Erratum: Synthesis and characterization of diorganotin(IV) complexes of Schiff bases with ONO‐type donors and crystal structure of [N‐(2‐hydroxy‐4‐nitrophenyl)‐3‐ethoxysalicylideneiminato]diphenyltin(IV)

The article referenced above was first published online on 30 August 2007 with incorrect pagination; the pagination has now been corrected online and in print. Copyright © 2007 John Wiley & Sons, Ltd.     

Investigation of chemical activity,SCHIFF base reactions and staining effects of some amino acids by spectrophotometric and theorical methods

In this study, the staining properties of selected amino acids with Brassica oleraceae extract in alum and alum-free media were investigated. Basic, acidic and neutral amino acids (arginine, glutamic acid and glycine) were used to investigate the effect of staining. It was determined that all amino acids were stained in alum media. In the second step, the R group of amino acids found in the proteins of the cell nucleus was reacted with salicyl aldehyde. This reaction was successful only with Arginine. The staining properties of the newly formed compound were also investigated in alum and alum-free environments. Evaluation of the results was done using FT-IR and ¹H NMR methods. All compounds were optimized with the Gaussian G09 program (DFT/B3LYP/6.311 ?G(d.p) basic set. HOMO, LUMO and HOMO-LUMO gap values were determined. Chemical reaction capabilities of amino acids were discussed with the help of HOMO-LUMO gap values.     

New antidepressant drug candidate: Hypericum montbretti extract

This study was designed to investigate possible antidepressant-like effects of the extract prepared from the flowers of Hypericum montbretti Spach. (Guttiferae, Clusiaceae). Phytochemical constituents of the methanolic extract were analysed by HPLC method. The main flavonoid component was detected as rutin, and another highly concentrated phenolic compound was quercitrin. Antidepressant activity of the extract was examined by tail suspension and modified forced swimming tests, whereas the motor coordination of the animals was tested by the Rota-Rod apparatus. Reboxetine at a dose of 20 mg?kg?1 was used as a reference drug. Dose-dependent antidepressant activity was observed in both tests following the administration of extract at 100 and 250 mg?kg?1 doses. To the best of our knowledge, this is the first study reporting the antidepressant activity of H. montbretti extract. Additionally, the results of this work support previous papers reporting the antidepressant activity of rutin.     

Experimental and molecular modeling investigation of (E)-N-{2-[(2-hydroxybenzylidene)amino]phenyl}benzenesulfonamide

The Schiff base compound (E)-N-{2-[(2-hydroxybenzylidene)amino]phenyl}benzenesulfonamide has been synthesized and characterized by IR, NMR and Uv-vis spectroscopies, and single-crystal X-ray diffraction technique. In addition, quantum chemical calculations employing density functional theory (DFT) method with the 6–311++G(d,p) basis set were performed to study the molecular, spectroscopic and some electronic structure properties of the title compound, and the results were compared with the experimental findings. There exists a good correlation between experimental and theoretical data. Enol-imine/keto-amine tautomerization mechanism was investigated in the gas phase and in solution phase using the polarizable continuum model (PCM) approximation. The energetic and thermodynamic parameters of the enol-imine?→?keto-amine transfer process show that the single proton exchange is thermodynamically unfavored both in the gas phase and in solution phase. However, the reverse reaction seems to be feasible with a low barrier height and is supported by negative values in enthalpy and free energy changes both in the gas phase and in solution phase. The solvent effect is found to be sizable with increasing polarity of the solvents for the reverse reaction. The predicted nonlinear optical properties of the compound are found to be much greater than those of urea.     

Complexes formed by the reactions of fluorinated and non-fluorinated organonitriles with [Zn(SO2)2][AsF6]2: A structural study

[Zn(SO₂)₂][AsF₆]₂ (1) has been prepared from zinc metal and AsF₅ in liquid sulfur dioxide, and crystallized from sulfur dioxide giving crystals of [Zn(SO₂)₄(AsF₆)₂] (1a). The compound 1 forms the homoleptic complexes [Zn(NCR)₆](AsF₆)₂ (R: CH₃ (2a), C₆H₅ (3a), C₆F₅ (3b)) with the corresponding nitriles. In these complexes, the metal center is octahedrally surrounded by six ligands (average Zn–N 2.13 ?). Reaction of 1 with the weaker ligand F₃CCN results in dicoordination at the metal center complemented by a two-dimensional polymeric network (2b) containing bridging AsF₆ ⁻ anions. [Zn(SO₂)₄(AsF₆)₂] (1a): monoclinic, P2₁/c, a=8.5176(8) ?, b=13.5787(14) ?, c=14.7661(15) ?, β=99.296(2)°; [Zn(NCCH₃)₆][AsF₆]₂ (2a): rhombohedral, R-3, a=11.2225(8) ?, b=11.2225(8) ?, c=16.9393(14) ?; [Zn (NCCF₃)₂][μ-FAsF₅)₂( (2b): monoclinic, P2₁/c, a=11.226(3) ?, b=6.6147(19) ?, c=10.460(3) ?, β=104.028(5)°; [Zn(NCC₆H₅)₆][AsF₆]₂ (3a): monoclinic, P2₁/n, a=13.7968(10) ?, b=19.8861(15) ?, c=16.1692(12) ?, β=91.563(2)°; [Zn(NCC₆F₅)₆][AsF₆]₂·2SO₂ (3b): monoclinic, P2₁/n, a=10.8448(9) ?, b=154456(13) ?, c=17.5206(15) ?, β=104.158(1)°.     

Structural and spectral studies of N-trans-cinnamylidene-m-toluidine and N-trans-cinnamylidene-m-chloroaniline

N-trans-cinnamylidene-m-toluidine (1) C₁₆H₁₅N, and N-trans-cinnamylidene-m-chloroaniline (2) C₁₅H₁₂NCl form isomorphous crystals which are monoclinic, space group P2_l/c, with unit cell dimensionsa=5.967(2),b=13.793(3),c=15.048(5) Å, =91.97(3)° anda=5.868(2),b=13.788(4),c=15.191(4) Å, =91.87(3)°, respectively. The single-crystal X-ray structure determinations of the title compounds revealtrans structures. Ring (A) C_10–15 and ring (B) C_1–6, are practically planar in both structures with dihedral angels of 61.3(3) and 63.6(2)°, respectively.¹H nmr, u.v. and i.r. spectra are also reported.     

Silver Nanoparticle Thin Films with Nanocavities for Surface‐Enhanced Raman Scattering

The formation of nanometer‐sized gaps between silver nanoparticles is critically important for optimal enhancement in surface‐enhanced Raman scattering (SERS). A simple approach is developed to generate nanometer‐sized cavities in a silver nanoparticle thin film for use as a SERS substrate with extremely high enhancement. In this method, a submicroliter volume of concentrated silver colloidal suspension stabilized with cetyltrimethylammonium bromide (CTAB) is spotted on hydrophobic glass surfaces prepared by the exposure of the glass to dichloromethysilane vapors. The use of a hydrophobic surface helps the formation of a more uniform silver nanoparticle thin film, and CTAB acts as a molecular spacer to keep the silver nanoparticles at a distance. A series of CTAB concentrations is investigated to optimize the interparticle distance and aggregation status. The silver nanoparticle thin films prepared on regular and hydrophobic surfaces are compared. Rhodamine 6G is used as a probe to characterize the thin films as SERS substrates. SERS enhancement without the contribution of the resonance of the thin film prepared on the hydrophobic surface is calculated as 2×10⁷ for rhodamine 6G, which is about one order of magnitude greater than that of the silver nanoparticle aggregates prepared with CTAB on regular glass surfaces and two orders of magnitude greater than that of the silver nanoparticle aggregates prepared without CTAB on regular glass surfaces. A hydrophobic surface and the presence of CTAB have an increased effect on the charge‐transfer component of the SERS enhancement mechanism. The limit of detection for rhodamine 6G is estimated as 1.0×10^?8 M . Scanning electron microscopy and atomic force microscopy are used for the characterization of the prepared substrate.     

Synthesis and characterization of azo-linked Schiff bases and their nickel(II), copper(II), and zinc(II) complexes

Azo compounds were prepared by coupling of benzenediazonium chloride ions with 1-amino-2-hydroxy-4-naphthalene sulfonic acid under alkaline conditions, and Schiff bases, L_1–3 were then obtained by the condensation of 1-amino-2-hydroxy-3-(phenylazo)-4-naphthalene sulfonic acid, 1-amino-2-hydroxy-3-(4-ethylphenylazo)-4-naphthalene sulfonic acid, and 1-amino-2-hydroxy-3-(4-nitrophenylazo)-4-naphthalene sulfonic acid with salicylaldehyde. New copper(II), nickel(II), and zinc(II) complexes of the Schiff base ligands were also prepared and characterized by spectroscopic methods, magnetic measurements, elemental, and thermogravimetric analysis.     

Myrotoxins: a new class of macrocyclic trichothecenes

An isolate of $\text{Myrothecium roridum}$ which is a pathogen on tomatoes in Texas produces a new class of C27 macrocyclic trichothecenes which contains a nonconjugated diene system that includes a vinyl ether group.     

Direct determination of bromide ions in seawater by capillary zone electrophoresis using polyethyleneimine-coated capillaries

A rapid and simple capillary electrophoretic method was developed for the direct determination of bromide ion in seawater. We have found an effective method, based on the use of polyethyleneimine-coated capillaries and the addition of sodium chloride to the background electrolyte. The use of coated capillaries with a cationic polymer changes the direction of the electroosmotic flow in the capillary, which favors the migration speed of the bromide ion and enables the use of low salt concentrations in the separation electrolyte. Bromide ion in seawater can be determined within 2 min using this system and 20 mmol L^-1 NaCl-containing separation electrolyte. The detection limit for the bromide ion was 0.45 g ml^-1. The method was applied to the determination of bromide ion in seawater samples collected from the Bosphorus and the Black Sea. Bromide contents in samples from 0 to 72 m depths varied between 33.2 and 72.8 mg L^-1 with a mean 3.0% RSD.