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The lack of catalytic stereoselective approaches for producing 1,2- cis S -furanosides emphasizes the critical need for further research in this area. Herein, we present a stereoselective S -furanosylation method, utilizing a 4,7-dipiperidine-substituted phenanthroline catalyst. This developed protocol fills a gap in the field, enabling the coupling of cysteine residues and thiols with furanosyl bromide electrophiles. The process allows for stereoselective access to 1,2- cis S -furanosides. Through computational and experimental investigations, thiol is found to be less reactive than alcohol but exhibits greater stereoselectivity. The 1,2- cis stereoselectivity of O -products depends on the nature of the electrophile, while S -products are obtained with excellent 1,2- cis stereoselectivity, irrespective of the furanose structure. The displaced bromide ion from the glycosyl electrophile influences the reaction's reactivity and stereoselectivity. Alcohol-OH forms a stronger hydrogen bond with bromide ion than thiol-SH, contributing to the difference in their reactivity. The energy difference between forming S -furanoside and O -furanoside transition states is 3.7 kcal mol -1 , supporting the increased reactivity of alcohol over thiol. The difference in transition state energies between the major and minor S -product is greater than that for the major and minor O -product. This is consistent with experimental data showing how thiol is more stereoselective than alcohol. The catalyst and reaction conditions utilized for the generation of 1,2- cis O -furanosides in our prior studies are found to be unsuitable for the synthesis of 1,2- cis S -furanosides. In the present study, a highly reactive phenanthroline catalyst and specific reaction conditions have been developed to achieve stereoselective S -linked product formation.

We investigate hydrogen sorption on open copper sites in various ligand coordinations of metal-organic frameworks (MOFs), including the triangular T(CuL 3 ) in MFU-4l, the linear L(CuL 2 ) in NU2100, and the paddlewheel P(CuL 4 ) 2 in HKUST-1 from an electronic structure perspective using DFT calculations. The ligand-field-induced splitting of d states and spd hybridizations in copper are thoroughly examined. The hybridization between Cu s, p, and d orbitals occurs in various forms to optimize the Coulomb repulsion of different ligand fields. Despite the Cu + oxidation state, which is typically conducive to strong Kubas interactions with hydrogen molecules, the vacant spd z 2 hybrid orbitals of the open copper site in the L(CuL 2 ) coordination are unsuitable for facilitating electron forward donation, thereby preventing effective hydrogen adsorption. In contrast, the vacant spd z 2 hybrid orbitals in the T(CuL 3 ) and P(CuL 4 ) 2 coordinations can engage in electron forward donations, forming bonding states between the Cu spd z 2 and H 2 σ bonding orbitals. The forward donation in the T(CuL 3 ) configuration is significantly stronger than in the P(CuL 4 ) 2 configuration due to both the lower energy of the vacant orbitals and the larger contributions of p and d z 2 characters to the hybrid orbital. Additionally, the occupied Cu pd xz / yz and pd x 2 - y 2 hybrid orbitals in the T(CuL 3 ) configuration promote electron back donation to the H 2 σ* antibonding orbital, leading to the formation of π bonding states. In the P(CuL 4 ) 2 coordination, the repulsion from the electron density distributed over the surrounding ligands prevents the H 2 molecule from approaching the copper center closely enough for the back donation to occur. The complete Kubas interaction, involving both forward and back electron donations, results in a large dihydrogen-copper binding energy of 37.6 kJ mol -1 in the T(CuL 3 ) coordination. In contrast, the binding energy of 10.6 kJ mol -1 in the P(CuL 4 ) 2 coordination is primarily driven by electrostatic interactions with a minor contribution of the Kubas-like forward donation interaction. This analysis highlights the pivotal role of coordination environments in determining the hydrogen sorption properties of MOFs., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Alzheimer's disease is one of the causes associated with the early stages of dementia. Nowadays, the main treatment available is to inhibit the actions of the acetylcholinesterase (AChE) enzyme, which has been identified as responsible for the disease. In this study, computational methods were used to examine the structure and therapeutic ability of chemical compounds extracted from Millettia brandisiana natural products against AChE. This plant is commonly known as a traditional medicine in Vietnam and Thailand for the treatment of several diseases. Furthermore, machine learning helped us narrow down the choice of 85 substances for further studies by molecular docking and molecular dynamics simulations to gain deeper insights into the interactions between inhibitors and disease proteins. Of the five top-choice substances, γ-dimethylallyloxy-5,7,2,5-tetramethoxyisoflavone emerges as a promising substance due to its large free binding energy to AChE and the high thermodynamic stability of the resulting complex.

Wound healing is vital to maintain the physiological functions of the skin. The most common treatment is the use of a dressing to cover the wound and reduce infection risk and the rate of secondary injuries. Modern wound dressings have been the top priority choice for healing various types of wounds owing to their outstanding biocompatibility and biodegradability. In addition, they also maintain temperature and a moist environment, aid in pain relief, and improve hypoxic environments to stimulate wound healing. Due to the different types of wounds, as well as the variety of advanced wound dressing products, this review will provide information on the clinical characteristics of the wound, the properties of common modern dressings, and the in vitro , in vivo as well as the clinical trials on their effectiveness. The most popular types commonly used in producing modern dressings are hydrogels, hydrocolloids, alginates, foams, and films. In addition, the review also presents the polymer materials for dressing applications as well as the trend of developing these current modern dressings to maximize their function and create ideal dressings. The last is the discussion about dressing selection in wound treatment and an estimate of the current development tendency of new materials for wound healing dressings., Competing Interests: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article., (This journal is © The Royal Society of Chemistry.)

Novel ciprofloxacin composite imprinted materials are synthesized by using co-precipitation polymerization of dual functional monomers (methacrylic acid and 2-vinylpyridine) and polystyrene- co -divinylbenzene. The intermolecular interactions between monomers and template are evaluated by molecular modeling analysis. The physicochemical properties of the obtained polymers are characterized using FT-IR, TGA, and SEM. Batch adsorption experiments are used to investigate adsorption properties (kinetic, pH, and isotherm). These polymers are employed to prepare the solid phase extraction cartridges, and their extraction performances are analyzed by the HPLC-UV method. DFT calculations indicate that hydrogen bonding and π-π stacking are the driving forces for the formation of selective rebinding sites. The obtained polymers exhibit excellent adsorption properties, including fast kinetics and high adsorption capacity (up to 10.28 mg g -1 ) with an imprinted factor of 2.55. The Scatchard analysis indicates the presence of specific high-affinity adsorption sites on the imprinted polymer. These absorbents are employed to extract CIP in river water with recoveries in the range of 65.97-119.26% and the relative standard deviation of 3.59-14.01%. Furthermore, the used cartridges could be reused at least eight times without decreasing their initial adsorption capacity., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Block copolymer (BCP) thin films prepared by dip-coating are increasingly investigated, owing to the many promising application areas, the facility, and the industrial scalability of this technique. Yet, the effect of different dip-coating parameters on BCP nanostructure formation is still underdeveloped and the results of previous literature are limited to a few block copolymers. Here, we study the effect of the withdrawal rate and solvent selectivity on the morphology evolution of dip-coated polystyrene- b -poly(ethylene oxide) thin films by applying a wide range of dip-coating speeds and altering the volume ratio of the tetrahydrofuran-water solvent system. The dip-coated films were characterized using atomic force microscopy and ellipsometry. The nanodomain morphology, its feature sizes, its spanning, and the degree of ordering were investigated with regard to different dip-coating parameters. Notably, we have obtained a hexagonally packed BCP pattern with long-range order without the need for post-annealing processes. Overall, a solid understanding of the parameters affecting the formed surface patterns and their interplay was attained and explained, extending the knowledge of this field to more materials., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The main protease (Mpro) of the novel coronavirus SARS-CoV-2, which has caused the COVID-19 pandemic, is responsible for the maturation of its key proteins. Thus, inhibiting SARS-CoV-2 Mpro could prevent SARS-CoV-2 from multiplying. Because new inhibitors require thorough validation, repurposing current drugs could help reduce the validation process. Many recent studies used molecular docking to screen large databases for potential inhibitors of SARS-CoV-2 Mpro. However, molecular docking does not consider molecular dynamics and thus can be prone to error. In this work, we developed a protocol using free energy perturbation (FEP) to assess the potential inhibitors of SARS-CoV-2 Mpro. First, we validated both molecular docking and FEP on a set of 11 inhibitors of SARS-CoV-2 Mpro with experimentally determined inhibitory data. The experimentally deduced binding free energy exhibits significantly stronger correlation with that predicted by FEP ( R = 0.94 ± 0.04) than with that predicted by molecular docking ( R = 0.82 ± 0.08). This result clearly shows that FEP is the most accurate method available to predict the binding affinity of SARS-CoV-2 Mpro + ligand complexes. We subsequently used FEP to validate the top 33 compounds screened with molecular docking from the ZINC15 database. Thirteen of these compounds were predicted to bind strongly to SARS-CoV-2 Mpro, most of which are currently used as drugs for various diseases in humans. Notably, delamanid, an anti-tuberculosis drug, was predicted to inhibit SARS-CoV-2 Mpro in the nanomolar range. Because both COVID-19 and tuberculosis are lung diseases, delamanid has higher probability to be suitable for treating COVID-19 than other predicted compounds. Analysis of the complexes of SARS-CoV-2 Mpro and the top inhibitors revealed the key residues involved in the binding, including the catalytic dyad His14 and Cys145, which is consistent with the structural studies reported recently., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Studies of S -linked glycoconjugates have attracted growing interest because of their enhanced chemical stability and enzymatic resistance over O -glycoside counterparts. We here report a facile approach to access α-1,2- cis-S -linked glycosides using triflic acid as a catalyst to promote the glycosylation of a series of thiols with d-glucosamine, galactosamine, glucose, and galactose electrophiles. This method is broadly applicable for the stereoselective synthesis of S -linked glycopeptides, oligosaccharides and glycolipids in high yield and excellent α-selectivity. Many of the synthetic limitations associated with the preparation of these S -linked products are overcome by this catalytic method., (This journal is © The Royal Society of Chemistry 2019.)

Heparanase is an enzyme which cleaves heparan sulfate (HS) polysaccharides of the extracellular matrix. It is a regulator of tumor behavior, plays a key role in kidney related diseases and autoimmune diabetes. We report herein the use of computational studies to extract the natural HS-heparanase interactions as a template for the design of HS mimicking glycopolymers. Upon evaluation, a glycopolymer with 12 repeating units was determined to be the most potent inhibitor and to have tight-binding characteristics. This glycopolymer also lacks anticoagulant activity.

The optical spectra in the UV-VIS region of the hydrated doubly charged tetramer Ag4(2+) and hydrated multiply charged hexamer Ag6(p+) silver clusters encapsulated inside the sodalite cavity of an LTA-type zeolite have been systematically predicted using DFT, TD-DFT and CASSCF/CASPT2 methods. The optical behaviour of the model hydrated clusters [Ag6(H2O)8(Si24H24O36)](p+) is very sensitive to their charge. Among the cations [Ag6(H2O)8(Si24H24O36)](p+), only the embedded hydrated quadruply charged silver hexamer [Ag6(H2O)8(Si24H24O36)](4+) shows a strong absorption band at ∼420 nm (blue light) and emits light in red color. The absorption spectrum of the hydrated doubly charged silver tetramer cluster [Ag4(H2O)m(Si24H24O36)](2+), which shifts slightly and steadily with the increasing amount of interacting water molecules to longer wavelengths, has a strong peak in the blue region. The water environment forces the silver tetramer to relocate into one side of the cavity instead of at its center as in the case of the non-hydrated [Ag4(Si24H24O36)](2+) cluster. Water molecules act as ligands significantly splitting the energy levels of excited states of the Ag4(2+) and Ag6(4+) clusters. This causes the absorption spectra of the clusters to broaden and the emission to shift to the green-yellow and red part of the visible region.

Employing newly synthesized di-substituted tri-phenyl amine (HMP-9) and carbazole (HMP-11) dyes (with limited acidic carboxyl anchor groups), a power conversion efficiency as high as 7.03% in ZnO nanocrystallite (NC)-based dye-sensitized solar cells (DSSCs) is achieved. The specific molecular designs of HMP-09 and HMP-11 consisting of with and without hexyloxy spacer groups, and added tri-phenyl amine or 9-phenyl-9H-carbazole donor groups, respectively, attached on the ancillary ligands are advantageous, evidenced from electrochemical impedance spectroscopy measurements, for ZnO NC-based DSSCs.

Optical properties of silver Ag(n) nanoclusters are demonstrated to be dependent on their size, structure and charge state. It is found that when being contained in the sodalite cavity of LTA zeolite the tetradecanuclear hexacation silver cluster Ag14(6+) is stable. Its lower-lying states and optical spectrum are theoretically determined using the quantum chemical TD-DFT method. Its ground state possesses an outer-shell electron configuration of A1g(2)T2g(6) mimicking the s(2)p(6) valence of noble gas atoms. These frontier orbitals are constructed from 5s,5p(Ag)-AOs with contributions from framework oxygen atoms. Light absorption of Ag14(6+) embedded in the sodalite cage which is characterized by strong peaks centered at 331 and 476 nm (transitions 5s,p(Ag) → 5s,p(Ag)) leads to much longer wavelength emission. The sodalite cage, as a container, stabilizes the central Ag14(6+) cluster by electrostatic attraction. The absorption spectrum of the isovalent neutral Ag8 cluster embedded inside the same sodalite cavity is also simulated using TD-DFT and CASPT2 methods. This absorption spectrum which is similar to that of the Ag14(6+) cluster has two absorption bands in the near UV and visible regions.

Formal synthesis of mycothiol has been developed via nickel-catalyzed α-glycosylation of the C(1)-hydroxyl group of D-myo-inositols with C(2)-N-substituted benzylideneamino N-phenyl trifluoroacetimidate donors. The pseudo-oligosaccharides were obtained in good yield and with excellent α-selectivity. Removal of the C(2)-N-2-trifluoromethylphenyl-benzylidene group under mild conditions provides a pseudo-disaccharide, completing the formal synthesis of mycothiol.

We report the chiral diene ligated rhodium-catalyzed dynamic kinetic asymmetric transformation (DYKAT) of racemic secondary allylic trichloroacetimidates with a variety of N-methyl anilines, providing allylic N-methyl arylamines in high yields, regioselectivity, and enantiomeric excess. The rhodium-catalyzed DYKAT method addresses limitations previously associated with this particular class of aromatic nitrogen nucleophiles.