Compared to electron transporting layer materials, the species and numbers of hole transporting layer (HTL) materials for organic solar cells (OSCs) are rare. The development of HTL materials with excellent hole collection ability and non-corrosive nature is a long-standing issue in the field of OSCs. Herein, we designed and synthesized a series of conjugated polyelectrolytes (CPEs) with continuously varied energy levels toward HTL materials for efficient OSCs. Through a “mutual doping” treatment, we obtained a CPE composite PCT-F:POM with a WF of 5.48 eV and a conductivity of 1.56 х 10 –3 S/m, meaning that a good hole collection ability can be expected for PCT-F:POM. The OSC modified by PCT-F:POM showed a high PCE of 18.0%, which was superior to the reference device with PEDOT:PSS. Moreover, the PCT-F:POM-based OSC could maintain 91% of the initial PCE value after storage of 20 d, meaning that the long-term stability of OSCs is improved by incorporating the PCT-F:POM HTL. In addition, PCT-F:POM possesses good compatibility with large-area processing technique; i.e., a PCT-F:POM HTL was processed by the blade-coating method for fabricating 1 cm 2 OSC, and a PCE of 15.1% could be achieved. The results suggest the promising perspective of PCT-F:POM in practical applications.
N, N, N-Trimethyl-D-glucosamine (TMG)-chitotriomycin, a naturally occurring chitin related oligosaccharide, is a specific β- N-acetylhexosaminidases (HexNAcases) inhibitor for insects and fungi. Although TMG-chitoriomycin holds great promise as a novel class insecticide and fungicide, the limited accessibility of TMG-chitotriomycin prevents its further biological evaluation. We report herein a simple and eco-friendly chemoenzymatic approach for the efficient synthesis of TMG-chitotriomycin and its analogues. In this strategy, the readily available chitosan was enzymatically hydrolyzed and chemically N-acetylated to afford the chitooligosaccharides ranging from disaccharide to hexasaccharide. These chitooligosaccharides were selectively deacetylated by two different chitin deacetylases followed by chemical N-trimethylation to obtain the desired TMG-chitotriomycin and a total of 13 TMG-chitotriomycin analogues in the longest linear sequence of 4 steps in over 12% total yields.
The activation of inert chemical bonds is an exciting area of research in chemistry because it enables the direct utilization of readily available starting materials and promotes atom- and step-economic synthesis. Undoubtedly, selectively activating and transforming multiple inert chemical bonds is an even more intriguing and demanding task in synthetic chemistry. However, due to its inherent complexity and extreme challenges, this endeavour is rarely accomplished. We report a copper-mediated complete cleavage and selective transformation of multiple inert chemical bonds of three easily available feedstocks, i.e., a sp 2C–H bond in indoles, three sp 3C–H bonds and one C–N bond in a methyl carbon atom in TMEDA, and the C≡N triple bond in CH 3CN. This reaction proceeds via tandem carbon and nitrogen atom transfer, and allows for the direct and efficient cyanation of indoles, presenting a simple and direct alternative for synthesizing 3-cyanoindoles.
Pd-mediated bioorthogonal cleavage reactions have been extensively utilized in the activation of prodrug molecules, precise regulation of protein function, and cellular engineering. However, the availability of cleavable "caging" groups is quite limited, and their application in nucleic acid modification has seldom been reported. Herein, we introduce a method based on Pd-catalyzed reduction amination of azides as a decaging strategy to activate the activity of biomolecules. We designed modifications on the bioactive sites with azides or their derivatives to mask the related biological function, followed by the release of biological activity through Pd-catalyzed NaBH 4 reduction amination reaction. This study has demonstrated that the strategy can effectively be used to activate bioactive molecules such as fluorescent probes, prodrugs, and to regulate the biological function of RNA, including reverse transcription extension, binding to ligands, and cleavage activity of the CRISPR-Cas system. All results confirm that this strategy provides an efficient and controllable "OFF to ON" biological switch, capable of achieving significant regulatory effects substoichiometrically, and is expected to be extended to other biological applications.
The strategy of removable glycosylation modification was used to overcome the low-efficiency problem encountered in the chemical synthesis of the mirror-image D-version of the immunoglobulin (Ig)-like domain of tropomyosin receptor kinase A ( DlgC TrkA), a protein molecule needed for mirror-image screening of D-peptide ligands targeting this cell membrane receptor. It was found that O-linked-β- N-acetyl- D-glucosamine (O-GlcNAc) modification at DSer 312, or DSer 320 can significantly improve the efficiency of DlgC TrkA synthesis and folding, while O-GlcNAc modification at DSer 330 showed barely any improvement. This study provides a new example demonstrating the power of the removable glycosylation modification strategy in the chemical synthesis and folding of difficult-to-obtain proteins. It also presents evidence that removable glycosylation modification at different sites would significantly affect the efficiency of protein folding promoted by this strategy.
A novel visible-light-induced radical cascade 6- endo cyclization of dienes ( N-(2-vinylphenyl)acryl amides) is developed utilizing α-carbonyl bromides as alkyl reagents. This approach affords an efficient way for synthesizing six-membered benzo-fused lactam derivatives with chemo- and regio-selectivity and good functional group tolerance. Primary, secondary, and tertiary bromides are well-compatible with this cascade cyclization reaction.
A visible light photocatalytic [3+2] cycloaddition of alkynes with readily accessible organic iodides as the C3 synthon is developed herein. By merging halogen atom transfer (XAT) and hydrogen atom transfer (HAT), alkyl/aryl iodides serve as a formal diradical precursor and add across C-C triple bonds to deliver a number of functionalized cyclopentanes in moderate to high yields with exceptional regio- and diastereoselectivity. A reductive radical-polar crossover mechanism, involving the cascade XAT, radical addition, 1, 5-HAT, polar effect-promoted 5-endo annulation, single electron transfer (SET) reduction, and protonation, may account for this unprecedented dehalogenative [3+2] cycloaddition. This work not only expands the repertoire of the traditional RATC methodology, but also provides a robust platform for the expedient assembly of cyclopentanes, a valuable structural motif in the realms of medicinal chemistry and material sciences.
The implementation of divergent protein engineering on the natural transaminase Vf-ω-TA led to the development of two effective mutants (M2 and M8), enabling the enzymatic synthesis of chiral amine precursors of Rivastigmine and Apremilast, respectively. The evolution of the enzymes was guided by crystal structures and a focused mutagenesis strategy, allowing them to effectively address the challenging ketone substrates with significant steric hindrance. Under the optimized reaction parameters, transamination proceeded smoothly in good conversions and with perfect stereochemical control (> 99% ee). These processes utilize inexpensive α-methylbenzylamine as an amine donor and avoid the continuous acetone removal and costly LDH/GDH/NADH systems.
Phthalides serve as core structures pervasive in a wide array of natural products and drug molecules, which display a diverse array of biological activities. We report herein a highly efficient dynamic kinetic resolution of 3-hydroxyphthalides by chiral isothioureas (ITUs) catalyzed asymmetric acylation, facilitating the effective synthesis of a variety of chiral phthalidyl esters with good yields and enantioselectivities. Notably, this reaction features mild reaction conditions, expansive substrate scope as well as good functional group compatibility. In addition, the practicality of this method is underscored by the large-scale synthesis, reduced catalyst loading experiment and the synthesis of the chiral phthalidyl ester prodrug.
Catalytic and green strategies for the synthesis of privileged scaffolds are synthetically appealing. We now report a radical-polar crossover (RPC)-enabled three-component cyclization of bromodifluoroalkyls with enaminones and 6-aminouraciles via a visible-light-induced domino cyclization. The reaction exhibited a broad substrate scope (> 40 examples) including complex molecules, which highlighted the utility of this strategy for the construction of a library of bioactive analogs.
HpnG plays a crucial role in the production of ribosylhopane, a key intermediate in the biosynthesis of bacteriohopanepolyol. Despite early extensive studies, the precise function of HpnG has remained elusive. Here, we report functional characterization of HpnG as a purine nucleoside phosphorylase, which converts adenosylhopane to phosphoribosylhopane in the presence of phosphate. HpnG demonstrates broad substrate specificity and impressive stability, making it a valuable enzymatic tool for applications in nucleoside processing and related biotechnology.
2, 3-Allenyl amines have shown wide applicability in biomedical and synthetic applications. Due to their enormous potential for applications, researchers have been dedicated to the development of methods for synthesizing 2, 3-allenyl amines. Herein, a palladium-catalyzed three-component reaction of 2-alkynyl-1, 4-diol dicarbonates, organoboronic acids, and nitrogen nucleophiles forming 2, 3-allenyl amines with excellent regio- and chemo-selectivity has been developed. Substrate compatibility and synthetic applications have been demonstrated. Control experiments supported a mechanism involving 1, 2, 3-triene-Pd species and methylene-π-allyl palladium species.
Many industries are plagued by economic losses and product failures caused by counterfeit goods. Therefore, advanced anti-counterfeiting techniques are continuously needed. In this study, we constructed a series of acid-base sensitive cyclic chalcone dyes A– F by modifying different electron-donating groups. Differences in acid sensitivity of different structures are well rationalised by NMR and theoretical calculations. Aniline is difficult to protonate than fatty amines, so there is a difference in fluorescence. Hiding and anti-counterfeiting of information is achieved by this phenomenon. Powder X and Y are the anti-counterfeit fluorescent powder containing montmorillonite and cyclic chalcone, which have orange fluorescence and the very similar appearance. However, under the influence of acid the Powder X containing triphenylamine modified cyclic chalcone shows red shifted fluorescence and Powder Y containing morpholino and diethylamino groups modified cyclic chalcone shows blue shifted fluorescence. Therefore, the anti-counterfeiting strategy based on cyclic chalcone is not only limited to UV-irradiated fluorescence development, but also has more colorization and pattern variations with the aid of acid developer. Data encryption and decryption of numbers, English alphabets and Chinese characters have been realized using A– F, which have great potential for practical applications.
Room-temperature sodium-sulfur (RT-Na/S) batteries display attractive potential in large-scale energy-storage, but their practical application was still restricted by the serious dissolution of polysulfides. Herein, supported by the constructing of interface engineering, the metal sulfide-carbon nanocomposite can be prepared with considerable electrochemical properties. Utilizing the double-helix structure of carrageenan-metal hydrogels as precursors, in-situ metal sulfide (M xS y) nanostructure/3D carbon aerogels (3D CAs) can be successfully constructed. Importantly, with the assistance of the vulcanization process, 3D carbon architecture was maintained in the composites and acted as a skeleton to optimize their structural stability. As the cathode of RT-Na/S batteries, ZnS/S@C and NiS 2/S@C delivered an excellent cycling stability and rate performance (179.8 mAh·g −1 at 20 A·g −1 after 10000 cycling for ZnS/S@C, 220.3 mAh·g −1 at 10 A·g −1 after 3000 cycling for NiS 2/S@C). The detailed investigation of mechanism revealed that the powerful adsorption for Na 2S 4 originated from 3D metal sulfide-carbon structure. The well-designed architecture of sulfide-carbon composites servers as an electrocatalyst to alleviate the shuttle effect of polysulfides, resulting in the long-term electrochemical stability. Given this, the work is expected to provide promising insights for designing advanced cathode materials for RT-Na/S batteries.
To better understand the impact of different anions on the structures and SCO properties of the Co II SCO complexes, six new complexes [Co(terpy-CH 2OH) 2]A 2·sol (terpy-CH 2OH = 4′-(hydroxymethyl)-2, 2′;6′, 2″-terpyridine, A = Br – ( 1, sol = 1.5H 2O), I – ( 2), N 3 – ( 3, sol = 2H 2O), H 3BCN – ( 4), OTf – ( 5), and TsO – ( 6, sol = 4H 2O·CH 3CN), have been synthesized and characterized. All six compounds consist of mononuclear [Co(terpy-CH 2OH) 2] 2+ cations and charge-balancing anions that differ in size, shape, and hydrogen bonding capacity. Complexes 1, 2, 3, and 6 displayed incomplete gradual SCO transitions, whereas 4 and 5 exhibited abrupt hysteretic spin transitions with loops of 12 and 16 K (250.0–262.0 K for 4, and 370.0–386.0 K for 5, respectively), closely resembling our previously reported complexes with SCN – and SeCN – anions. The occurrence of the order-disorder transition of the CH 2OH groups and their transition temperatures are determined by the size and hydrogen bonding capability of the anions. Remarkably, the transition temperatures of complexes with H 3BCN –, SCN –, OTf –, and SeCN – anions exhibit an upward trend as the size and mass of the anions increase, as confirmed through detailed single crystal structure analyses conducted in both high-spin and low-spin states for all four complexes.
Interfacing DNA oligonucleotides and DNA aptamers with gold nanoparticles has generated numerous functional hybrid materials for sensing, self-assembly and drug delivery applications. Our lab has been working in this area for 15 years. In this article, the current understanding of the adsorption of DNA to gold nanoparticles is summarized, and related applications in bioconjugation of DNA to gold surface is described. In addition, problems of using gold nanoparticles to signaling aptamer binding are discussed. Finally, re-selection of aptamers for previously reported targets using the library-immobilization method is reviewed.
The 21 st century has witnessed a continuous evolution in the development of boron-stereogenic chemistry. Since the 1990s, various innovations for the synthesis of tetracoordinate boron-stereogenic compounds, which exhibited great potential applications, have been demonstrated by synthetic chemists. This paper reviews the significant progress and recent advances towards the assembly of enantioenriched boron-stereogenic compounds, and hopes to shed light on new perspectives and inspire further research in this emerging field.
Due to the innate highly reactive properties and short life-time, organic free radicals can often serve as promoters or intermediates to engage in various radical transformations, which are often otherwise difficult to access by ionic pathway-based mechanisms. With the evolvement of radical chemistry, chiral radical catalyzed-transformations have recently emerged as an attractive and robust platform for synthesis of chiral molecules of interest. Herein, we highlight several creative and strategic advances in chiral radical catalyst design, cyclization reaction achievements, and future challenges.