Precision Chemistry最新文献

[This corrects the article DOI: 10.1021/prechem.4c00064.].

Twisted nanographenes (NGs) are currently attracting a lot of attention owing to their geometrical and electronic structures that differ substantively from conventional planar and nonplanar NGs, while the strategic synthesis of twisted NGs is still a topic of interest because the products are often interconvertible among unidirectionally, alternatively, or randomly twisted geometries and otherwise obtained as a mixture of them. Herein, we report the conformationally specific synthesis of twisted NGs where the geometry was reinforced by introducing 1,4-dioxane rings at a K-region of a central pyrene core that bears a large contortion. The 1,4-dioxane rings were generated by semi-deprotection, of tetraoxa[4.4.4]-propellanes in precursor molecules, which were confirmed to be engaged in forming C-C bonds via a Friedel-Crafts type mechanism. The large contortion within the pyrene core causes a narrowed HOMO-LUMO gap on account of unusual p _z -lobe overlap between +z and -z sides, giving rise to red emission with a high quantum yield of 94% as well as stable redox processes of 2e^- uptake/release.

Hydrogen transfer is a fundamental chemical process critical to the design and application of organic molecules and functional devices. By uncovering the dynamic interactions between atoms within molecules, hydrogen transfer research offers innovative pathways for creating advanced functional materials and devices. These advancements have driven progress in areas such as optoelectronics, molecular switches, and bioimaging. This review explores the various forms of hydrogen transfer, including hydrogen atom, proton, and hydride transfer, highlighting their mechanisms and key reactions. It also examines the integration of these processes into molecular devices, including single-molecule systems, molecular films, and organic frameworks. Future directions emphasize precise control of hydrogen transfer pathways, development of highly selective and efficient reaction systems, and the design of robust devices based on these processes. These efforts aim to enhance device performance and broaden applications in intelligent materials, integrated functions, and information technology.

Photoresponsive coatings that can change their color in response to light at ambient temperature have large potential applications. Cholesteric liquid crystals (CLCs) are promising photochromic materials, as they are known to reflect light selectively and their optical properties can be modulated with a wide range. However, it remains a major challenge to fabricate photoresponsive coatings that combine fast and good responsivity, fabrication feasibility, and mechanical strength and, more importantly, that can be applied at a large area with excellent stability. In this study, Pickering emulsions containing CLC microdroplets doped with light-driven molecular motors as photoresponsive chiral dopants were prepared via cellulose nanocrystals (CNCs) which serve as both Pickering emulsifiers and alignment agents of CLCs. A melamine-formaldehyde (MF) resin hybrid shell was fabricated via in situ polymerization to form thermally stable CLC microcapsules. These microcapsules were mixed with curable binders, resulting in photoresponsive coatings. The photochromic material which features highly selective addressability of the reflective light wavelength in the visible light region, good reversibility, and viewing angle independence was painted in a large area on both hard and soft substrates, providing a versatile platform for enhanced encryption and smart coatings.

Nonenzymatic nucleic acid amplification reactions, especially nonenzymatic DNA amplification reactions (NDARs), are thermodynamically driven processes that operate without enzymes, relying on toehold-mediated strand displacement (TMSD) and branch migration. With their sensitive and efficient signal amplification capabilities, NDARs have become essential tools for biomarker detection and intracellular imaging. They encompass four primary amplification methods: catalytic hairpin assembly (CHA), hybridization chain reaction (HCR), DNAzyme-based amplification, and entropy-driven circuits (EDC). Based on amplification mechanisms, NDARs can be categorized into three types: stimuli-responsive NDARs, which employ single amplification strategies triggered by specific stimuli like pH, light, or biomolecules; cascade NDARs, which integrate two or more amplification reactions for stepwise signal enhancement; and autocatalytic NDARs, which achieve exponential amplification through self-sustained cycling. These advanced designs progressively improve amplification efficiency, enhance sensitivity, and minimize background noise, enabling precise detection of proteins, viruses, and nucleic acids as well as applications in cancer cell imaging and therapy. Compared with classical NDARs, these approaches significantly reduce signal leakage, offering broader applicability in diagnostics, imaging, and therapeutic contexts. This review summarizes recent advancements, addresses existing challenges, and explores future directions, providing insights into the development and applications of NDARs.

A miniaturized, biomarker-based diagnostic for preterm birth (PTB) risk will require multiple sample preparation steps to be integrated in a single platform. To this end, we created a 3D printed microfluidic device that combines immunoaffinity extraction (IAE), solid-phase extraction (SPE), and fluorescent labeling. This device uses an antibody-functionalized IAE monolith to selectively extract PTB biomarkers, a lauryl methacrylate reverse-phase SPE monolith to concentrate and facilitate fluorescent labeling of PTB biomarkers, and 3D printed valves to control flow through the monoliths. The advantageous iterative design process for arriving at a functional device is documented. The IAE/SPE device performed selective, reproducible extractions of three PTB biomarkers from buffer and depleted maternal blood serum, demonstrating its utility for single-biomarker and multiplexed extractions. After tandem extraction and fluorescent labeling, biomarkers eluted from the SPE monolith in a concentrated plug, facilitating future integration with downstream analysis techniques including microchip electrophoresis. This device effectively combines and automates orthogonal chromatographic extraction methods and constitutes a substantial step toward a complete microfluidic PTB prediction platform.

Controlling the electronic states of Pt-based catalysts holds great promise for enhancing the intrinsic activity of the oxygen reduction reaction (ORR). Herein, inspired by first-principles simulations, we propose a strategy using metal host-guest interactions to tune Pt 5d electronic characteristics to optimize the adsorption strength of the key *OH intermediate. The hybrid electrocatalyst of Pt nanoparticles on a single-atom Co-N-C support (Pt@Co_L SAs) exhibits a half-wave potential of 0.92 V and a mass activity of 3.2 A·mg_Pt ^-1 at 0.9 V in 0.1 M HClO₄, which is a 20-fold enhancement compared with commercial Pt/C. Impressively, the Pt loading in the catalyst is as low as 1.70 wt %, which represents the lowest value reported in the relevant literature on Pt-based acidic ORR catalysts. Comprehensive spectroscopy investigations and theoretical simulations revealed that the precise regulatory effect of Co in various dispersion states effectively weakens the intermediate adsorption and reduces the energy barrier for the water decomposition step. Our finding provides valuable insights for the development of advanced ultralow-Pt ORR catalysts via the integration engineering of multiple metal sites.