A General Photoactive H-Bonding EDA Complex Model Drives the Selective Hydrothiolation and Hydroxysulfenylation of Carbonyl Activated Alkenes.

Excitation of photoactive electron donor-acceptor (EDA) complexes to generate radical is a promising approach in radical chemistry. In this study, we introduce a new model of H-bonding EDA complexes for the selective hydrothiolation and hydroxysulfenylation of carbonyl-activated alkenes with diverse thiols under visible light conditions. The reliability of this H-bonding EDA complex model has been confirmed by meticulous experimental and theoretical calculations. Mechanistic investigations have revealed the significant influence of the solvent in determining whether the excitation of photoactive H-bonding EDA complex leads to charge transfer (CT) or energy-charge transfer (En-CT), thereby controlling Markovnikov and anti-Markovnikov selectivity. Notably, the Quantum Theory of Atoms in Molecules (QTAIM) analysis clearly shows that the excited state of the C=O-H-S EDA complex involves closed-shell partially covalent interactions.

Base-promoted one-pot three-component desulphurization cross-coupling access to 4-cyanoimidazole.

A novel, straightforward, and scalable base-mediated one-pot three-component desulphurization cross-coupling strategy is reported for the synthesis of 4-cyanoimidazole derivatives. Over 35 examples are provided and achieved yields exceeding 85%. Notably, the majority of these readily available compounds can be isolated through simple filtration, thereby circumventing the need for laborious column chromatography. Besides, the present protocol can be scaled up to 10 mmol with a yield of 87%, demonstrating promising potential for industrial applications.

2D Ag Ion-Loaded Anionic Nanosheets for Polymer-Based Film with Durable Antibacterial Activities.

Silver (Ag) has been demonstrated to have excellent performance to kill bacteria, fungi, and some viruses because it can release positively charged Ag ions with highly antibacterial and antifungal activities. However, effectively controlling the slow release of Ag ions is the key to preparing high-performance Ag-based antibacterial agents, which remains a challenge. In this work, we have developed a new Ag-based antibacterial agent composed of Ag ions loaded on 2D anionic 2D Sb3P2O14 3- nanosheets (denoted as Ag-Sb3P2O14). 2D anionic nanosheets not only adsorb a large amount of Ag ions but also control their slow release through electrostatic interaction between nanosheets and Ag ions. 2D Ag-Sb3P2O14 nanofillers enable excellent high antibacterial activities for the poly(vinylidene fluoride) (PVDF) film composites against microorganisms including Escherichia coli and Staphylococcus aureus. Moreover, the PVDF membrane with 5 wt % 2D Ag-Sb3P2O14 nanofillers can kill almost all bacterial after 50 times washing, demonstrating its excellent durable antibacterial activities. This work opens up a new and promising route to durable Ag-based antibacterial agents for polymer-based composites.

An electrochemical gram-scale protocol for pyridylation of inert N-heterocycles with cyanopyridines.

Here, we present a protocol to decyanopyridate inert N-heterocycles access to N-fused heterocycles via the mechanism of dual proton-coupled electron transfer (PCET). We describe a detailed guide to performing an electrochemical gram-scale protocol for decyanopyridation of inert N-heterocycles. The desired pyridylated quinolone is synthesized in a 5.0 mmol scale with a yield of 76%. The protocol is limited to cyanopyridines. For complete details on the use and execution of this protocol, please refer to Niu et al. (2022).

Hydrophosphorylation of electron-deficient alkenes and alkynes mediated by convergent paired electrolysis.

A straightforward and practical strategy for hydrophosphorylation of electron-deficient alkenes and alkynes to access γ-ketophosphine oxides, enabled by a convergent paired electrolysis (CPE) in the absence of a metal, base, and redox reagent, has been described. Mechanistic studies have revealed that the diarylphosphane oxides play the dual role of a phosphorus radical precursor and hydrogen donor in this transformation.

Electrochemical ammonium-cation-assisted pyridylation of inert N-heterocycles via dual-proton-coupled electron transfer.

A straightforward and practical strategy for pyridylation of inert N-heterocycles, enabled by ammonium cation and electrochemical, has been described. This protocol gives access to various N-fused heterocycles and bidentate nitrogen ligand compounds, through dual-proton-coupled electron transfer (PCET) and radical cross-coupling in the absence of exogenous metal and redox reagent. It features broad substrate scope, wide functional group tolerance, and easy gram-scale synthesis. Various experiments and density functional theory (DFT) calculation results show the mechanism of dual PCET followed by radical cross-coupling is the preferred pathway. Moreover, ammonium salt plays the dual role of protonation reagent and electrolyte in this conversion, and the resulting product 9-(pyridin-4-yl)acridine compound can be used for fluorescence recognition of Fe2+ and Pd2+ with high sensitivity.

Electroreductive C3 Pyridylation of Quinoxalin-2(1H)-ones: An Effective Way to Access Bidentate Nitrogen Ligands.

The construction of functional N-containing active biomolecules and bidentate nitrogen ligands by electroreductive pyridylation of N-heteroaromatics is an eye-catching task and challenge. A simple and practical electroreductive-induced C3 pyridylation of quinoxalin-2(1H)-ones with readily available cyanopyridines is reported. More than 36 examples are supplied, and the reaction performed in >95% yield. The present protocol provides a convenient, efficient, and gram-scale synthesis strategy for a series of new types of potential bidentate nitrogen ligands.

Electrochemical-Induced Transfer Hydrogenation of Imidazopyridines with Secondary Amine as Hydrogen Donor.

Electrochemical-induced transfer hydrogenation (TH) of N-heteroaromatic to construct biologically active functional molecule is an appealing and yet challenging task. We report herein the first selective transfer hydrogenation of imidazopyridine derivatives with secondary amines as the hydrogen donors under electrochemical conditions. The successful conversion of cathode transfer hydrogenation depends on the solvation effect. Importantly, such electrochemical-induced transfer hydrogenation can be easily amplified with excellent efficiency.

Synthesis of Substituted Naphtho[1,8-bc]thiopyrans by Sulfhydryl-Directed Rhodium-Catalyzed peri-Selective C-H Bond Activation and Cyclization of Naphthalene-1-thiols.

The sulfhydryl-directed peri-selective C-H bond activation and tandem cyclization of naphthalene-1-thiols with alkynes proceed efficiently. Most products of naphthothiopyrans with various substituents are achieved in good yields under rhodium catalysis. This protocol has some advantages over the traditional methods in synthesizing naphtho[1,8-bc]thiopyrans in terms of stable coupling substrates, simple operation, peri-selectivity, and atom and step economy.

Regenerated keratin-encapsulated gold nanorods for chemo-photothermal synergistic therapy.

Gold nanorods (AuNRs) have been widely applied to photothermal therapy against cancer. However, the chemically synthesized AuNRs such as that via seed-mediate method usually demonstrated a high cytotoxicity due to the existence of cetyltrimethylammonium bromide (CTAB) coating. In this work, keratin, a family of cysteine-rich structural fibrous proteins was used for the first time to encapsulate AuNRs by a simple mixing method. Compared with CTAB-AuNRs, the keratin-encapsulated AuNRs (AuNRs@Kr) showed an improved colloid stability and good biocompatibility including low cytotoxicity and hemolytic effect. Moreover, AuNRs@Kr exhibited great potential as drug carriers with redox-responsive drug release behavior, due to the high concentration of disulfide crosslinking in keratin coating, and the DOX-loaded AuNRs@Kr demonstrated higher chemo-photothermal synergistic therapy efficiency against 4T1 cells compared with either free DOX or AuNRs@Kr alone, suggesting a promising nanoplatform for cancer therapy.

Investigation on Reaction Sequence and Group Site of Citric Acid with Cellulose Characterized by FTIR in Combination with Two-Dimensional Correlation Spectroscopy.

Cotton fabrics are prone to wrinkles and can be treated with citric acid (CA) to obtain good anti-wrinkle properties. However, the yellowing of the CA-treated fabrics is one big obstacle to the practical application of citric acid. The changing sequence order of CA anhydride and unsaturated acid (the reason for yellowing), such as aconitic acid (AA), has not been investigated. Herein, Fourier transform infrared (FTIR) spectroscopy, two-dimensional correlation spectroscopy (2Dcos), and Gaussian calculation were employed to characterize the reaction mechanism between CA with cellulose. FTIR spectra of the CA-treated fabrics heated under different temperatures were collected and further analyzed with 2Dcos. The results indicated the changing sequence order: 1656 cm-1→1784 cm-1→1701 cm-1, ("→" means earlier than), i.e., unsaturated acid→anhydride→ester. Moreover, a change of Gibbs free energy (ΔG) showed that trans-AA (ΔG = -22.10 kJ/mol) is more thermodynamically favorable to be formed than CA anhydride 1 (ΔG = -0.90 kJ/mol), which was proved by Gaussian computational modeling. By taking cellobiose as a model of cellulose, the ΔG results proved that O(6)-H(6) on the glucose ring is the most likely hydroxyl to react with anhydride originated from CA or AA, especially with the terminal carbonyl group.

Sulfhydryl-Directed Iridium-Catalyzed C-H/Diazo Coupling and Tandem Annulation of Naphthalene-1-thiols.

The first sulfhydryl-directed iridium-catalyzed C-H/diazo coupling and tandem annulation of naphthalene-1-thiols has been developed. The framework of naphtho[1,8-bc]thiopyrans was constructed in a one-step reaction with good yields. This transformation provides a practical synthetic route for the widely used naphtho[1,8-bc]thiopyran derivatives.

Photothermal and Moisture Actuator Made with Graphene Oxide and Sodium Alginate for Remotely Controllable and Programmable Intelligent Devices.

Functional materials with energy storage and conversion properties have been useful for actuating devices. Here, a new kind of torsional fiber-based actuator including graphene oxide (GO) and natural sodium alginate was prepared by traditional wet spinning and twisting methods, during which the fiber structure was reconstructed, and the mechanical energy was prestored. When the twisted GO/SA (graphene oxide/sodium alginate) fiber was stimulated by infrared light or moisture, the torsional structure of the fiber was activated instantaneously to generate rapid and reversible rotational motion, thus realizing the automatic release and re-storage process of rotational kinetic energy. In addition, the full revolutions of the twisted GO/SA fiber have no attenuation after 100 reversible rotations when stimulated by moisture, which proves the excellent rotational stability. Due to its excellent flexibility and wettability, the twisted GO/SA fiber can be woven into a network or prepared into a series of programmable intelligent devices, which is of great significance for future flexible intelligent electronic devices.

Disinfectant Performance of a Chlorine Regenerable Antibacterial Microfiber Fabric as a Reusable Wiper.

Rechargeable disinfectant performance of a microfiber fabric grafted with a halamine precursor, 3-allyl-5,5-dimethylhydantoin (ADMH), was tested in an actual use situation in a university student dining hall. The precursor was successfully incorporated onto the surfaces of polyester fibers by using a radical graft polymerization process through a commercial finishing facility. The N⁻H bonds of ADMH moieties on the fibers can be converted to biocidal N⁻Cl bonds, when the fabrics are washed in a diluted chlorine bleach containing 3000 ppm available chlorine, providing a refreshable disinfectant function. By wiping the surfaces of 30 tables (equivalent to 18 m²) with wet chlorinated fabrics, both Staphylococcus aureus and Escherichia coli in concentrations of 105 CFU/mL were totally killed in a contact time of 3 min. The disinfectant properties of the fabrics were still superior after 10 times successive machine washes (equivalent to fifty household machine washes), and rechargeable after wiping 30 tables before each recharge. Recharging conditions, such as temperature, time, active chlorine concentration and pH value of sodium hypochlorite solution, as well as the addition of a detergent, were studied. The product has the potential to improve public safety against biological contaminations and the transmission of diseases.

Catalytic and ionic cross-linking actions of l-glutamate salt for the modification of cellulose by 1,2,3,4-butanetetracarboxylic acid.

The sodium l-glutamate is reported as an efficient catalyst for the cross-linking between 1,2,3,4-butanetetracarboxylic acid (BTCA) and cellulose. Results presented ester absorbance of the treated fabrics strongly increased in the presence of the homemade l-glutamate salt, a mixture of l-glutamic acid (LGA) and NaOH at a specific ratio. Importantly, anti-wrinkle properties of the treated fabrics were significantly improved. Based on the relative concentration calculation, l-glutamate promoted the reaction of BTCA with cellulose by accelerating the formation of BTCA anhydrides and the esterification of anhydrides with cellulose. Besides, the improved anti-wrinkle property was partially attributed to the fact that the generated LGA reacted with cellulose and formed ionic cross-linking networks through amino groups with carboxyl groups in BTCA, which was confirmed by the Fourier transform infrared spectra and the computational calculations. Through detailed comparisons, l-glutamate catalyzed fabrics showed as good durability as sodium hypophosphite, indicating a possible alternative for phosphorus-containing catalysts.

Cp*Co(III)-Catalyzed C-H Acylmethylation of Arenes by Employing Sulfoxonium Ylides as Carbene Precursors.

A Cp*Co(III)-catalyzed C-H bond functionalization of a range of arenes by employing sulfoxonium ylides as carbene precursors instead of diazo compounds and other carbene precursors has been established. This reaction is highly efficient without any additive, possesses high step and atom economies, and tolerates a range of functional groups.

A one-step inkjet printing technology with reactive dye ink and cationic compound ink for cotton fabrics.

In the paper, a one-step inkjet printing technology with reactive dye ink and cationic compound ink for cotton fabric was reported. Cationic ink of 3-chloro-2-hydroxypropyltrimethyl ammonium chloride (CHPTAC) and reactive dye ink were printed simultaneously on the sized cotton fabric, and then the sample was steamed. Response surface methodology (RSM) was used to investigate the influences of steam conditions on the K/S value and dye fixation rate. The K/S value, dye fixation rate, staining of the white ground and colorfastness of cotton fabrics treated with different inkjet printing methods were compared. X-ray photoelectron spectrometer (XPS) analysis and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrum confirmed the reaction of CHPTAC to cotton treated by one-step inkjet printing technology. And a suggested reaction process of the one-step inkjet printing method was proposed through Gaussian calculation.

Multistimulus Responsive Actuator with GO and Carbon Nanotube/PDMS Bilayer Structure for Flexible and Smart Devices.

Smart devices with abilities of perceiving, processing, and responding are attracting more and more attentions due to the emerging development of artificial intelligent systems, especially in biomimetic and intelligent robotics fields. Designing a smart actuator with high flexibility and multistimulation responsive behaviors to simulate the movement of creatures, such as weight lifting, heavy objects carrying via simple materials, and structural design is highly demanded for the development of intelligent systems. Herein, a soft actuator that can produce reversible deformations under the control of light, thermal, and humidity is fabricated by combining high photothermal properties of CNT/PDMS layer with the natural hydrophilic GO layer. Due to the asymmetric double-layer structure, the novel bilayer membrane-based actuator showed different bending directions under photothermal and humidity stimulations, resulting in bidirectional controllable bending behaviors. In addition, the actuation behaviors can be well controlled by directionally aligning the graphene oxide onto carbon nanotube/PDMS layer. The actuator can be fabricated into a series of complex biomimetic devices, such as, simulated biomimetic fingers, smart "tweezers", humidity control switches, which has great potential applications in flexible robots, artificial muscles, and optical control medical devices.

Bleaching of cotton fabric with tetraacetylhydrazine as bleach activator for H2O2.

Tetraacetylhydrazine (TH) as bleach activator for H2O2 cotton bleaching was synthesized and characterized by 1H NMR, 13C NMR and MS spectra. TH has better solubility than that of TAED. The CIE whiteness index (WI), H2O2 decomposition rate and bursting strength were employed to investigate the performance of H2O2/TH bleaching system. By addition of TH, WI and H2O2 decomposition rate increased significantly at 70 °C. Bleaching temperature, NaHCO3 concentration and bleaching time were also discussed in detail and the loss of bursting strength is not clear. By using benzenepentacarboxylic acid (BA) as a fluorescent probe for hydroxyl radical detection, the bleaching process of H2O2/TH system was investigated. Acetylhydrazine and diacetylhydrazine were also utilized to further confirm the process. In addition, bimolecular decomposition was investigated by using 9,10-dimethylanthracene (DMA) as fluorescent probe of 1O2. Based on these experimental results, the bleaching mechanism of H2O2/TH system was proposed.

Effects of divalent anionic catalysts on cross-linking of cellulose with 1,2,3,4-butanetetracarboxylic acid.

1,2,3,4-Butanetetracarboxylic acid (BTCA) can efficiently esterify cellulose with pyrophosphoric acid (PPA) as a catalyst to remove protons of reaction intermediates. However, valence and relative concentration ratio (RCR) of catalyst anions correlating to pH of finishing bath played a critical role in the reactions. Results here indicated that wrinkle recovery angle, tensile strength retention and ester absorbance of fabrics treated at pH of 2.8 showed higher values. It was a competing reaction for BTCA molecules to esterify or depolymerize cellulose. Importantly, divalent PPA anions were more efficient than monovalent ones in catalyzing the esterification between anhydrides and cellulose, which was confirmed by FTIR results and two-dimensional correlation spectroscopy analyses and by the RCRs of PPA anions and their changing rates versus pH. Furthermore, the higher catalytic efficiency of divalent anions was proved by the selected model catalysts. Meaningfully, the fabrics treated at pH≤3.2 presented good durability.