Validation of SPE‐HPLC determination of 1,4‐benzodiazepines and metabolites in blood plasma,urine, and saliva

A simple, sensitive, selective, and reproducible RP‐HPLC method with DAD detection at 240 nm was developed for the determination of six 1,4‐benzodiazepines: bromazepam (BRZ), clonazepam (CLZ), diazepam (DZP), flunitrazepam (FNZ), lorazepam (LRZ), alprazolam (APZ); and two metabolites: α‐hydroxyalprazolam (HALZ) and α‐hydroxytriazolam (HTZL) in human plasma, urine, and saliva, using colchicine as internal standard, after SPE using Nexus Varian cartridges. Separation was performed on a Kromasil C₈ (250 mm×5 mm, 5 μm) analytical column with a gradient mobile phase containing methanol, ACN and 0.05 M ammonium acetate. Linearity was held within the range 0.3–20.0 ng/μL, with coefficients of determination (r²) better than 0.997. The within‐ and between‐day assay RSD at 2, 4, 8 ng/μL ranged from 0.03 to 4.7% and 0.5 to 7.0%, respectively in standards, from 1.3 to 7.9% and 3.3 to 7.3%, respectively in plasma, from 2.1 to 6.0% and 2.1 to 7.8%, respectively in urine and at 0.5, 1.0, 2.0 ng/μL ranged from 2.22 to 5.8% and 2.2 to 8.1%, respectively, in saliva. The mean relative recoveries were 96.3–108.6, 96.0–108.2, 94.3–107.1, 97.0–107.0% in within‐day assay and 96.8–107.7, 94.6–107.6, 93.2–105.8, 96.0–108.6 in between‐day assay for standard, plasma, urine, and saliva, respectively. The LOD and LOQ were 0.02–0.47 and 0.07–1.57 ng/μL, respectively.     

Do The Twist: Efficient Heavy-Atom-Free Visible Light Polymerization Facilitated by Spin-Orbit Charge Transfer Inter-system Crossing

The use of visible light to drive polymerizations with spatiotemporal control offers a mild alternative to contemporary UV-light-based production of soft materials. In this spectral region, photoredox catalysis represents the most efficient polymerization method, yet it relies on the use of heavy-atoms, such as precious metals or toxic halogens. Herein, spin-orbit charge transfer intersystem crossing from boron dipyrromethene (BODIPY) dyads bearing twisted aromatic groups is shown to enable efficient visible light polymerizations in the absence of heavy-atoms. A ≈5–15× increase in polymerization rate and improved photostability was achieved for twisted BODIPYs relative to controls. Furthermore, monomer polarity had a distinct effect on polymerization rate, which was attributed to charge transfer stabilization based on ultrafast transient absorption and phosphorescence spectroscopies. Finally, rapid and high-resolution 3D printing with a green LED was demonstrated using the present photosystem.     

Synthesis,In Vitro α-Amylase Activity,and Molecular Docking Study of New Benzimidazole Derivatives

Russian Journal of Organic Chemistry - New benzimidazole derivatives were synthesized by reacting substituted phenacyl bromides with 1H-benzimidazole-2-thiols. The synthesized compounds were...     

A computational mechanistic study of the deamination reaction of melamine

A detailed computational study of the deamination reaction of melamine by OH^–, n H₂O/OH^–, n H₂O (where n = 1, 2, 3), and protonated melamine with H₂O, has been carried out using density functional theory and ab initio calculations. All structures were optimized at M06/6‐31G(d) level of theory, as well as with the B3LYP functional with each of the basis sets: 6‐31G(d), 6‐31 + G(d), 6‐31G(2df,p), and 6‐311++G(3df,3pd). B3LYP, M06, and ω B97XD calculations with 6‐31 + G(d,p) have also been performed. All structures were optimized at B3LYP/6‐31 + G(d,p) level of theory for deamination simulations in an aqueous medium, using both the polarizable continuum solvation model and the solvation model based on solute electron density. Composite method calculations have been conducted at G4MP2 and CBS‐QB3. Fifteen different mechanistic pathways were explored. Most pathways consisted of two key steps: formation of a tetrahedral intermediate and in the final step, an intermediate that dissociates to products via a 1,3‐proton shift. The lowest overall activation energy, 111 kJ mol^?1 at G4MP2, was obtained for the deamination of melamine with 3H₂O/OH^?.     

Room temperature ferroelectric effect and enhanced dielectric permittivity in Rochelle salt/PVA percolative composite films

Rochelle salt (RS) filled polyvinyl alcohol (PVA) composite films have been prepared via a simple solution casting technique. The transport, dielectric and ferroelectric properties of the samples have been studied. The dielectric permittivity decreases slowly with increasing frequency and rise gradually with increasing temperature and RS contents in the composites. As the volume fraction of the RS reaches to percolation threshold (f_c ～0.0538), an abrupt increase in the dielectric permittivity (～403 almost 80 times higher compared to pure PVA with low loss ～0.18 at 1 kHz and room temperature) occurs in the RS/PVA composite film, which is attributed to the formation of the conductive network in the matrix. Ferroelectric loops up to room temperature (300 K) and the slight increase in Curie temperature from 297 to 300 K have also been observed for percolative composite film. The developed composite material with low loss high dielectric permittivity and room temperature ferroelectric behaviors might be applied in the technological fields.     

Warped product CR-submanifolds of cosymplectic manifolds

In the present paper, we study warped product CR-submanifolds of cosymplectic manifolds. It is shown that the warped product of the type ${N_\perp\times{_f}N_T}$ is trivial and obtain a characterization result for the warped product of the type ${N_T\times{_f}N_\perp}$ , where N _T and ${N_\perp}$ are invariant and anti-invariant submanifolds of a cosymplectic manifold ${\bar M}$ , respectively.     

Four new polyoxygenated gorgosterols from the gorgonian Isis hippuris

Four new polyoxygenated steroids (1-4) together with four known ones (5-8) have been isolated from the gorgonian Isis hippuris. The structures of the new compounds have been elucidated by spectroscopic analysis and chemical conversion. All of the new steroids showed moderate cytotoxicity against cultured NBT-T2 cells.     

A new eudesmane sesquiterpene from Pluchea arguta

A new eudesmane sesquiterpene, pluchargen A (3-beta-[3'-chloro-2'-hydroxy-2'-methyl butyroyl]-cuauhtemone), was isolated from the whole plant of Pluchea arguta, and the structure was elucidated on the basis of 1- and 2-D NMR spectroscopic studies.