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The selectivity control of Pd nanoparticles (NPs) in the direct CO esterification with methyl nitrite toward dimethyl oxalate (DMO) or dimethyl carbonate (DMC) remains a grand challenge. Herein, Pd NPs are incorporated into isoreticular metal–organic frameworks (MOFs), namely UiO‐66‐X (X=‐H, ‐NO2, ‐NH2), affording Pd@UiO‐66‐X, which unexpectedly exhibit high selectivity (up to 99 %) to DMC and regulated activity in the direct CO esterification. In sharp contrast, the Pd NPs supported on the MOF, yielding Pd/UiO‐66, displays high selectivity (89 %) to DMO as always reported with Pd NPs. Both experimental and DFT calculation results prove that the Pd location relative to UiO‐66 gives rise to discriminated microenvironment of different amounts of interface between Zr‐oxo clusters and Pd NPs in Pd@UiO‐66 and Pd/UiO‐66, resulting in their distinctly different selectivity. This is an unprecedented finding on the production of DMC by Pd NPs, which was previously achieved by Pd(II) only, in the direct CO esterification. [ABSTRACT FROM AUTHOR]

A general approach to prepare superhydrophobic MOFs (denoted as MOFs-CF3) through a post-decorating strategy for highly efficient chemical fixation of CO2 was demonstrated. The enhanced catalytic activity of MOFs-CF3 is attributed to a synergistic effect between the Lewis acid sites of MOFs and modification of the electron-withdrawing trifluoromethyl group, which resulted in a high CO2 enrichment capacity. The possible mechanism of cycloaddition catalyzed by the MOFs-CF3 catalyst was also proposed. [ABSTRACT FROM AUTHOR]

A general approach to prepare superhydrophobic MOFs (denoted as MOFs-CF3) through a post-decorating strategy for highly efficient chemical fixation of CO2 was demonstrated. The enhanced catalytic activity of MOFs-CF3 is attributed to a synergistic effect between the Lewis acid sites of MOFs and modification of the electron-withdrawing trifluoromethyl group, which resulted in a high CO2 enrichment capacity. The possible mechanism of cycloaddition catalyzed by the MOFs-CF3 catalyst was also proposed. [ABSTRACT FROM AUTHOR]

Direct and selective oxidation of methane (CH4) into methanol (CH3OH) under ambient conditions remains a grand challenge because of the high energy barrier of CH4 activation and the complicated processes involved. Herein, by incorporating AuPd alloy nanoparticles (NPs) into a series of Cu2+-doped metal–organic frameworks (MOFs), namely AuPd@Cu-UiO-66x, efficient and direct catalytic conversion of CH4 to CH3OH can be achieved at mild temperature (70 °C) with H2O2 as an oxidant. The Cu-UiO-66 serving as the microenvironment parameter not only regulates the electronic state of AuPd NPs to improve the CH4 adsorption and activation, but also affects the generation of hydroxyl radicals (˙OH) in H2O2 reaction pathways, which consequently results in a volcano-type dependency of the CH3OH selectivity on the Cu contents. This work represents the first finding on achieving direct catalytic oxidation of CH4 to CH3OH under mild conditions by modulating the microenvironment of catalytic centers based on a MOF platform. [ABSTRACT FROM AUTHOR]

The chemical microenvironment modulation of metal nanoparticles (NPs) holds promise for tackling the long‐lasting challenge of the trade‐off effect between activity and selectivity in catalysis. Herein, ultrafine PdCu2 NPs incorporated into covalent organic frameworks (COFs) with diverse groups on their pore walls have been fabricated for the semihydrogenation of alkynes. The Cu species, as the primary microenvironment of Pd active sites, greatly improves the selectivity. The functional groups as the secondary microenvironment around PdCu2 NPs effectively regulate the activity, in which PdCu2 NPs encapsulated in the COF bearing −CH3 groups exhibit the highest activity with >99 % conversion and 97 % selectivity. Both experimental and calculation results suggest that the functional group affects the electron‐donating ability of the COFs, which successively impacts the charge transfer between COFs and Pd sites, giving rise to a modulated Pd electronic state and excellent catalytic performance. [ABSTRACT FROM AUTHOR]

The exposed facets of supported catalysts play a crucial role in catalysis; however, they are usually ignored and related studies remain rare. Herein, we have fabricated a series of sandwich‐structured metal–organic framework composites, denoted ZIF‐8X@Pd@ZIF‐8 (x represents the morphology of ZIF‐8 core, i.e. ZIF‐8C exposing (100) facet, ZIF‐8RD exposing (110) facet, and ZIF‐8TRD exposing mixed (100) and (110) facets), featuring Pd nanoparticles deposited on the specific crystal facets of ZIF‐8 core, for hydrogenation of p‐chloronitrobenzene. The Pd electronic state is tailored by the ZIF‐8 core, where more electron‐deficient Pd is found in ZIF‐8C@Pd@ZIF‐8 than that in ZIF‐8RD@Pd@ZIF‐8, leading to discriminative adsorption of the −NO2 and −Cl groups of p‐chloronitrobenzene. Consequently, ZIF‐8C@Pd@ZIF‐8 exhibits excellent activity (97.6 %) and selectivity (98.1 %) to p‐chloroaniline. This work highlights crystal facet engineering of supports to modulate the microenvironment and electronic state of supported metal nanoparticles, offering a promising avenue to enhanced catalysis. [ABSTRACT FROM AUTHOR]

Charge transfer between metal sites and supports is crucial for catalysis. Redox‐inert supports are usually unfavorable due to their less electronic interaction with metal sites, which, we demonstrate, is not always correct. Herein, three metal–organic frameworks (MOFs) are chosen to mimic inert or active supports for Pt nanoparticles (NPs) and the photocatalysis is studied. Results demonstrate the formation of a Schottky junction between Pt and the MOFs, leading to the electron‐donation effect of the MOFs. Under light irradiation, both the MOF electron‐donation effect and Pt interband excitation dominate the Pt electron density. Compared with the "active" UiO‐66 and MIL‐125 supports, Pt NPs on the "inert" ZIF‐8 exhibit higher electron density due to the higher Schottky barrier, resulting in superior photocatalytic activity. This work optimizes metal catalysts with non‐reducible supports, and promotes the understanding of the relationship between the metal–support interaction and photocatalysis. [ABSTRACT FROM AUTHOR]

Keywords: Heterogeneous Catalysis; Lewis Acid Sites; Metal–Organic Frameworks; Microenvironment Modulation; PalladiumHeterogeneous Catalysis. In their Research Article (e202311625), Weijie Yang, Hai‐Long Jiang et al. incorporate Pd nanoparticles into MOFs. The obtained catalyst exhibits high selectivity for dimethyl carbonate in the direct CO esterification with methyl nitrite...By Shuaishuai Hu; Chenfan Xie; Yu‐Ping Xu; Xuelu Chen; Ming‐Liang Gao; He Wang; Weijie Yang; Zhong‐Ning Xu; Guo‐Cong Guo and Hai‐Long JiangReported by Author; Author; Author; Author; Author; Author; Author; Author; Author; Author [Extracted from the article]

A novel strategy has been developed to construct a highly stable core–shell MOF@COF (PCN-222-Co@TpPa-1) bifunctional catalyst through strong π–π stacking interaction. This hybrid material with spatially isolated antagonistic acid–base sites can effectively catalyze the deacetalization–Knoevenagel condensation cascade reaction. [ABSTRACT FROM AUTHOR]

A stable fluorescent nanofibrous membrane was fabricated by in situ growing Eu-MOF crystals on electrospun polyacrylonitrile nanofibers modified with γ-aminobutyric acid. This nanofibrous membrane can be used as a convenient fluorescent test paper for rapid and cyclic detection of nitrobenzene. [ABSTRACT FROM AUTHOR]

Bat algorithm (BA) is a new meta-heuristic optimization algorithm that is inspired by the echolocation characteristics of bats with varying pulse rates of emission and loudness. BA has been proven to be a powerful tool in solving a wide range of global optimization problems. In this study, visual tracking is considered to be a process of searching for target by various bats in sequential images. A BA-based tracking architecture is proposed and the sensitivity and adjustment of the parameters in BA are studied experimentally. To demonstrate the tracking ability of the proposed tracker, comparative studies of tracking accuracy and speed of the BA-based tracker with three representative trackers, namely, particle filter, meanshift and particle swarm optimization are presented. Comparative results show that the BA-based tracker outperforms the other three trackers. [ABSTRACT FROM AUTHOR]

Particle filter algorithm has been proven to be a powerful tool in solving visual tracking problems. However, the problem of sample impoverishment which is brought by the procedure of re-sampling is a main handicap of the particle filter. In this work, an improved particle filter based on firefly algorithm is proposed to solve this problem. The particles in the particle filter are optimized using firefly algorithm before re-sampling. Thus, the number of meaningful particles can be increased, and the particles can approximate the true state of the target more accurately. Experimental results on visual tracking show that the proposed algorithm outperforms the standard particle filter and it can track targets robustly in various challenging conditions. [ABSTRACT FROM AUTHOR]

An InIII-based anionic framework (InIII-MOF) with 4-connected SrAl2 topology was constructed. The InIII-MOF with permanent porosity functions as a host for encapsulation of Ln3+ ions through ion-exchange processes. The photophysical properties of the as-prepared Ln3+@InIII-MOF were investigated and the results showed that the InIII-MOF could serve as an antenna to sensitize Ln3+ cations, especially suitable for Tb3+ and Eu3+ ions. The possible sensitization mechanism has been studied by surface photovoltage spectroscopy. Additionally, the InIII-MOF could also act as a host material when applied in the separation and purification of cationic dyes, which is highly based on the size and charge of organic dyes. Moreover, it can be used as a chromatographic column stationary phase to separate cationic dyes more efficiently and selectively. It is believed that the as-prepared InIII-MOF may have potential applications in optical materials and environmental fields. [ABSTRACT FROM AUTHOR]

Firefly algorithm (FA) is a new meta‐heuristic optimisation algorithm that mimics the social behaviour of fireflies flying in the tropical and temperate summer sky. In this study, a novel application of FA is presented as it is applied to solve tracking problem. A general optimisation‐based tracking architecture is proposed and the parameters' sensitivity and adjustment of the FA in tracking system are studied. Experimental results show that the FA‐based tracker can robustly track an arbitrary target in various challenging conditions. The authors compare the speed and accuracy of the FA with three typical tracking algorithms including the particle filter, meanshift and particle swarm optimisation. Comparative results show that the FA‐based tracker outperforms the other three trackers. [ABSTRACT FROM AUTHOR]

While supported metal nanoparticles (NPs) have shown significant promise in heterogeneous catalysis, precise control over their interaction with the support, which profoundly impacts their catalytic performance, remains a significant challenge. In this study, Pt NPs are incorporated into thioether‐functionalized covalent organic frameworks (denoted COF‐Sx), enabling precise control over the size and electronic state of Pt NPs by adjusting the thioether density dangling on the COF pore walls. Notably, the resulting Pt@COF‐Sx demonstrate exceptional selectivity (> 99 %) in catalytic hydrogenation of p‐chloronitrobenzene to p‐chloroaniline, in sharp contrast to the poor selectivity of Pt NPs embedded in thioether‐free COFs. Furthermore, the conversion over Pt@COF‐Sx exhibits a volcano‐type curve as the thioether density increases, due to the corresponding change of accessible Pt sites. This work provides an effective approach to regulating the catalysis of metal NPs via their microenvironment modulation, with the aid of rational design and precise tailoring of support structure. [ABSTRACT FROM AUTHOR]

Abstract: A theoretical method for investigating the inter-relation between electronic and the molecular structures of a d4 ion in a tetragonal ligand-field has been established on the basis of 210×210 complete energy matrix within a weak-field-representation. Using the method, the local structure parameters of CdGa2S4:Cr2+ system are determined by the experimental EPR zero-field splitting (ZFS) spectra. Our results show that the local structure around Cr2+ is a compression distortion and the local lattice structure parameters R =2.46Å and θ =57.63° are determined. Moreover, the contributions of the spin singlets to ZFS parameters of Cr2+ ions in CdGa2S4 crystals are investigated for the first time. The results indicate that the spin singlets contributions to ZFS parameter D are negligible, but the contributions to ZFS parameters a and F cannot be neglected. [Copyright &y& Elsevier]

While metal nanoparticles (NPs) have demonstrated their great potential in catalysis, introducing chiral microenvironment around metal NPs to achieve efficient conversion and high enantioselectivity remains a long-standing challenge. In this work, tiny Rh NPs, modified by chiral diene ligands (Lx) bearing diverse functional groups, are incorporated into a covalent organic framework (COF) for the asymmetric 1,4-addition reactions between arylboronic acids and nitroalkenes. Though Rh NPs hosted in the COF are inactive, decorating Rh NPs with Lx creates the active Rh-Lx interface and induces high activity. Moreover, chiral microenvironment modulation around Rh NPs by altering the groups on chiral diene ligands greatly optimizes the enantioselectivity (up to 95.6% ee). Mechanistic investigations indicate that the formation of hydrogen-bonding interaction between Lx and nitroalkenes plays critical roles in the resulting enantioselectivity. This work highlights the significance of chiral microenvironment modulation around metal NPs by chiral ligand decoration for heterogeneous asymmetric catalysis., (© 2024 Wiley‐VCH GmbH.)

Inspired by enzymatic catalysis, it is crucial to construct hydrogen-bonding-rich microenvironment around catalytic sites; unfortunately, its precise construction and understanding how the distance between such microenvironment and catalytic sites affects the catalysis remain significantly challenging. In this work, a series of metal-organic framework (MOF)-based single-atom Ru 1 catalysts, namely, Ru 1 /UiO-67-X (X = -H, - m -(NH 2 ) 2 , - o -(NH 2 ) 2 ), have been synthesized, where the distance between the hydrogen-bonding microenvironment and Ru 1 sites is modulated by altering the location of amino groups. The -NH 2 group can form hydrogen bonds with H 2 O, constituting a unique microenvironment that causes an increased water concentration around the Ru 1 sites. Remarkably, Ru 1 /UiO-67- o -(NH 2 ) 2 displays a superior photocatalytic hydrogen production rate, ∼4.6 and ∼146.6 times of Ru 1 /UiO-67- m -(NH 2 ) 2 and Ru 1 /UiO-67, respectively. Both experimental and computational results suggest that the close proximity of amino groups to the Ru 1 sites in Ru 1 /UiO-67- o -(NH 2 ) 2 improves charge transfer and H 2 O dissociation, accounting for the promoted photocatalytic hydrogen production.

The selectivity control of Pd nanoparticles (NPs) in the direct CO esterification with methyl nitrite toward dimethyl oxalate (DMO) or dimethyl carbonate (DMC) remains a grand challenge. Herein, Pd NPs are incorporated into isoreticular metal-organic frameworks (MOFs), namely UiO-66-X (X=-H, -NO 2 , -NH 2 ), affording Pd@UiO-66-X, which unexpectedly exhibit high selectivity (up to 99 %) to DMC and regulated activity in the direct CO esterification. In sharp contrast, the Pd NPs supported on the MOF, yielding Pd/UiO-66, displays high selectivity (89 %) to DMO as always reported with Pd NPs. Both experimental and DFT calculation results prove that the Pd location relative to UiO-66 gives rise to discriminated microenvironment of different amounts of interface between Zr-oxo clusters and Pd NPs in Pd@UiO-66 and Pd/UiO-66, resulting in their distinctly different selectivity. This is an unprecedented finding on the production of DMC by Pd NPs, which was previously achieved by Pd(II) only, in the direct CO esterification., (© 2023 Wiley-VCH GmbH.)

A general approach to prepare superhydrophobic MOFs (denoted as MOFs-CF 3 ) through a post-decorating strategy for highly efficient chemical fixation of CO 2 was demonstrated. The enhanced catalytic activity of MOFs-CF 3 is attributed to a synergistic effect between the Lewis acid sites of MOFs and modification of the electron-withdrawing trifluoromethyl group, which resulted in a high CO 2 enrichment capacity. The possible mechanism of cycloaddition catalyzed by the MOFs-CF 3 catalyst was also proposed.

The chemical microenvironment modulation of metal nanoparticles (NPs) holds promise for tackling the long-lasting challenge of the trade-off effect between activity and selectivity in catalysis. Herein, ultrafine PdCu 2 NPs incorporated into covalent organic frameworks (COFs) with diverse groups on their pore walls have been fabricated for the semihydrogenation of alkynes. The Cu species, as the primary microenvironment of Pd active sites, greatly improves the selectivity. The functional groups as the secondary microenvironment around PdCu 2 NPs effectively regulate the activity, in which PdCu 2 NPs encapsulated in the COF bearing -CH 3 groups exhibit the highest activity with >99 % conversion and 97 % selectivity. Both experimental and calculation results suggest that the functional group affects the electron-donating ability of the COFs, which successively impacts the charge transfer between COFs and Pd sites, giving rise to a modulated Pd electronic state and excellent catalytic performance., (© 2023 Wiley-VCH GmbH.)

Charge transfer between metal sites and supports is crucial for catalysis. Redox-inert supports are usually unfavorable due to their less electronic interaction with metal sites, which, we demonstrate, is not always correct. Herein, three metal-organic frameworks (MOFs) are chosen to mimic inert or active supports for Pt nanoparticles (NPs) and the photocatalysis is studied. Results demonstrate the formation of a Schottky junction between Pt and the MOFs, leading to the electron-donation effect of the MOFs. Under light irradiation, both the MOF electron-donation effect and Pt interband excitation dominate the Pt electron density. Compared with the "active" UiO-66 and MIL-125 supports, Pt NPs on the "inert" ZIF-8 exhibit higher electron density due to the higher Schottky barrier, resulting in superior photocatalytic activity. This work optimizes metal catalysts with non-reducible supports, and promotes the understanding of the relationship between the metal-support interaction and photocatalysis., (© 2022 Wiley-VCH GmbH.)

Herein, we reported a facile strategy for the preparation of trifunctional ionic metal-organic frameworks (MOFs) incorporating imidazolium cation functionalities. This strategy exploits the Debus-Radziszewski reaction to create the cationic imidazole ring by postsynthetic modification, meanwhile introducing exchangeable counteranions. On the basis of this strategy, MIL-101-IMOH-Br - has been synthesized, which combines Lewis acidic sites, Brønsted acidic sites, and nucleophilic centers to achieve catalysis for the carbon dioxide-epoxide cycloaddition into cyclocarbonate without any cocatalyst and solvent.

A series of 12-connected lanthanide cluster based metal-organic frameworks (MOFs) have been constructed by [Ln 6 (μ 3 -OH) 8 (COO-) 12 ] secondary building units (SBUs) and 2-aminobenzenedicarboxylate (BDC-NH 2 ) ligands. These obtained materials exhibit high chemical stability and generic thermal stability, especially in acidic and basic conditions. They also present commendable CO 2 adsorption capacity, and Yb-BDC-NH 2 was further confirmed by a breakthrough experiment under both dry and wet conditions. Moreover, these materials possess both Lewis acid and Brønsted base sites that can catalyze one-pot tandem deacetalization-Knoevenagel condensation reactions.

Two hexanuclear Ln(III) cluster-based metal-organic frameworks (MOFs) (Ln = Tb or Eu) and a series of isomorphic bimetallic Ln(III)-MOFs have been synthesized by changing the ratio of Tb(III) and Eu(III) under solvothermal conditions. The excellent linear color tunability (from green to red) makes them suitable for barcode application. In addition, the anionic Ln(III)-MOFs exhibit superior uptake capacity toward methylene blue (MB + ) by an ion-exchange process, and its reversible adsorption performance makes 1 suitable for removal of organic dye MB + . The as-prepared anionic hexanuclear Ln(III) cluster-based MOFs can serve as a multifunctional material for an optical and environmental area.

Spectra with different resolution (1, 2, 4 and 8 cm(-1)) of samples with combined CO/CO2/NO were used to build models for quantitative analysis of each component. Using these models, the influence of spectral resolution on gas quantitative analysis was studied. Research data show that for each component there is a best competent resolution for its quantitative analysis. And the quantitative analysis of all involved components has good calibration accuracy with higher resolution (1/2 cm(-1)) and lower resolution (8 cm(-1)), giving the relatively high mean of correlation coefficient of each component (r) more than 0.999 5, and the mean of root mean square error of calibration (RMSEC) and root mean square error of prediction (RMSEP) of each component below 18.36 and 15.43 respectively, but the calibration accuracy of the model with moderate resolution of 4 cm(-1) dropped sharply, giving the mean of correlation coefficient of each component (r) of 0.989 66,and the mean of root mean square error of calibration (RMSEC) and root mean square error of prediction (RMSEP) of each component of 90.37 and 64.33 respectively. These results demonstrate that the spectral resolution has an important effect on the calibration accuracy of gas quantitative analysis model and the successful application of FTIR As can be seen, the accuracy of gas quantitative analysis is highly dependent on the proper selection of spectral resolution. In order to improve the accuracy of gas quantitative analysis, it is very important to select suitable spectral resolution depending on different components and various application situations.