Latest ArticlesAdsorptive separation of acetylene (C2H2) from carbon dioxide (CO2) is of great significance in petrochemical industry, but still remains as a daunting challenge by reason of their very similar molecular sizes/shapes and physical properties. Herein, we reported a new perchlorate-based hybrid ultramicroporous material ZJU-194 that features the unique flexible-robust network decorated with rich bare oxygen atoms. By integrating the refined pore space as well as specific binding sites, the activated ZJU-194 (ZJU-194a) enables a selective two-step gate-opening adsorption toward C2H2, but blocks off the further uptake of CO2. It thus exhibits a very high C2H2/CO2 selectivity (22.4) at ambient conditions, which is superior to most reported MOF materials. Its complete separation for 50/50 C2H2/CO2 mixtures is further evidenced by the dynamic breakthrough experiments.
Recently, a novel tetraarylimidazole derivative 2-(benzo[d]thiazol-2-yl)-4-(4,5-bis(4-methoxyphenyl)-1-phenyl-1H-imidazol-2-yl)-phenol (be called MHBT herein) was architectured by our research group showing the fascinating synergy of aggregation-induced emission (AIE) characteristic, excited-state intramolecular proton transfer (ESIPT) mechanism and intramolecular charge transfer (ICT) effect. Nevertheless, a detailed and reasonable interpretation of its mechanisms both in theory is urgently needed. Consequently, to unveil the working mechanism meticulously, herein, we tactfully applied density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods to illuminate the underlying mechanisms in different solvent conditions. After optimizing the structures, the geometric parameters of hydrogen bonds (HBs), the infrared (IR) vibrational spectrum, the reduced density gradient (RDG) isosurfaces were calculated in detail, vividly explaining how the enhancement of HBs behaved as the driving force to proceed ESIPT process. Simultaneously, the frontier molecular orbitals (FMOs) combined with the potential energy curves (PECs) were conducted to interpretate the role and character of ICT and ESIPT in molecule MHBT. Further, the PECs of MHBT for dihedral angles in different organic solvents were calculated to compare the dominant torsion degree, rationalizing the AIE phenomenon from the view of the restriction of intramolecular rotation process. This work may well underpin the understanding of the interaction between different mechanisms in fluorescent dyes and thereby provide meaningful guideline for the design and construction of ideal molecules
Luminescent polymers have garnered considerable research attention for their excellent properties and wide range of applications in multi-responsive materials, bioimaging, and photoelectric devices. Thereout, various modulations of polymer structure are often the main approach to obtaining materials with different luminescent colors and functions. However, polymers with biodegradability, tunable color, and efficient emission simultaneously remain a challenge. Herein, we report a feasible strategy to achieve degradable and highly emissive polymers by exquisite combination and interplay of aggregation-induced emission (AIE) unit and environmental-friendly epoxide/CO2 copolymerization. A series of polycarbonates P-TEPxCNy (x = 0, 1, 2, 4, 30, 120; y = 0, 1) were prepared, with emission color changed from blue to yellow by controlling the proportion of two designed AIE-active monomers. Among them, Using P-TCN as emitting layer, high performance white light-emitting diode (WLED) device with an external quantum efficiency (EQE) of 26.09% and CIE coordinates of (0.32, 0.32) was achieved. In addition, the designed polymers can be used as selective sensors for nitroaromatic compounds in their nanoaggregate states.
Carbon dots (CDs) with room-temperature phosphorescence (RTP) have attracted dramatically growing interest in optical functional materials. However, the photoluminescence mechanism of CDs is still a vital and challenging topic. In this work, we prepared CD-based RTP materials via melting boric acid with various lengths of alkyl amine compounds as precursors. The spatial effect on the structure and the RTP properties of CDs were systematically investigated. With the increase in carbon chain length, the interplanar spacing of the carbon core expands and crosslink-enhanced emission weakens, resulting in a decrease in the phosphorescence intensity and lifetimes. Meanwhile, based on triplet-to-singlet resonance energy transfer, we employed intense and long-lived phosphorescence CDs as the donor and short-lived fluorescent dyes as the acceptor to achieve long-lived multicolor afterglow. By the triplet-to-singlet resonance energy transfer, the afterglow color can change from green to orange. The afterglow lifetimes are more than 0.9 s. Thanks to the outstanding afterglow properties, the composites were used for time-resolved and multiple-color advanced anticounterfeiting. This work will promote the design of multicolor and long-lived afterglow materials and expand their applications.
Precise and spatiotemporal control over the pesticide remains to be a challenge. More efficient controlled release systems (CRSs) have been developed to support the precise delivery of active ingredients. Herein, we incorporated the photoremovable protecting groups (PRPGs) into phenamacril (PHE) and obtained two photo-responsive fungicides of NV-PHE and DEACM-PHE. The 4,5-dimethoxy-o-nitrobenzyl (NV) or 7-diethylaminocoumarin (DEACM)-caged PHE could release the active molecule PHE after irradiation of UV light and blue light, respectively. Optical properties and in-vitro/vivo fungicidal activities of NV-PHE and DEACM-PHE demonstrated the feasibility for light controlled release of PHE. DEACM-PHE could release 98% PHE by illumination of blue light. The irradiated DEACM-PHE could preserve the similar bioactivity of PHE, and significantly improve the in-vitro/vivo fungicidal activities compared to the non-irradiated DEACM-PHE. The optical controlled release of PHE from DEACM-PHE enabled the precise and spatiotemporal delivery of PHE, diversifying the development of CRSs for pesticide, and providing environment-friendly agricultural applications with high pesticide efficiency.
Recently, two-dimension (2D) materials have fueled considerable interest in the field of gas sensing to cope urgent demands at specific scenarios. Unfortunately, the susceptibility to ambient humidity, and/or fragile operation stability always frustrate their further practicability. To overcome these drawbacks, we proposed one novel flexible gas sensor based on bismuth selenide (Bi2Se3) nanoplates for sensitive NO2 detection at room temperature. The as-prepared Bi2Se3 sensor exhibited favorable sensing performance, including remarkable NO2 selectivity, high response of 120% and fast response time of 81 s toward 5 ppm NO2, an ultralow detection limit of 100 ppb, and nice stability. Besides, the excellent humidity tolerance and mechanical flexibility endowed Bi2Se3 sensors with admirable reliability under harsh working conditions. The first-principles calculation further revealed the insights of extraordinary NO2 selectivity and the underlying gas-sensing mechanism.
Carbon dioxide-based polyols with ultra-low molecular weight (ULMW, Mn < 1000 g/mol) are emergent polyurethane precursors with economic and environmental benefits. However, the lack of effective proton-tolerant catalytic systems limits the development of this field. In this work, the polymeric aluminum porphyrin catalyst (PAPC) system was applied to the copolymerization of CO2 and propylene oxide, where sebacic acid, bisphenol A, poly(ethylene glycol), and water were used as chain transfer agents to achieve the controlled synthesis of CO2-polyols. The molecular weight of the resulting CO2-polyols could be facilely regulated in the range of 400–930 g/mol at low catalyst loadings, fully demonstrating its catalytic advantages of high activity, high product selectivity, and excellent proton tolerance of PAPC. Meanwhile, the catalytic efficiency of PAPC could reach up to 2.1–5.2 kg/g under organic CTA conditions, even reaching 1.9 kg/g using water as the CTA. The cPC content could be controlled within 1.0 wt% under the optimized conditions, indicating the excellent controllability of the PAPC system. ULMW CO2-polyols combines the advantages of low viscosity (~3000 mPa s at 25 ℃), low glass transition temperature (~−73 ℃), and high carbonate unit content (~40%), which is important for the development of high-performance polyurethanes.
In this study, a continuous-flow procedure containing four steps has been developed to synthesize Pigment Red 53 and modify its crystal structure. This process avoided the problems of conveying highly insoluble reaction intermediates by removing intermediate operating steps. After optimization, the overall yield of Pigment Red 53:1 reached 97.1% in the total residence time of 80 s by this diazotization-coupling-laking-crystal transition process. From batch to continuous flow, the purity of products increased from 97.1% to 98.2% and the median diameter of pigment particles decreased from 14 µm to 1.9 µm. This process achieved a similar crystal transition effect in 18 s as in batch, producing α, δ and ν crystals of Pigment Red 53:2 as expected. In conclusion, this continuous-flow procedure displays advantages in both synthesis and crystal transition, indicating another potential use for industrial application.
Co-crystal formation can improve the physicochemical properties of a compound, thus enhancing its druggability. Therefore, artificial intelligence-based co-crystal virtual screening in the early stage of drug development has attracted extensive attention from researchers. However, the complexity of developing and applying algorithms hinders it wide application. This study presents a data-driven co-crystal prediction method based on the XGBoost machine learning model of the scikit-learn package. The simplified molecular input line entry specification (SMILES) information of two compounds is simply inputted to determine whether a co-crystal can be formed. The data set includs the co-crystal records presented in the Cambridge Structural Database (CSD) and the records of no co-crystal formation from extant literature and experiments. RDKit molecular descriptors are adopted as the features of a compound in the data set. The developed model shows excellent performance in the proposed co-crystal training and validation sets with high accuracy, sensitivity, and F1 score. The prediction success rate of the model exceeds 90%. The model therefore provides a simple and feasible scheme for designing and screening co-crystal drugs efficiently and accurately.
Plastic and elastic behaviors of organic crystals have profound influence on the processability of pharmaceutical substances. Analogous to metals, the identifications of molecular slip planes in organic crystals are regarded as a strategy for harnessing plasticity. In this work, we experimentally characterized the form Ⅱ anhydrous theophylline (THPa) and its monohydrate (THPm) for their distinct plastic and elastic behaviors. Extensive DFT calculations were performed to model the effects of increasing lattice strains on molecular packing. We discovered that the energy barrier associated with the strain-induced molecular rearrangement would link to the plasticity of THPa, and possibly other simple aromatic compounds. Meanwhile, water molecules in THPm disrupt the stacking architecture from THPm and effectively undermine the general mechanism for plasticity. Hydrate formation would therefore be an alternative strategy to engineer the mechanical property of organic crystalline materials.
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