Latest ArticlesFerroelectric semiconductors have sparked growing attention in the field of optoelectronics, due to their unique ferroelectric photovoltaic effect. Recently, substantial efforts have been devoted to the development of ferroelectric semiconductors, including inorganic oxides, organic-inorganic hybrids, and metal-free perovskites. Nevertheless, reports of ferroelectric semiconductors with a bandgap of less than 2 eV have been scarce. Here, in combination with the incorporation of triiodide (I3−) and the introduction of chiral cations, we successfully constructed a pair of enantiomeric organic-inorganic hybrid ferroelectric semiconductors, (S-1,2-DAP·I)4·I3·BiI6 and (R-1,2-DAP·I)4·I3·BiI6 (R/S-1,2-DAP = (R/S)-(–)-1,2-diaminopropane), which possess high-temperature multiaxial ferroelectric phase transition with an Aizu notation of 422F2(s) at 405 K, a narrow bandgap of 1.56 eV comparable to that of CH3NH3PbI3 (~1.5 eV), and an impressive piezoelectric response (piezoelectric coefficient, d22 of 35 pC/N) on par with PVDF (polyvinylidene fluoride, 30 pC/N). With intriguing attributes, (S-1,2-DAP·I)4·I3·BiI6 and (R-1,2-DAP·I)4·I3·BiI6 exhibit great potential for application of self-power polarized-light detection and piezoelectric sensors.
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
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.
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.
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.
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.
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.
Dentin hypersensitivity (DH) associated with dentinal tubule exposure is one of the most common causes of toothache with a rapid onset and short duration. Medication, filling repair, laser irradiation, crown therapy, and desensitizing toothpaste are standard clinical treatment strategies, but unsatisfactory treatment modalities are marked by long-term administration, poor dentinal tubule closure, microleakage, and the development of secondary caries. To improve the treatment efficiency of DH, numerous organic or inorganic biomaterials have been developed to relieve toothache and reverse the instability of desensitization. Biomaterials are expected to participate in dental remineralization to achieve desensitization. This review discusses various biomaterials for DH therapy based on different desensitization mechanisms, including dentinal tubule closure and dental nerve blockade, and presents a perspective on the underlying future of dentin regeneration medicine for DH therapy.
Silicon is recognized as the most advantageous next-generation anode material for LIBs in terms of its extremely high theoretical capacity and appropriate operating voltage. However, the application of Si anode is limited by huge volume expansion emerging with cycling, which in turn induces the collapse of the electrode structure, resulting in rapid capacity decay. Here, we report a strategy using self-swelling artificial laponite to prepare a laponite/MXene/CNT composite framework with both rigidity and flexibility, which can excellently address these challenges of Si anode. The self-swelling artificial laponite participates in the construction of hierarchical and porous structures, providing sufficient buffer space to mitigate the volume expansion of the LixSi alloying reaction. Meanwhile, tough and tightly cross-linked silicate nanosheets can improve the mechanical strength of the framework for strong structural stability. More importantly, the negative charge between the layers of artificial laponite can effectively promote fast Li-ion transport in the electrode. This free-standing silicon anode enables the preparation of high areal capacity electrodes to further enhance the energy density of LIBs and a higher reversible capacity of 2381.8 mAh/g at 0.1 C after 50 cycles with an initial coulombic of 85.6%. This work provides a simple and practical fabrication strategy for developing high-performance Si-based batteries, which can speed up their commercialization.
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