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Direct synthesis of dimethyl carbonate (DMC) from CO2 and CH3OH holds significant economic and environmental value. Numerous catalysts have been employed for this reaction, yet further enhancement of its activity requires a deeper understanding of the catalyst's structure–activity relationship and catalytic mechanism. In this study, we utilized structurally well-defined and highly tunable MOF-808 as a research platform. Functionalizing MOF-808 with ethylenediamine (MOF-808-ED) boosted the space time yield of DMC from 3.25 mmol g−1 h−1 to 7.23 mmol g−1 h−1. The experimental results demonstrate that the reaction involves acid–base synergistic catalysis, where an appropriate balance of acid–base site content is crucial for CO2 and CH3OH to produce DMC, as it facilitates the formation of the key intermediates (CH3OCOO*). Additionally, the nucleophilicity of N is stronger than that of O, further promoting the catalyst's enrichment and activation of CO2. Finally, employing in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) testing, we elucidated the mechanism by which the MOF-808-ED catalyst, with –NH2 as base sites and Zr as acid sites, facilitates the synergistic catalysis of the reaction. This study provides insights into the synergistic effects of acid–base sites on the synthesis of DMC from CO2 and methanol, offering valuable guidance for the development of high-performance catalysts. [ABSTRACT FROM AUTHOR]

Scintillators are essential in converting ionizing X‐rays and γ‐rays into visible light, with applications in medical diagnosis, security inspection, and non‐invasive detection. However, current scintillating materials exhibit unclear structure–function relationships. The performance of scintillators is intricately linked to their electronic band structure, particularly the intrinsic properties of excited states. Therefore, investigating the structural factors affecting scintillation performance is crucial for developing new scintillators. Therefore, Ba‐SMOF 1 ([Ba2(PyTS)(CH3OH)2(H2O)4]n) is synthesized using a pyrene‐based organic motif and metal Ba(II) ions, where PyTS4− refers to pyrene‐1,3,6,8‐tetrasulfonate. For the first time, the excited state of a pyrene‐based X‐ray scintillating metal–organic framework (MOF) is determined through comprehensive all‐electron excitation studies, including in situ experimental electron density and wave‐function analysis. The electron density maps exhibit a continuous overlap, attributed to the associative exciton behaviors among the closely packed PyTS4− linkers. These linkers are identified as the sources of both static and dynamic excimer emissions. The electron density studies reveal the role of excimers in pyrene‐based luminophores, highlighting that interchromophoric interactions are key to enhancing the performance of scintillating MOFs. This discovery opens new avenues for the practical application of scintillating MOFs. [ABSTRACT FROM AUTHOR]

Nonlinear optical (NLO) materials are of immense scientific and technological importance. However, debate has long prevailed theoretically regarding the structural origin of the second harmonic generation (SHG) effect. In this work, the experimental electron density (ED) of controversial β‐BaB2O4 (BBO) is studied by high‐resolution X‐ray diffraction, indicating that the [B3O6]3− motif dominates two large non‐zero SHG tensors (d222 and d311) while Ba atoms contribute mostly to the smallest one (d333), and the atomic SHG contributions of terminal O atoms in [B3O6]3− motifs are much larger than those of B and bridged O atoms, clarifying the disputes on its NLO response mechanism. Besides, the contraction of inner electron shells (5s25p6) of the Ba atom and partial covalent behavior of the Ba─O interaction are first observed experimentally. Furthermore, the SHG coefficients of BBO derived from experimental ED are in excellent agreement with those from bulk crystals, providing a high‐efficient and low‐cost method of screening high‐performance NLO materials with just an easy‐to‐obtain tiny crystal. [ABSTRACT FROM AUTHOR]

The study of facile‐synthesis and low‐cost X‐ray scintillators with high light yield, low detection limit and high X‐ray imaging resolution plays a vital role in medical and industrial imaging fields. However, the optimal balance between X‐ray absorption, decay lifetime and excitonic utilization efficiency of scintillators to achieve high‐resolution imaging is extremely difficult due to the inherent contradiction. Here two thermally activated delayed fluorescence (TADF)‐actived coinage‐metal clusters M6S6L6 (M=Ag or Cu) were synthesized by simple solvothermal reaction, where the cooperation of heavy atom‐rich character and TADF mechanism supports strong X‐ray absorption and rapid luminescent collection of excitons. Excitingly, Ag6S6L6 (SC‐Ag) displays a high photoluminescence quantum yield of 91.6 % and scintillating light yield of 17420 photons MeV−1, as well as a low detection limit of 208.65 nGy s−1 that is 26 times lower than the medical standard (5.5 μGy s−1). More importantly, a high X‐ray imaging resolution of 16 lp/mm based on SC‐Ag screen is demonstrated. Besides, rigid core skeleton reinforced by metallophilicity endows clusters M6S6L6 strong resistance to humidity and radiation. This work provides a new view for the design of efficient scintillators and opens the research door for silver clusters in scintillation application. [ABSTRACT FROM AUTHOR]

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]

By the coordination assembly of a redox photoactive functional motif and a cyanide-bridged moiety, a cyanide-bridged MnII–FeIII compound with large photoinduced magnetic change at room-temperature due to photoinduced electron transfer was obtanied. This compound also shows unprecedented radical-quenched spin glass in molecule based magnets. [ABSTRACT FROM AUTHOR]