Asymmetric Synthesis, Antifungal Activity and Molecular Modeling of Iodiconazole Isomers

Iodiconazole is a novel antifungal agent that was developed in its racemic form. In order to investigate the ef- fects of the chiral center on the antifungal activity, R- and S-isomers of iodiconazole were prepared on the basis of the asymmetric Sharpless epoxidation. （S）-Iodiconazole was proved to have better antifungal activity than the （R）- isomer. The binding modes of the two isomers with lanosterol 14~z-demethylase were clarified by molecular dock- ing.     

Effective synthesis of benzyl halides triggered by in situ prepared hypervalent halides

An effective approach for the direct benzylhalogenation with in situ generation of hypervalent halides has been developed.A variety of benzyl halides are produced in moderate to excellent yields(up to 99%) with high regioselectivities.UV absorption spectrum is employed to detect the formation of ferr-butyl hypoiodite.     

Enhancing electrochemical performance of LiFePO4 by in situ reducing flexible graphene

Well-dispersed graphene materials reduced by Ac under hydrothermal condition were used as conductive additives to improve intrisic disadvantage of promising LiFePO₄ battery materials, which was synthesized at surface of graphene sheets. The as-prepared LiFePO₄/graphene composites were characterized by X-ray powder diffraction (XRD), scan electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge tests. The results show that, compared with conventional LiFePO₄ platelets, the composite deliver excellent electrochemical performances, due to flexible graphene-based porous conducting network. We believe that such a facile process will provide a new pathway for further enhancing its energy storage efficiency.     

Electrogenerated Fe(I) Porphyrins: Efficient Electrocatalysts for Reductive Dechlorination of DDT in N,N′‐Dimethylformamide

Two iron(I) porphyrins were electrogenerated and then utilized as catalysts for the reductive dechlorination of 1,1‐bis(4‐chlorophenyl)‐2,2,2‐trichloroethane (DDT) in N,N′‐dimethylformamide. No reaction is observed between DDT and the Fe(III) or Fe(II) forms of the porphyrin, but the electrogenerated Fe(I) porphyrin efficiently catalyzes the electroreduction of DDT to give (1,1‐bis(4‐chlorophenyl)‐2,2‐dichloroethane) DDD, (1,1‐bis(4‐chlorophenyl)‐2,2‐dichloroethylene) DDE and (1,1‐bis(4‐chlorophenyl)‐2‐dichloroethane) DDMU as determined by GC‐MS analysis. The reductive dechlorination was monitored by electrochemistry, controlled potential electrolysis and spectroelectrochemistry and a mechanism for the reaction involving the reduced porphyrins and DDT is proposed. Comparisons are also made between the catalytic properties of metalloporphyrins containing iron, cobalt and manganese central metal ions under the same solution conditions.     

Water Clusters: Through Which Water Capsules Were Connected to Form Supramolecular Chains

A crystal structure of {H₂O@CB[5]·(NH₄PF₆)₂}·9(H₂O) which consists of supramolecular chains self-assembled by water clusters and water capsules alternately was demonstrated. A water molecule is encapsulated in the cavity of CB[5] whose portals are occupied by two NH₄ ⁺, resulting in the formation of water capsule. The water clusters are made up of (H₂O)₄ and (H₂O)₅ clusters. The (H₂O)₄ cluster forms zigzag line and (H₂O)₅ features “Y-shape” structure. Moreover, anion channels consisting of six parallel supramolecular chains are occupied by PF₆ ^?.     

Computational investigation of the heat of formation, detonation properties of furazan-based energetic materials

The heats of formation (HOFs) for a series of furazan-based energetic materials were calculated by density functional theory. The isodesmic reaction method was employed to estimate the HOFs. The result shows that the introductions of azo and azoxy groups can increase the HOF, but the introduction of azo group can increase the more HOF, when compared with azoxy group. The detonation velocities and detonation pressures of the furazan-based energetic materials are further evaluated at B3LYP/6-31G* level. Dioxoazotetrafurazan and azoxytetrafurazan may be regarded as the potential candidates of high-energy density materials because of good detonation performance. In addition, there are good linear correlations between OB and detonation velocities, and OB and detonation pressures. The energy gaps between the HOMO and LUMO of the studied compounds are also investigated. These results provide basic information for the molecular design of novel high-energy density materials.     

Determination of acetamiprid partial-intercalative binding to DNA by use of spectroscopic, chemometrics, and molecular docking techniques

Acetamiprid (ACT) is an insecticide widely used for controlling a variety of insect pests. The binding mode associated with calf thymus DNA (ctDNA) upon interaction with ACT was determined using spectroscopic, chemometrics, and molecular docking techniques to clarify the interaction mechanism at the molecular level. Fluorescence titration suggested that the fluorescence quenching of ACT by ctDNA is a static procedure. The binding constants between ACT and ctDNA at different temperatures were calculated to be of the order 10³?10⁴ L mol^?1. The positive values of enthalpy and entropy change suggested that the binding process is primarily driven by hydrophobic interactions. Multivariate curve resolution?alternating least squares (MCR?ALS), a chemometrics approach, was used to resolve the expanded UV–visible spectral data matrix. The concentration profiles and the spectra for the three reaction components (ACT, ctDNA, and ACT?ctDNA complex) of the system, which formed a highly overlapping composite response, were then successfully obtained and used to evaluate the progress of ACT interacting with ctDNA. The results of the single-stranded ctDNA and iodide quenching experiments, ctDNA-melting investigations, and viscosity measurements indicated that ACT binds to ctDNA by means of a partial intercalation. Molecular docking studies showed that the specific binding site is mainly located between the ACT and G–C base pairs of ctDNA. This docking prediction was confirmed by use of Fourier-transform infrared (FT-IR) spectral analysis. Results from circular dichroism (CD) spectroscopy revealed that ACT induced a conformational change from the B–ctDNA form to the A–ctDNA form.

Synthesis of boronate-silica hybrid affinity monolith via a one-pot process for specific capture of glycoproteins at neutral conditions

In this study, a boronate-silica hybrid affinity monolith was prepared for specific capture of glycoproteins at neutral pH condition. The monolith was synthesized via a facile one-pot procedure in a stainless steel column by concurrently mixing hydrolyzed alkoxysilanes tetramethoxysilane and vinyltrimethoxysilane, organic monomer 3-acrylamidophenylboronic acid and initiator 2,2′-azobisisobutyronitrile together. The polycondensation of alkoxysilanes and copolymerization of organic monomer and vinyl-silica monolith were carried out successively by reacting at different temperatures. After optimizing the preparation conditions, the resulting hybrid affinity monolith was systematically characterized and exhibited excellent affinity to both cis-diol-containing small molecules and glycoproteins at neutral and physiological pH, including adenosine, horseradish peroxidase, transferrin and ovalbumin. The binding capacity of ovalbumin on monolith was measured to be 2.5 mg g^?1 at pH 7.0. Furthermore, the hybrid affinity monolith was applied to the separation of transferrin from bovine serum sample at a physiological condition. Good repeatability was obtained and the relative standard deviations of retention time were 1.15 and 4.77 % (n?=?5) for run-to-run and column-to-column, respectively.     

Lipid profiling of human plasma from peritoneal dialysis patients using an improved 2D (NP/RP) LC-QToF MS method

An improved online two-dimensional liquid chromatography-quadrupole time-of-flight mass spectrometry (2D LC-QToF MS) system was developed for the lipid profiling of human plasma, in which different lipid classes were separated by the first dimensional normal-phase (NP) LC and different lipid molecular species were separated by the second dimensional reversed-phase (RP) LC. This 2D LC-QToF MS system was built based on a ten-port, two-position valve as the interface, the conditions of which had been optimized and discussed in detail. As two loops were used to trap and transfer the first dimensional elute to the second dimension separately, this new interface suppressed the sample band broadening in the first dimensional column, increased the recovery and repeatability of 2D LC interface, and offered the possibility for the realization of not-stop-flow NP/RP 2D LC system. Finally, 190 endogenous lipid species out of 10 lipid classes were determined within a single run from the plasma of peritoneal patients. This method was also applied to identify the difference in lipid profile between plasma from peritoneal dialysis patients with bad volume status and peritoneal dialysis patients with good volume status. The discovery of 30 potential biomarkers would be helpful to the malnutrition, inflammation, and atherosclerosis syndrome investigation.     

Identification of urinary metabolites of imperatorin with a single run on an LC/Triple TOF system based on multiple mass defect filter data acquisition and multiple data mining techniques

The detection of drug metabolites, especially for minor metabolites, continues to be a challenge because of the complexity of biological samples. Imperatorin (IMP) is an active natural furocoumarin component originating from many traditional Chinese herbal medicines and is expected to be pursued as a new vasorelaxant agent. In the present study, a generic and efficient approach was developed for the in vivo screening and identification of IMP metabolites using liquid chromatography-Triple TOF mass spectrometry. In this approach, a novel on-line data acquisition method mutiple mass defect filter (MMDF) combined with dynamic background subtraction was developed to trace all probable urinary metabolites of IMP. Comparing with the traditionally intensity-dependent data acquisition method, MMDF method could give the information of low-level metabolites masked by background noise and endogenous components. Thus, the minor metabolites in complex biological matrices could be detected. Then, the sensitive and specific multiple data-mining techniques extracted ion chromatography, mass defect filter, product ion filter, and neutral loss filter were used for the discovery of IMP metabolites. Based on the proposed strategy, 44 phase I and 7 phase II metabolites were identified in rat urine after oral administration of IMP. The results indicated that oxidization was the main metabolic pathway and that different oxidized substituent positions had a significant influence on the fragmentation of the metabolites. Two types of characteristic ions at m/z 203 and 219 can be observed in the MS/MS spectra. This is the first study of IMP metabolism in vivo. The interpretation of the MS/MS spectra of these metabolites and the proposed metabolite pathway provide essential data for further pharmacological studies of other linear-type furocoumarins.