HClO4‐SiO2: An Efficient and Useful Catalyst for the Synthesis of 3‐Aryl‐2H‐benzo[1,4]oxazine

HClO₄‐SiO₂, efficiently catalyzed the condensation of o‐aminophenols and 2‐bromo‐1‐aryl‐ethanones to yield 3‐aryl‐2H‐benzo[1,4]oxazines in good yields.     

A quantitative study of sodium tungstate protective effect on pancreatic beta cells in streptozotocin-induced diabetic rats

Diabetes is a major public health problem. Development of new therapies that are able to improve glycemia management, cure diabetes, and can even protect from it, are of great interest. This study investigated the protective effect of sodium tungstate against STZ-induced beta-cell damages by means of stereological methods. Sixty rats were divided into six groups: control (C), tungstate-treated control (TC), STZ-induced diabetic (D), STZ-induced diabetic rats were treated by sodium tungstate from 1 week before STZ injection (TDB), food-restricted diabetic (FRD), and diabetic rats treated with sodium tungstate 1 week after STZ administration (TDA). Stereological estimation of pancreas volume, islets volume density, volume-weighted mean islets volume and mass of beta cells, islets, and pancreas and total number of islets were done. Islets volume density, volume-weighted mean islets volume, and mass of beta cells, islets, and pancreas of TDB group was significantly higher than D, FRD and TDA groups (P < 0.001) and was comparable to controls (C and TC groups). Total number of islets, pancreas wet weight and volume did not show any significant changes between these groups (P > 0.05).Results suggested that sodium tungstate preserves pancreatic beta cells from STZ-induced damages and diabetes induction in rats.     

A Novel Fluorescence Nanobiosensor based on Modified Graphene Quantum dots-HTAB for Early Detection of Fetal Sexuality with Cell Free Fetal DNA

Journal of Fluorescence - Recently, prenatal diagnosis with non-invasive insight is a progressive approach in clinical medicine to prevent the birth of infants with genetic abnormalities. Cell free...     

Three-Component Synthesis of Dialkyl 2-(Alkylimino-Methylene)3- (2,2,5-Trimethyl-4,6-Dioxo-1,3-Dioxan-5-Yl)-Succinates

The adduct produced in the reaction between alkyl isocyanides and dialkyl acetylenedicarboxylates was trapped by 2,2,5-trimethyl-1,3-dioxane-4,6-dione (methyl Meldrum's acid), to afford highly functionalized ketenimines in good yields.     

New zinc(II), copper(II), nickel(II), and vanadium(IV) complexes containing disulfide ligand: Synthesis,spectroscopic studies and calf thymus DNA interaction investigation

New Schiff base complexes of zinc(II), copper(II), nickel(II), and vanadium(IV) were synthesized using the Schiff base ligand formed by the condensation of 2-aminoethanethiol and 2-hydroxy-1-naphthaldehyde. The tetradentate Schiff base ligand N,N´-(3,4-dithiahexane-1,6-diyl)bis(2-hydroxy-1-naphthaleneimine), containing a disulfide bond, was coordinated to the metal(II) ions through the two azomethine nitrogen atoms and two deprotonated phenolic oxygens of two different ligands which was connected to each other by sulfur-sulfur bond. The molar conductivity values of complexes in DMSO solvent implied the presence of nonelectrolyte species. The fluorescence properties of the Schiff base ligand and its complexes were studied in dimethylsulfoxide. The Schiff base ligand and its complexes were characterized by FT-IR, ¹H NMR, UV/Vis spectroscopies, elemental analysis, and conductometry. The crystal structure of tetradentate Schiff base ligand was characterized by single crystal X-ray diffraction. The Schiff base ligand was contained disulfide bond. Furthermore, the binding interaction of these complexes with calf thymus DNA (CT-DNA) was investigated by different methods.     

Aryl, methyl-diplatinum complexes each with a metal-metal donor-acceptor bond and bridging 2-diphenylphosphinopyridine (PN) ligands: general synthetic approach and mechanism of isomerization

A general synthetic method has been designed to prepare a series of unsymmetrical cationic organo-diplatinum complexes each containing two bridging 2-diphenylphosphinopyridine (PN), PPh(2)py, ligands and a platinum-platinum donor-acceptor bond. Thus, reaction of cis-[PtR(2)(SMe(2))2] (R = Ph, p-MeC(6)H(4) or p-FC(6)H(4)), 1, or cis,cis-[R(2)Pt(micro-SMe(2))(2)PtR(2)](R = Me) with 2 equiv. or 4 equiv., respectively, of PN in CH(2)Cl(2) gave cis-[PtR(2)(PN-kappa(1)P)(2)], 2. When complex 2 was reacted with 1 equiv. of HX (X = CF(3)COO) in CH(2)Cl(2), an approximately 2 : 1 mixture of trans-[PtRX(PN-kappa(1)P)(2)], 3, and [PtR(eta(2)-PN)(PN-kappa(1)P)]X, 4, was obtained. The reaction of one equiv. of the latter monomeric mixture with 0.5 equiv. of cis,cis-[R'(2)Pt(micro-SMe(2))(2)PtR'(2)] (R' = Me) or one equiv. of cis-[PtR'(2)(SMe(2))(2)] (R' = p-MeC(6)H(4)) in CH(2)Cl(2) immediately gave the head-to-head (HH) stereoisomer of the diplatinum complex hh-[RPt(micro-PN)(2)PtR'(2)]X, 6. However, the same reaction in benzene gave the corresponding head-to-tail (HT) stereoisomer ht-[RPt(micro-PN)(micro-NP)PtR'(2)]X, 9, in pure form after a few hours. The conversion of the HH isomer 6 to the HT isomer 9 in CH(2)Cl(2) took place very slowly during 10 d, while the conversion in C(6)H(6) was much faster and took place over 5 h. Based on the observations, a mechanism for the conversion of the kinetic HH stereoisomer to the thermodynamic HT stereoisomer is suggested which involves association of X- with the N(2)PtR'(2) center following by one-arm dissociation of one of the PN bridging ligands from the nitrogen terminal in the HH isomer, and subsequent exchange of the ligating atom and reformation of the HT arrangement. The methyl-di p-tolyl dimer ht-[MePt(micro-PN)(micro-NP)Pt(p-MeC(6)H(4))(2)]X, 9e, in solution gradually isomerizes to ht-[(p-MeC(6)H(4))Pt(micro-PN)(micro-NP)PtMe(p-MeC(6)H(4))]X, 11, by an aryl ligand transfer. All the complexes were fully characterized using multinuclear (1H, 31P and 195Pt) NMR spectroscopy and the complexes ht-[PhPt(micro-PN)(micro-NP)PtMe(2)]X, 9a, and ht-[(p-MeC(6)H(4))Pt(micro-PN)(micro-NP)PtMe(p-MeC(6)H(4))]X, 11, were further characterized by single crystal X-ray crystallography.