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Light-responsive adsorbents have attractive application prospects owing to their adjustable performance under light irradiation. Introducing light-responsive azobenzene moieties to a metal–organic framework (MOF) as the backbone of the organic linkers is a significant method to construct light-responsive adsorbents. The modulation of this kind of adsorbent via light irradiation requires maintaining exposure to the illumination with a specific wavelength. Herein, we report a series of light-responsive composites which realize the long-term suppressed bending of light-responsive ligands in the frameworks through short-time light irradiation. An inorganic persistent luminescent material, LiYGeO4:Bi3+, was incorporated into a light-responsive MOF, PCN-250, to fabricate the composites. After ultraviolet irradiation at 254 nm for 10 min, the LiYGeO4:Bi3+ in the composites can provide continuous illumination at 365 nm for at least 6 h. Driven by this illumination, the composites can regulate CO2 adsorption capacity without continuous light irradiation, and the best change amount of the adsorption capacity is up to 14.6%, while that on PCN-250 can be negligible. This work provides a new route to develop light-responsive materials for real-world applications. [ABSTRACT FROM AUTHOR]

Photo-responsive metal–organic frameworks (PMOFs) have great potential in on-demand controllable adsorption processes under distinct light conditions, which is challenging to realize by conventional adsorbents with static frameworks and properties. Here, we report a new type of adsorbent with photo-responsive active sites for adsorptive desulfurization. Coumarin monomers were incorporated in MIL-101(Cr) to construct the photo-responsive adsorbents by coordinating with unsaturated chromium sites. Trigged by UV light (>310 nm), coumarin monomers undergo dimerization to a cyclobutane structure, which forms a conjugation effect with π electrons on the aromatic ring of the sulfur compound, leading to remarkably increased uptake of 4,6-dimethyldibenzothiophene (4,6-DMDBT). Coumarin dimers can transform back to monomers under irradiation of 254 nm UV light, corresponding to decreased adsorption of 4,6-DMDBT. The change in adsorption amount between PMOF and the coumarin monomers and dimers is up to 62.8%. The present study might open up an avenue for the fabrication of adsorbents with on-demand active sites for various applications. [ABSTRACT FROM AUTHOR]

Traditionally chemical modifications altering molecular skeletons (MSs) were the only solution to modulate material active sites at ground states. According to Runge–Gross theorem, the MS and the adjoint electron‐configuration (MS‐AEC) can be tuned at excited states (ESs), even without chemical modifications. A porphyrinic metal–organic framework PCN‐222 and its metalloporphyrin homologs are used for adsorptive carbon capture both at ground states and with photoexcitation (350–780 nm). Instead of passive photothermal effects, the carbon capture performances of all the adsorbents get promotions. The dominant first ESs with long lifetimes meet the time‐scale of molecular adsorption equilibrium, meanwhile tune the MS‐AEC of the porphyrin ligands to generate new active sites with much more negative electrostatic‐potentials, of which the distribution gradient is crucial for inducing CO2 and can be further modulated by the central‐coordinated metal cations at ground and excited states. This work demonstrates the availability of static ESs and possibility of nonchemical modifications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Light‐responsive adsorbents capture significant attention due to their tailorable performance upon light irradiation. The modulation of such adsorbents is mainly based on weak (physical) interactions caused by steric hindrance while tuning strong interaction with target adsorbates is scarce. Here we report smart π‐complexation adsorbents, which can adjust the π‐complexation of active sites via light irradiation. A typical metal‐organic framework, MIL‐101‐NH2, was decorated with azobenzene motifs, and Cu+ as π‐complexation active sites were introduced subsequently. The reversible light‐induced isomerization of azobenzene regulates the surface electrostatic potentials around Cu+ from −0.038 to 0.008 eV, causing shielding and exposure effects. The alteration of CO uptake is achieved up to 54 % via changing light, while that on MIL‐101‐NH2 is negligible. This study provides a clue for designing target‐specific smart materials to meet the practical stimuli‐responsive adsorption demands. [ABSTRACT FROM AUTHOR]

Reproducing the highly efficient catalytic cascade system to mimic life behaviors in vitro has been intensively investigated over the past few decades. However, except for biocatalysis with enzymes, most chemocatalytic cascades in essence combine several reactions that occur over mutually independent catalytic sites in a container. Herein, with a series of control experiments and stepwise theoretical derivation based on the calculations of density functional theory and a semi-empirical method, a generalized cascade catalysis is discovered for the chemocatalytic conversion of CO2 to higher alcohols over a porphyrinic zirconium metal–organic framework, PCN-224-Cu. Two types of catalytic sites in PCN-224-Cu, i.e., the Zr6 cluster and TCPP-Cu unit, act like organelles, which can complete a class of reactions instead of particular one. The Zr6 cluster is in charge of molecular dissociation, while the TCPP-Cu unit is responsible for molecular assembly. Therefore, semi-finished intermediates repeatedly transfer between the two types of catalytic sites until the ultimate formation of ethanol with high efficiency (ethanol yield, 4.53 mmol h−1 gcat.−1 at 403 K) and selectivity (∼100%). [ABSTRACT FROM AUTHOR]

Cu+‐containing materials have great potentials in various applications like adsorptive desulfurization. Nevertheless, their applications are severely obstructed by poor stability of Cu+ in air. Here, we first clarify the mechanism of Cu+ oxidation by first‐principle calculations and demonstrate that moisture accelerates Cu+ oxidation dramatically. Then, the microenvironment of Cu2O‐modified HKUST‐1, a typical metal‐organic framework, is adjusted from hydrophilic to hydrophobic with polydimethylsiloxane coating (producing Cu2O@HK@P). This isolates moisture from pores and enhances the stability of Cu+ significantly even under oxygen atmosphere. Cu+ in Cu2O@HK@P preserves well after exposed to air for 6 months, while Cu2O@HK lose almost all Cu+ for 2 weeks. The optimal Cu2O@HK@P can remove 540 μmol g−1 of thiophene from hydrous fuel, which is much superior to Cu2O@HK (227 μmol g−1) and most reported adsorbents. Our strategy can also be applied to stabilize Cu+ in various materials including zeolite, mesoporous silica, and activated carbon. [ABSTRACT FROM AUTHOR]