. Herein, for the first time, we prepared the PMOFs, azobenzene-functionalized HKUST-1 (HK-Azo), simultaneously decorated with Cu₂O active sites that possess strong interaction with guest molecules. Due to π-complexation interaction of Cu⁺ with aromatic sulfur compounds, the obtained HK-Azo shows obviously higher adsorption capacity on benzothiophene compared with HKUST-1. Upon ultraviolet (UV) and visible irradiation, azobenzene moieties in the PMOFs can transform their configuration freely and reversibly. Such trans/cis isomerization of azobenzene causes exposure/shelter of Cu₂O active sites, leading to controllable benzothiophene capture. The HK-Azo exhibits the change of benzothiophene uptake up to 29.7% upon trans and cis isomerization, which is obviously higher than HKUST-1 with negligible change. This work may inspire the development of new adsorption process regulated by light for adsorptive desulfurization that is impossible to realize by conventional PMOFs.

Ordered porous solid strong bases (OPSSBs) have attracted great research interest due to the excellent performance as heterogeneous catalysts in various reactions. The main obstacle for fabricating OPSSBs is the requirement of high temperature to produce strong basicity on ordered porous materials. For example, the temperatures of 600–650 °C are required for the decomposition of base precursor NaNO₃ to basic sites on mesoporous silica SBA-15 and zeolite Y. Such high decomposition temperatures are energy-intensive and harmful to the structure of supports. Herein, we report the fabrication of OPSSBs by utilizing the redox interaction between base precursor and low-valence metal centers (e.g., Cr³⁺) in metal-organic frameworks (MOFs). The base precursor NaNO₃ on MIL-101(Cr) can be converted to basic sites entirely at 300 °C, which is quite lower than those of the conventional thermal conversion on SBA-15 and zeolite Y (600–650 °C). The exploration on decomposition mechanism reveals that the valence change of Cr³⁺ to Cr⁶⁺ takes place during the conversion of NaNO₃ to basic sites. In this way, MOFs-derived base catalysts have been synthesized successfully by the host–guest redox strategy and exhibit high catalytic activity in typical base-catalyzed reactions.

With the carbonization at an elevated temperature, high aromaticity of a precursor for porous carbons was traditionally thought to be crucial for the resultant perfect textural properties and ideal application performances of the porous carbons. Thus, many efforts have been done to search or to artificially prepare the polymer precursors with higher aromaticity to generate more satisfying porous carbons. However, an antiempirical case was found in this study. The copolymerization between 1,3,5-tris(chloromethyl)-2,4,6-trimethylbenzene (TCM) and cyclohexane-1,4-diamine was successfully implemented to get a polymer code-named NUT-40, in which half of the ring structures are nonaromatic, while N-doped porous carbons (NDPCs) with better textural properties (e.g., S_BET = 1363 m² g⁻¹ for NDPC-600) and competitive CO₂ capture abilities (e.g., CO₂ capacity = 4.3 mmol g⁻¹ at 25 ℃ and 1 bar for NDPC-600) were generated from the NUT-40, compared with the NDPC counterparts derived from the NUT-4 in a previous study (e.g., S_BET = 958 m² g⁻¹ and CO₂ capacity = 3.8 mmol g⁻¹ at 25 ℃ and 1 bar for NDPC-600), in which TCM and ursol were employed as the monomers instead, and thus the ring structures in the NUT-4 was fully aromatic. With first-principle and molecular dynamics simulations, it was demonstrated that the embryo pore structure in the NUT-40 molecule can be more easily maintained during the carbonization than that of the NUT-4, which finally improves the surface area and porosity of the NUT-40 generated NDPCs.