Latest ArticlesA general process for the construction of azaaryl alkanes was achieved by employing the photoredox/palladium dual catalysis under mild visible light irradiation. The palladium catalyst ligated with a diphosphamide ligand exhibited high effectiveness in facilitating the modular three-components transformation. Furthermore, the cascade transformation was not restricted to constructing tertiary carbon centers; it also encompassed the synthesis of more challenging quaternary carbon centers with sixteen representative azaarene-derived substrates as reactants. In addition, alkyl 1,4-dihydropyridines (DHP), alkyl BF3K, and alkyl carboxylic acids were identified as precursors for alkyl radicals. Mechanistic investigations revealed the involvement of two different active benzylic nucleophiles in the cascade transformation. One is azabenzylic radical, which generate the terminal product through an “inner sphere” reductive elimination process. The other is azabenzylic anions, generated through visible light induced radical anion cross-over, leading to the formation of terminal products via an “outer sphere” reaction pathway. The efficiency of current modular transformation was also demonstarted by the concise of oliceridine, a prominent USFDA drug for pain management.
In most Suzuki–Miyaura carbon-carbon cross-coupling reactions, the borabicyclo[3.3.1]nonane scaffold (9-BBN) only serves as an auxiliary facilitating the transmetalation step and thus is transformed into by-products. There are rare examples where the 9-BBN derivatives serve as the potentially diverse C8 building blocks in cross-coupling reactions. Herein, we report a cobalt-catalyzed migratory carbon-carbon cross-coupling reaction of the in situ formed 9-BBN ate complexes to afford diverse aryl- and alkyl-functionalized cyclooctenes. Preliminary mechanistic studies suggest the oxidation-induced cis-bicyclo[3.3.0]oct-1-ylborane is the key intermediate in this migratory cross-coupling reaction, which promotes the development of other diverse migratory cross-coupling of borate complexes.
Herein, we report an iron-promoted carbonylation-rearrangement of α-aminoaryl-tethered alkylidene cyclopropanes with CO2 to generate quinolinofuran derivatives. A variety of quinolinofuran derivatives are obtained in moderate to excellent yields, and two promising luminescent material molecules have been synthesized using the developed method. The Lewis acid FeCl3 was introduced into this reaction, which effectively promoted the ring opening and rearrangement of cyclopropanes. This reaction features a broad substrate scope, satisfactory functional group tolerance, facile scalability, and easy derivatization of the products.
The construction of triplet-to-singlet Förster resonance energy transfer (TS-FRET) systems has significantly contributed to the advancement of high-performance optoelectronic materials, particularly in the development of metal-free organic environmental afterglow materials. Despite these notable advancements, achieving highly efficient energy transfer between luminescent donor and acceptor molecules remains a formidable challenge. In this study, we present the utilization of cation-π interactions as an effective strategy to enhance TS-FRET efficiency, with the ultimate objective of further advancing fluorescence afterglow materials. Our results demonstrate that the cation-π interaction in 1D supramolecular nanorods (1D-SNRs) enhances the dipole-dipole coupling, a crucial parameter for regulating TS-FRET between the triplet state phosphorescent donor and singlet state fluorescent acceptor. As a result, we achieved an outstanding TS-FRET efficiency of up to 97%. Furthermore, the 1D-SNRs exhibit a long-lifetime afterglow property, which suggests their potential application as a cost-effective and secure medium for information encryption. Thus, our findings highlight the promising prospects of cation-π interactions in enhancing TS-FRET efficiency and advancing the field of organic photo-functional materials.
Two thioamino acids and four fluorinated amino acids were employed to substitute either partially or entirely the Ile2, Ser3, Ile6, and Ser7 residues of Leu10-teixobactin to prepare ten analogues and the bioactivity of them was investigated. The SAR studies revealed that Ile6 was tolerable for both thioamidation and fluoridation, while Ser7 was identified as the most tolerable site for thioamidation. Analogue 1a demonstrated comparable or slightly improved antibacterial activity, superior protease stability compared to Leu10-teixobactin, while not exhibiting obvious cytotoxicity against mammalian cells.
A strategy for copper-catalyzed and biphosphine ligand controlled boracarboxylation of 1,3-dienes and CO2 with 3,4-selectivity was developed. The CuCl coupled with DPPF (1,1′-bis(diphenylphosphino)ferrocene) was assigned to be the best catalyst, with 84% yield and exclusive 3,4-selectivity. The ligand effect on both catalytic activity and regioselectivity of boracarboxylation was disclosed, which is rarely reported in any copper catalyzed boracarboxylation. The borocupration process is revealed to be a vital step for the biphosphine participated boracarboxylation of 1,3-dienes with CO2. The minimal substrate distortion occurring in 3,4-borocupration favors the 3,4-regioselectivity of boracarboxylation. The “pocket” confinement and suitable βn (92°–106°) of bisphosphine ligands are demonstrated to be in favour of the interaction between LCu-Bpin complex (the catalytic precursor) and 1,3-diene substrate to decrease their interaction energy ∆Eint(ζ) in 3,4-borocupration, thus promoting the 3,4-boracarboxylation.
A cobalt pincer complex bearing both P and C-stereogenic centers has been designed and synthesized, allowing for the development of the first cobalt-catalyzed asymmetric hydrogenation of quinoxalines under relatively mild conditions. Valuable chiral 1,2,3,4-tetrahydroquinoxalines could be obtained with high yields and excellent enantioselectivities (35 examples, up to > 99% ee).
Although inductively coupled plasma mass spectrometry (ICP-MS) retains high sensitivity and has been intensively used for the measurement of 99Tc, it usually suffers from tedious, expensive, and time-consuming sample pretreatments due to the isobaric interferences from 99Ru and 98Mo1H. Herein, capillary electrophoresis (CE) was applied as sample introduction system for the sensitive, and interference-free determination of 99TcO4- from RuO4-, and MoO42- by ICP-MS with a simple sample treatment. Compared to the conventional methods, the hyphenated CE-ICP-MS avoids the use of expensive separation resins and reduces the consumption of mineral acid, representing a simpler, more efficient and environmentally benign approach. Moreover, the proposed method exhibits higher accuracy compared with the mathematical correction method using the natural isotope ratio of 99Ru and 101Ru, and significantly reduces sample consumption and the amount of waste, thus remarkably alleviating the radioactive exposure to operators and the pressure of radioactive waste treatment. Under the optimized conditions, the detection limits of 25 µg/L and 0.06 µg/L were obtained for RuO4- and ReO4- (Tc was replaced by Re), respectively, with relative standard deviation (RSD) lower than 5%. In addition, efficient recoveries of RuO4-, ReO4-, and 99TcO4- from simulated Hanford site groundwater were achieved. The method is expected to be a promising candidate for sensitive and accurate analysis of 99Tc from contaminated environmental samples.
The hydration state of amphiphilic block copolymers during the self-assembly transition is closely related to the structure and properties of copolymers. In this study, the temperature-induced self-assembly of copolymer poly(N,N-dimethylacrylamide)-poly(diacetone acrylamide) (PDMAA30-PDAAM60)2 in aqueous solution was monitored by near-infrared spectroscopy with water as a probe. The wavelet packet transform was employed to improve the spectral resolution. The spectral information of hydrated water surrounding the hydrophilic PDMAA and hydrophobic PDAAM blocks was then extracted, revealing the significant roles of water in morphological transition of the copolymer from spherical to worm-like micelles. Specifically, water molecules interacting with N atoms and C=O groups of the hydrophilic block gradually decrease during the morphological transition, while hydrogen-bond structures NH-CO of the hydrophobic block gradually break, bringing more water molecules into contact with the hydrophobic block. This work provides a foundation for exploring the role of water molecules during the self-assembly transition of complex block copolymers.
Researchers have shown significant interest in modulating the peroxidase-like activity of nanozymes. Among these, bimetallic nanozymes have shown superior peroxidase-like activity over monometallic counterparts, offering enhanced performance and cost-efficiency in nanozyme designs. Herein, bimetallic nanozymes comprising nickel (Ni) and osmium (Os) incorporated into hyaluronate (HA) have been developed, resulting in HA-Nin/Os nanoclusters. Subsequently, comprehensive characterizations have been conducted. Further investigation has revealed that HA-Nin/Os efficiently catalyzed 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation with hydrogen peroxide (H2O2), confirming its peroxidase-like behavior and role as a nanozyme. Impressively, HA-Ni2/Os (Ni/Os = 2:1) displays heightened substrate affinity, accelerated reaction rates, enhanced hydroxyl radical production in acidic conditions, and exhibits activity unit of 1224 U/mg, representing more than two-fold increase compared to non-Ni-supported Os nanozyme. Theoretical calculations indicate that Ni support enhances the peroxidase-like process of Os nanozyme by improving H2O2 adsorption and TMB oxidation. Crucially, the support of Ni does not significantly alter the other enzyme-like activities of Os nanozymes, thereby enabling Ni to selectively enhance their peroxidase-like activity. In terms of application, the peroxidase-like ability of HA-Ni2/Os, facilitated by HA's carboxyl groups enabling crosslinking, proves effective in a squamous carcinoma antigen immunoassay. Moreover, HA-Ni2/Os exhibit reliable stability, promising as a peroxidase substitute. This work underscores the advantages of incorporating Ni into Os, specifically enhancing peroxidase-like activity, highlighting the potential of Os bimetallic nanozymes for peroxidase-based applications.
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