Latest ArticlesDeveloping efficient and long wavelength sensitive unimolecular photoinitiators (PIs) is still facing a great challenge. In this work, a series of thioxanthone-based N-hydroxyphthalimide esters (TX-NHPIEs) were synthesized by installing NHPIEs along the TX backbone and characterized. The investigated TX-NHPIEs have a 60 nm redshift and demonstrate sterling initiating efficiency for free radical photopolymerization (FRP) under LED@450 nm light irradiation compared with the commercialized isopropylthioxanthone (ITX). Real-time 1Hnuclear magnetic resonance (1H NMR), electron spin resonance (ESR), decarboxylation and gas chromatograph-mass spectrometer (GC–MS) experiments and density functional theory (DFT) reveal that TX-NHPIEs can generate one alkyl radical and one N-centered iminyl radical, which can initiate FRP directly and indirectly, respectively. In other words, TX-NHPIEs absorb one photon and can generate two active radicals, which break through the limitations of common PIs. TX-NHPIE-Cpe demonstrates the highest initiating efficiency, and its application in coatings and 3D printing was also studied, indicating TX-NHPIEs have broad potential applications in photopolymerization processes.
Formic acid (FA), which is obtainable through CO2 hydrogenation with green hydrogen or biomass conversion, has been used as a prospective liquid organic hydrogen carrier (LOHC) because of the abundant advantages of renewability, wide availability, stability, and high volumetric capacity (53 g H2/L). The development of highly efficient catalytic systems to achieve enhanced catalytic activity is attractive but still challenging. Herein, ultrafine and highly dispersed PdAu nanoclusters (NCs) anchored on amino-modified reduced graphene oxide (ArGO) were successfully synthesized via a facile impregnation-reduction method and applied as a catalyst toward formic acid dehydrogenation (FAD). Benefiting from the promoting effect of amino groups, the strain and ligand effect in the alloy, and the Mott–Schottky effect between PdAu NCs and ArGO, the resultant PdAu/ArGO affords an ultrahigh activity under visible light irradiation with an exceptional turnover frequency value of 10, 699.5 h−1 at 298 K without any additives, more than 2.6 times improvement than that under dark, which is the highest among all reported catalysts under the same conditions. This study provides a green and convenient strategy for developing more efficient and sustainable FAD catalysts and promotes the effective utilization of FA as a prospective renewable LOHC.
A copper(Ⅰ)-catalyzed diastereodivergent addition of phosphinothioates (HP(S)ROR') to α, β-unsaturated thioamides is disclosed, which constructs vicinal P-chiral and C-chiral centers in generally high diastereo- and enantioselectivities. In this reaction, the kinetic resolution of HP(S)ROR' occurs, which affords (R)-HP(S)PhOMe in high enantioselectivity in the addition with (R, R)-Ph-BPE as the ligand. It is found through control experiment that dual "soft-soft" interaction, indicated by both 1H and 31P NMR experiments, is indispensable in the present reaction. The first "soft-soft" interaction between copper(Ⅰ) catalyst and HP(S)ROR' enables facile deprotonation to generate nucleophilic [Cu]-SPROR' species. The second one between the [Cu]-SPROR' species and α, β-unsaturated thioamides facilitated the nucleophilic addition. Finally, both Michael adducts and (R)-HP(S)PhOMe are easily converted to synthetically useful compounds.
Lithium-sulfur batteries (LSBs) boasting remarkable energy density have garnered significant attention within academic and industrial spheres. Nevertheless, the progression of LSBs remains constrained by the languid redox kinetics intrinsic to sulfur and the pronounced shuttle effect induced by lithium polysulfides (LiPSs), which seriously affecting the energy density, cycling life and rate capacity. The conceptualization and implementation of catalytic materials stand acknowledged as a propitious stratagem for orchestrating kinetic modulation, particularly in excavating the conversion of LiPSs and has evolved into a focal point for disposing. Among them, chalcogenide catalytic materials (CCMs) have shown satisfactory catalytic effects ascribe to the unique physicochemical properties, and have been extensively developed in recent years. Considering the lack of systematic summary regarding the development of CCMs and corresponding performance optimization strategies, herein, we initiate a comprehensive review regarding the recent progress of CCMs for effective collaborative immobilization and accelerated transformation kinetics of LiPSs. Following that, the modulation strategies to improve the catalytic activity of CCMs are summarized, including structural engineering (morphology engineering, surface/interface engineering, crystal engineering) and electronic engineering (doping and vacancy, etc.). Finally, the application prospect of CCMs in LSBs is clarified, and some enlightenment is provided for the reasonable design of CCMs serving practical LSBs.
The conjugate addition of in-situ generated (aza-)quinone methides (QMs) and indole imine methides (IIMs) emerged as a powerful protocol to access densely functionalized benzenes and indoles. Hydroxybenzyl alcohols, aminobenzhydryl alcohols, and varied indolylmethanols served as most effective precursors for the in-situ generation of such reactive species under acid conditions. The relevant propargylic alcohol has proven to be an elegant precursor to generate the propargylic-QMs and -IIMs via the acid promoted dehydration process, thus enabling diverse challenging remote activation to proceed conjugate 1,6- and 1,8-additions. Moreover, the heteroarene has proven to be workable to transfer the LUMO of the p-QMs and 2-IIMs, thus inducing the remote nucleophilic dearomative additions. The conjugate additions of (aza-)p-QMs and varied IIMs has made significant contribution in the field of remote activation chemistry in past decade. This review summarizes the latest advances of the remote conjugate additions of the in-situ generated QMs and IIMs.
Indole is a biologically active compound formed by the fusion of benzene and pyrrole, and it is widely found in natural products and drugs. Due to the unique structure and properties of indole, its derivatives often exhibit distinctive physiological activities, which has led to widespread attention in the field of pesticide development. Analyzing the design strategies and structure-activity relationships (SARs) of compounds is a crucial step in developing novel pesticides. This review mainly summarizes indole compounds with plant growth regulating, antiviral, fungicidal, herbicidal, and insecticidal activities, with the aim of providing new insights into the discovery and mechanism of action of novel indole-based pesticides.
Insufficient intratumoral retention of nanomedicines remains the major challenge for broad implementation in clinical sets. Herein, we proposed a legumain-triggered aggregable gold nanoparticle (GNP) delivery platform (GNPs-A&C). GNPs-A&C could form intratumoral or intracellular aggregates in response to the overexpressed legumain. The aggregates with size increase not only could reduce back-flow from interstitial space to peripheral bloodstream but also could restrict the cellular exocytosis, leading to enhanced intratumoral retention. In vitro studies demonstrated that GNPs-A&C possessed an excellent legumain responsiveness and the increased size was closely relevant with legumain expression. In vivo studies demonstrated GNPs-A&C possessed slower clearance rate and much higher intratumoral retention within legumain-overexpressed tumor compared to non-aggregable NPs, regardless of intravenous or intratumoral injection. More importantly, this delivery platform significantly improved the chemotherapeutic effect of doxorubicin (DOX) towards subcutaneous xenograft C6 tumor. The effectiveness of this stimulus-responsive aggregable delivery system provides a thinking for designing more intelligent size-tunable nanomedicine that can substantially improve intratumoral retention.
The preparation of Pd-based catalysts with rich electrons and a high atom dispersion rate is of great significance for improving the reactivity of cross-coupling reactions, which is a powerful tool for pharmaceutical and fine chemical synthesis. Here, we report a PdNi single-atom alloy (SAA) catalyst in which isolated Pd single atoms are anchored onto the surface of Ni nanoparticles (NPs) applied for Suzuki coupling reactions and Heck coupling reactions. The 0.1% PdNi SAA exhibits extraordinary catalytic activity (reaction rate: 17,032.25 mmol h−1 gPd−1) toward the Suzuki cross-coupling reaction between 4-bromoanisole and phenylboronic acid at 80℃ for 1 h. The excellent activity is supposed to attribute to the 100 percent utilization rate of Pd atoms and the highly stable surface zero-valance Pd atoms, which provides abundant sites and electrons for the adsorption and fracture of the C-X (X = Cl, Br, I) bond. Moreover, our work demonstrates the excellent application prospect of SAAs for cross-coupling reactions.
Anticancer platinum prodrugs that can be controllably activated are highly desired for personalized precision medicine and patient compliance in cancer therapy. However, the clinical application of platinum(Ⅳ) prodrugs (Pt(Ⅳ)) is restricted by tissue penetration of external irradiation. Here, we report a novel Pt(Ⅳ) activation strategy based on endogenous luminescence of tumor microenvironment responsiveness, which completely circumvents the limitation of external irradiation. The designed Pt(Ⅳ)Lu, a mixture of trans, trans, trans-[Pt(N3)2(OH)2(py)2] and luminol (Lu), has controllable activation property: it remains inert in reductant environment and normal tissues, but under tumor microenvironment, Lu will be oxidized to produce blue luminescence, which rapidly reduce Pt(Ⅳ) to Pt(Ⅱ) without the need of any external activator. Pt(Ⅳ)Lu shows excellent responsive antitumor ability both in vitro and in vivo. Compared to cisplatin, the median lethal dose in BALB/c mice increased by an order of magnitude. Our results suggest that Pt(Ⅳ)Lu exhibits highly controllable activation property, superior antitumor activity, and good biosafety, which may provide a novel strategy for the design of platinum prodrugs.
To overcome the conflict between the long-wavelength excitation and high singlet oxygen quantum yield of photosensitizers, we conjugated a two-photon fluorophore, tetrahydroquinoxaline coumarin (TQ), and an efficient photodynamic therapeutic agent, benzo[a]phenothiazinium (NBS-NH2), through a hexamethylene linker to build a two-photon photosensitizer, TQ-NBS. In TQ-NBS, TQ served as an energy donor and NBS-NH2 acted as an energy acceptor; and TQ-NBS was a Förster resonance energy transfer (FRET) cassette with a 92.8% efficiency. The large two-photon absorption cross-section of TQ allowed photosensitizer TQ-NBS to work in a 900 nm two-photon excitation (TPE) mode, which greatly benefited the deep tissue penetration in PDT treatment. Meanwhile, the excellent phototoxicity and near-infrared fluorescence of NBS-NH2 was kept in TQ-NBS under a TPE mode via a FRET process. Photosensitizer TQ-NBS exhibited a high phototoxic efficacy in living cells and tumor-bearing mice.
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