Latest ArticlesThe enantioselective separation of racemate, particularly those containing C(sp3)-H bonds knowns for their high bond dissociation energies and significant polarity, presents a significant challenge in pharmaceutical synthesis. Recent advances have witnessed the fusion of photocatalysis with hydrogen atom transfer (HAT) methodologies, marking a notable trend in synthesis of chiral molecules. This technique uses the excitation of a catalyst to activate substrates, enabling the selective isomerization of chiral centers containing C(sp3) configurations. This process distinctively facilitates the direct activation of the C(sp3)-H bond in targeted reagents. This review systematically discusses the photocatalytic isomerization of various chiral molecule featuring C(sp3)-H centers, capable of undergoing deracemization through two primary HAT mechanisms: direct and indirect pathways. From the perspective of synthetic organic chemistry, this field has progressed towards the development of isomerization strategies for molecules that incorporate an activating group at the α-position adjacent to the C(sp3) chiral center. Moreover, it covers methodologies applicable to molecules characterized by specific C-C and C-S bond configurations. The integration of photocatalysis with HAT technology thus provides valuable strategies for the synthesis of enantiopure compounds with enhanced selectivity and efficiency.
Utilizing transporter-mediated drug delivery to achieve effective oral absorption emerges as a promising strategy. Researchers have been concentrated on discovering solutions to the issues of low solubility and poor permeability of insoluble drugs, whereas, current reports have revealed that drug transporter proteins are abundantly expressed in the mucosa of intestinal epithelial cells, and that their mediated drug absorption effectively improved the bioavailability of orally administered drugs. There are two main categories based on the transporter mechanism, which include the family of ATP-binding cassette (ABC) transporters with efflux effects that reduce drug bioavailability and the family of solute carriers (SLC) transporters with uptake effects that promote drug absorption, respectively. Thus, we review studies of intestinal transporter-mediated delivery of drugs to enhance oral absorption, including the types of intestinal transporters, distribution characteristics, and strategies for enhancing oral absorption using transporter-mediated drug delivery systems are summarized, with the aim of providing important theoretical references for the development of intestinal-targeted delivery system.
Nanochannel technology based on ionic current rectification has emerged as a powerful tool for the detection of biomolecules owing to unique advantages. Nevertheless, existing nanochannel sensors mainly focus on the detection of targets in solution or inside the cells, moreover, they only have a single function, greatly limiting their application. Herein, we fabricated SuperDNA self-assembled conical nanochannel, which was clamped in the middle of self-made device for two functions: Online detecting living cells released TNF-α and studying intercellular communication. Polyethylene terephthalate (PET) membrane incubated tumor associated macrophages and tumor cells was rolled up and inserted into the left and right chamber of the device, respectively. Through monitoring the ion current change in the nanochannel, tumor associated macrophages released TNF-α could be in situ and noninvasive detected with a detection limit of 0.23 pg/mL. Furthermore, the secreted TNF-α induced epithelial-mesenchymal transformation of tumor cells in the right chamber was also studied. The presented strategy displayed outstanding performance and multi-function, providing a promising platform for in situ non-destructive detection of cell secretions and related intercellular communication analysis.
Carbon dots (CDs) are an emerging class of zero-dimensional carbon nano optical materials that are as promising candidates for various applications. Through the exploration of scientific researchers, the optical band gap of CDs has been continuously regulated and red-shifted from the initial blue-violet light to longer wavelengths. In recent years, CDs with near-infrared (NIR) absorption/emission have been gradually reported. Because NIR light has deeper penetration and lower scattering and is invisible to the human eye, it has great application prospects in the fields of biological imaging and treatment, information encryption, optical communications, etc. Although there are a few reviews on deep red to NIR CDs, they only focus on the single biomedical direction. There is still a lack of comprehensive reviews focusing on NIR (≥700 nm) absorption and luminescent CDs and their multifunctional applications. Based on our research group’s findings on NIR CDs, this review summarizes recent advancements in their preparation strategies and applications, points out the current shortcomings and challenges, and anticipates future development trajectories.
Polycyclic compounds are widely found in natural products and drug molecules with important biological activities, which attracted the attention of many chemists. Phosphine-catalyzed nucleophilic addition is one of the most powerful tools for the construction of various cyclic compounds with the advantages of atom economy, mild reaction conditions and simplicity of operation. Allenolates, Morita−Baylis−Hillman (MBH) alcohols and their derivatives (MBHADs), electron-deficient olefins and alkynes are very efficient substrates in phosphine mediated annulations, which formed many phosphonium species such as β-phosphonium enolates, β-phosphonium dienolates and vinyl phosphonium ylides as intermediates. This review describes the reactivities of these phosphonium zwitterions and summarizes the synthesis of polycycle compounds through phosphine-mediated intramolecular and intermolecular sequential annulations. Thus, a systematic summary of the research process based on the phosphine-mediated sequential annulations of allenolates, MBH alcohols and MBHADs, electron-deficient olefins and alkynes are presented in Chapters 2–6, respectively.
Room-temperature phosphorescence (RTP) materials exhibiting long emission lifetimes have gained increasing attention owing to their potential applications in encryption, anti-counterfeiting, and sensing. However, most polymers exhibit a short RTP lifetime (<1 s) because of their unstable triplet excitons. Herein, a new strategy of polymer chain stabilized phosphorescence (PCSP), which yields a new kind of RTP polymers with an ultralong lifetime and a sensitive oxygen response, has been reported. The rigid polymer chains of poly(methyl mathacrylate) (PMMA) immobilize the emitter molecules through multiple interactions between them, giving rise to efficient RTP. Meanwhile, the loosely-packed amorphous polymer chains allow oxygen to diffuse inside, endowing the doped polymers with oxygen sensitivity. Flexible and transparent polymer films exhibited an impressive ultralong RTP lifetime of 2.57 s at room temperature in vacuum, which was among the best performance of PMMA. Intriguingly, their RTP was rapidly quenched in the presence of oxygen. Furthermore, RTP microparticles with a diameter of 1.63 µm were synthesized using in situ dispersion polymerization technique. Finally, oxygen sensors for quick, visual, and quantitative oxygen detection were developed based on the RTP microparticles through phosphorescence lifetime and image analysis. With distinctive advantages such as an ultralong lifetime, oxygen sensitivity, ease of fabrication, and cost-effectiveness, PCSP opens a new avenue to sensitive materials for oxygen detection.
Transition metal cobalt exhibits strong activation capabilities for alkanes, however, the instability of Co sites leads to sintering and coke deposition, resulting in rapid deactivation. Hierarchical zeolites, with their diverse pore structures and high surface areas, are used to effectively anchor metals and enhance coke tolerance. Herein, a post-treatment method using an alkaline solution was employed to synthesize meso-microporous zeolite supports, which were subsequently loaded with Co species for propane dehydrogenation catalyst. The results indicate that the application of NaOH, an inorganic base, produces supports with a larger mesopore volume and more abundant hydroxyl nests compared to TPAOH, an organic base. UV–vis, Raman, and XPS analyses reveal that Co in the 0.5Co/SN-1–0.05 catalyst is mainly in the form of tetrahedral Co2+, which effectively activates CH bonds. In contrast, the 0.5Co/S-1 catalyst contains mainly Co3O4 species. Co2+ supported on hierarchical zeolites shows better propane conversion (58.6%) and propylene selectivity (>96%) compared to pure silica zeolites. Coke characterization indicates that hierarchical zeolites accumulate more coke, but it is mostly in the form of easily removable disordered carbon. The mesopores in the microporous zeolite support help disperse the active Co metal and facilitate coke removal during dehydrogenation, effectively preventing deactivation from sintering and coke coverage.
On-demand droplet manipulation plays a critical role in microfluidics, bio/chemical detection and micro-reactions. Acoustic droplet manipulation has emerged as a promising technique due to its non-contact nature, biocompatibility and precision, circumventing the complexities associated with other methods requiring surface or droplet pretreatment. Despite their promise, existing methods for acoustic droplet manipulation often involve complex hardware setups and difficulty for controlling individual droplet amidst multiple ones. Here we fabricate simple yet effective acoustic tweezers for in-surface and out-of-surface droplet manipulation. It is found that droplets can be transported on the superhydrophobic surfaces when the acoustic radiation force surpasses the friction force. Using a two-axis acoustic tweezer, droplets can be maneuvered along arbitrarily programmed paths on the surfaces. By introducing multiple labyrinthine structures on the superhydrophobic surface, individual droplet manipulation is realized by constraining the unselected droplets in the labyrinthine structures. In addition, a three-axis acoustic tweezer is developed for manipulating droplets in three-dimensional space. Potential applications of the acoustic tweezers for micro-reaction, bio-assay and chemical analysis are also demonstrated.
Generally, gaining fundamental insights into chain processes during the combustion of flame-retardant polymers relies on the qualitative and quantitative characterization of key chain carriers. However, polymer combustion processes based on conventional solid-fuel combustion strategies, due to the high coupling of pyrolysis, combustion, soot formation and oxidation, exhibit relatively high complexity and poor flame stability, and lead to a huge obstacle to the use of optical diagnostics. Herein, a spatial-confinement combustion strategy, which can produce a special staged flame with multi-jets secondary wave, is devised to provide a highly decoupled combustion environment. Glowing soot particles are therefore decoupled from main chemiluminescence region and confined to the flame tip to provide a well-controlled, optical-thin test environment for combustion diagnostic. Based on this strategy, a multi-nozzle-separation (MNS) burner is designed and fabricated, and the combustion processes associated with four model compounds, PVC, PS, PP/TBBA blends and PP/RP blends are investigated by spontaneous spectral diagnosis, and the chemiluminescence fingerprint of key diatomic/triatomic intermediates (such as OH, CH, C2, ClO, Br2, and PHO) are clearly observed. This encouraging result means that the strategy of spatial-confinement combustion we proposed shows promising prospect in many subjects associated with combustion chain regulation, such as efficient design of flame retardants.
Heterocyclic compounds play an important role in organic hole transport materials (HTMs) for perovskite solar cells (PSCs). Herein, a series of linear D-π-D HTMs (OCBz, S-CBz, SO2-CBz) with different dibenzo-heterocycles core (dibenzofuran, dibenzothiophene, dibenzothiophene sulfone) were designed and synthesized, and their applications in PSCs were investigated. The intrinsic properties (CV, UV–vis, hole mobility and conductivity) were systematically investigated, demonstrating that all three materials are suitable HTMs for planar n-i-p type PSCs. Benefiting from the excellent hole mobility and conductivity, good film forming ability, and outstanding charge extraction and transport capability of S-CBz, FAPbI3-based PSCs using S-CBz as HTM achieved a PCE of 25.0%, which is superior to that of Spiro-OMeTAD-based PSCs fabricated under the same conditions (23.9%). Furthermore, due to the interaction between S and Pb2+, S-CBz-based PSC devices exhibited improved stability. This work demonstrates that dibenzothiophene-based architectures are promising candidates for high-performance HTMs in perovskite solar cell architectures.
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