Latest ArticlesCrystal habit and crystal form are critical elements in determining product properties and functions. In this work, we developed a microfluidic antisolvent crystallization technique to rapidly screen and accurately control the solid form and crystal habit of triphenylmethanol (Ph3COH). This advanced technique separates the primary mixing of solutions from crystal formation (nucleation and growth) by introducing the microfluidic device, avoiding clogging in microchannels to obtain high-quality crystals. The results show that we can achieve controllable preparation of pure 2Ph3COH·DMSO (DMSO solvate), pure Ph3COH (form β), and mixed crystals with different mass ratios. Moreover, the microscale can prompt the DMSO solvate to grow into hexagonal sheet-like and bulk crystals. We can regulate the aspect ratio of hexagonal sheet-like crystals in binary solvents and control the crystal habit of the form β to transition between long needle-like shapes and short hexagonal prisms in DMF-H2O. Meanwhile, we revealed that the solvent ratio, the antisolvent flow rate, and the initial concentration of Ph3COH are the main factors affecting the solid form selectivity and morphology transition. Such a novel method would be considered as a promising technique to be extended to screen and control key crystallization parameters of other substances.
Converting CO2 into value-added chemicals and fuels through various catalytic methods to lower the atmospheric CO2 concentration has been developed to be a crucial means to alleviate the energy shortage and ameliorate the ever-fragile environment status. However, the complexity of the CO2 conversion reaction and the strong reduction conditions lead to the inevitable structural evolution, making it difficult for the prior design of suitable catalytic materials. Herein, to guide the rational design of efficient catalysts, we will be centered on the thermal, electro, and photo-induced structural evolution and active species identification during the CO2 conversion, including the in situ/operando characterization techniques monitoring the activation, steady, and deactivation stage of the catalysts as well as the inherent restructuring mechanism towards active species. Besides, the future challenges and opportunities on the merits of combining the structural evolution with the adsorbed intermediates recognized by ultra-fast spectroscopic techniques, simultaneously, the combination of theoretical simulation and the results of in situ experiments will also be addressed. This review can not only guide the identification of real active species, but also provide an approach to design the specific active species towards CO2 conversion, rather than only focusing on activity, for the purpose of practical industrial application.
Numerous supramolecular macrocycles have been utilized for developing catalysts by exploiting their specific molecular recognition and ability to form inclusion complexes through noncovalent interactions. The cyclic structure and modified functional groups of these macrocycles can influence substrate and transition state stability, as well as reaction selectivity. The inner cavities of these macrocycles are particularly beneficial, as they enable substrates to adopt preorganized arrangements and serve as versatile platforms for highly efficient supramolecular catalytic systems. This minireview provides an overview of recent advancements in supramolecular catalysis using various macrocycles, such as crown ethers, cyclodextrins, calixarenes, pillararenes, cucurbiturils, and other novel macrocycles.
While heteroatom doping serves as a powerful strategy for devising novel polycyclic aromatic hydrocarbons (PAHs), the further fine-tuning of optoelectronic properties via the precisely altering of doping patterns remains a challenge. Herein, by changing the doping positions of heteroatoms in a diindenopyrene skeleton, we report two isomeric boron, sulfur-embedded PAHs, named Anti-B2S2 and Syn-B2S2, as electron transporting semiconductors. Detailed structure-property relationship studies revealed that the varied heteroatom positions not only change their physicochemical properties, but also largely affect their solid-state packing modes and Lewis base-triggered photophysical responses. With their low-lying frontier molecular orbital levels, n-type characteristics with electron mobilities up to 1.5 × 10−3 cm2 V−1 s−1 were achieved in solution-processed organic field-effect transistors. Our work revealed the critical role of controlling heteroatom doping patterns for designing advanced PAHs.
Hydrogen has emerged as a promising environmentally friendly energy source. The development of low-cost, highly active, stable, and easily synthesized catalysts for hydrogen evolution reactions (HER) remains a significant challenge. This study explored the synthesis of nitrogen-doped MXene-based composite catalysts for enhanced HER performance. By thermally decomposing RuCl3 coordinated with melamine and formaldehyde resin, we successfully introduced nitrogen-doped carbon (NC) with highly dispersed ruthenium (Ru) onto the MXene surface. The calcination temperature played a crucial role in controlling the size of Ru nanoparticles (Ru NPs) and the proportion of Ru single-atom (Ru SA), thereby facilitating the synergistic enhancement of HER performance by Ru NPs and Ru SA. The resulting catalyst prepared with a calcination temperature of 600 ℃, Ti3C2Tx-N/C-Ru-600 (TNCR-600), exhibited exceptional HER activity (η10 = 17 mV) and stability (160 h) under alkaline conditions. This work presented a simple and effective strategy for synthesizing composite catalysts, offering new insights into the design and regulation of high-performance Ru-based catalysts for hydrogen production.
A novel D–π–A structure and near–infrared fluorescent probe (DCITT) with high polarity sensitivity and membrane targeting was reported. The fluorescent spectra of DCITT were polarity dependent and Stokes shift was greater than 300 nm. Due to its high fluorescence quantum yield, low cytotoxicity and photostability, DCITT could be used as a labeling probe in multicellular organisms. In particular, DCITT effectively distinguished tumor cells from normal cells because it could specifically light up the cancer cells membrane based on strong red fluorescence for a long time. On this basis, a polar–sensitive cell membrane probe is developed to differentiate tumor cells from normal cells, which provides an idea and method for the early diagnosis of tumor at cellular level.
Changes in trace substances in human metabolites, which are related to disease processes and health status, can serve as chemical markers for disease diagnosis and symptom monitoring. Real-time online detection is an inevitable trend for the future of health monitoring, and the construction of chips for detection faces major challenges. The response of sensors often fails to meet the requirements for chip-based detection of trace substances due to the low efficiency of interfacial heterogeneous reactions, necessitating a rational design approach for micro- and nano-structures to improve sensor performance with respect to sensitivity and detection limits. This review focuses on the influence of micro- and nano-structures that used in chip on sensing. Firstly, this review categorizes sensors into chemiresistors, electrochemical sensors, fluorescence sensors, and surface enhanced Raman scattering (SERS) sensors based on their sensing principle, which have significant applications in disease diagnosis. Subsequently, commencing from the application requirements in the field of sensing, this review focuses on the different structures of nanoparticle (NP) assemblies, including wire, layered, core-shell, hollow, concave and deformable structures. These structures change in the size, shape, and morphology of conventional structures to achieve characteristics such as ordered alignment, high specific surface area, space limitation, vertical diffusion, and swaying behavior with fluid, thereby addressing issues such as poor signal transmission efficiency, inadequate adsorption and capture capacity, and slow mass transfer speed during sensing. Finally, the design direction of micro- and nano-structures, and possible obstacles and solutions to promote chip-based detection have been discussed. It is hope that this article will inspire the exploration of interface micro- and nano-structures modulated sensing methods.
2-Hydroxycarbazole and 4-hydroxycarbazole are important chemicals with extensive applications in optoelectronic materials and pharmaceutical field. State of the art yield of 2-hydroxycarbazole is ~30% and the reaction time is typically in hours or days. Herein, we developed a green route for the continuous and high-throughput synthesis of 2-hydroxycarbazole and 4-hydroxycarbazole via photochemical intramolecular cyclization of 3‑hydroxy-2′‑chloro-diphenylamine using a self-designed millimeter scale photoreactor, which was designed based on sizing-up and numbering-up strategies for a decent liquid holdup (6.8 mL) and fabricated via femtosecond laser engraving technique. The photochemical synthesis was carried out continuously under the illumination of 365 nm UV-LED with dimethyl sulfoxide as solvent and potassium t-butoxide as catalyst. It was found that under optimized conditions a 2-hydroxycarbazole yield of 31.6% and a 4-hydroxycarbazole yield of 11.1% were obtained with a residence time of 1 min. Compared to semi-batch operations, the reaction time was shortened by 1–2 orders of magnitude. As a result, a throughput of 11.3 g/day 2-hydroxycarbazole and 4.0 g/day 4-hydroxycarbazole can be achieved from the photoreactor. It was proposed that the short reaction time and high product yield are resulted from higher photon transfer rates and more uniform photon distribution provided by the millimeter scale photoreactor, which enhances the reaction rates and mitigates overreaction.
Single-emitter white organic light-emitting diode (WOLED) based on small organic molecule exhibits great potential in simplifying fabrication process of WOLEDs. However, the design and synthesis of molecule for highly efficient single-emitter WOLED still remains a challenge. Herein, two asymmetric donor-acceptor-acceptor' (D-A-A') type molecule (PTZ-PQ-F and PTZ-PQ-CF3) are developed by employing trifluoromethyl (CF3) or fluorine atom as secondary acceptor, which can exhibit white lighting with dual emission bands consisting of blue traditional fluorescence from quasi-axial (ax) conformer and orange thermally activated delayed fluorescence (TADF) from quasi-equatorial (eq) conformer. The introduction of CF3 into PTZ-PQ-CF3 greatly enhanced the photoluminescence quantum yield (PLQY) by suppressing the nonradiative deactivation. Owing to electron-inductive-effect of CF3, the "eq" conformer of PTZ-PQ-CF3 exhibits a much smaller ΔEST of 0.01 eV to realize more efficient reverse intersystem crossing (RISC) process, and then enhance the exciton utilization (nearly 100%) of the whole dual emission system. Consequently, single-emitter WOLEDs based on PTZ-PQ-CF3 show nearly standard white emission with EQE of 13.0% and CIE of (0.35, 0.36) in mCP host and show warm white emission with high EQE of 25.5% and CIE of (0.40, 0.47) in 35 DczPPy host, which are the best performance among reported single-emitter WOLEDs.
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