Abdussalam Salhin

Hydrazone-based ligands for micro-solid phase extraction-high performance liquid chromatographic determination of biogenic amines in orange juice.

Eight hydrazone-based ligands were synthesized, trapped in a silica sol-gel matrix, and were subsequently used in the micro-solid phase extraction (μ-SPE) of biogenic amines (BAs). The BAs investigated were tryptamine, phenylethylamine, putrescine, histamine, tyramine and spermidine. Prior to the extraction, dansyl chloride was added to the samples which were heated to 70°C for 10 min. The samples were extracted with μ-SPE, after which analytes were desorbed using acetonitrile via ultrasonication. The extracts were analysed by high performance liquid chromatography (HPLC) with ultraviolet detection. Of the eight ligands investigated as sorbents, benzophenone 2,4-dinitrophenylhydrazone was found to be the most promising. The enhanced π-π interaction between the analytes and the ligand facilitated the adsorption process. Under the most suitable extraction conditions, the method demonstrated good linearity with correlation coefficient of more than 0.985 over a concentration range of 1-50 μg L(-1). Satisfactory repeatability with relative standard deviations of 7.43-11.30% (n=3) were obtained. Detection limits ranged from 3.8 to 31.3 ng L(-1). The μ-SPE method exhibited lower recoveries (71.5-87.4%) when compared to the solid phase extraction technique (79.7-95.0%), but enrichment factors of 94-460 were obtained. The proposed μ-SPE-HPLC method was applied to the determination of BAs in orange juice purchased from local supermarkets, with satisfactory results. The orange juices were characterized by the presence of relatively high levels of putrescine (range, 550-2210 μg L(-1)) but tryptamine and phenylethylamine were not detected in any of the tested samples.

Synthesis of isatin thiosemicarbazones derivatives: in vitro anti-cancer, DNA binding and cleavage activities.

New derivatives of thiosemicarbazone Schiff base with isatin moiety were synthesized L1-L6. The structures of these compounds were characterized based on the spectroscopic techniques. Compound L6 was further characterized by XRD single crystal. The interaction of these compounds with calf thymus (CT-DNA) exhibited high intrinsic binding constant (k(b)=5.03-33.00×10(5) M(-1)) for L1-L3 and L5 and (6.14-9.47×10(4) M(-1)) for L4 and L6 which reflect intercalative activity of these compounds toward CT-DNA. This result was also confirmed by the viscosity data. The electrophoresis studies reveal the higher cleavage activity of L1-L3 than L4-L6. The in vitro anti-proliferative activity of these compounds against human colon cancer cell line (HCT 116) revealed that the synthesized compounds (L3, L6 and L2) exhibited good anticancer potency.

(E)-4-Hydroxy-N′-(3-hydroxy-4-methoxybenzylidene)benzohydrazide

The molecule of the title benzohydrazide derivative, C15H14N2O4, exists in a trans conformation with respect to the C=N double bond and is twisted, the dihedral angle between the two benzene rings being 24.17 (6)°. The methoxy group is almost co-planar with respect to the attached benzene ring [Cm—O—C—C (m = methyl) = −1.45 (17)°]. In the crystal, the molecules are linked by N—H⋯O and O—H⋯O hydrogen bonds into sheets parallel to the bc plane. These sheets are further connected into a three-dimensional network by weak C—H⋯O and C—H⋯π interactions.

A STRUCTURAL STUDY OF THE INTERACTION OF DIBENZYLDIAZA-18-CROWN-6 WITH NEODYMIUM(III) NITRATE HEXAHYDRATE

Abstract The structure of the complex salt, [C26H40N2O4][Nd(NO3)5(H2O)] (1), was determined by single crystal X-ray diffraction. It consists of alternating layers of the anionic complex, [Nd(NO3)5(H2O)]2−, and the cationic diprotonated [2H.azacrown]2+. The Nd3+ complex anion is coordinated to five bidentate nitrate ligands and a water ligand to give an 11-coordinated environment. Each Nd moiety is linked to another through intermolecular hydrogen bonding to form pairs of Nd moieties. The azacrown adopts a chair conformation and the benzyl groups are attached to the nitrogen atoms in an anti position with respect to each other, above and below the plane of the macro-ring in agreement with the conformation of the uncomplexed protonated azacrown as obtained by the PM3 method.

(E)-4-Hy-droxy-N'-(4-hy-droxy-3-meth-oxy-benzyl-idene)benzohydrazide.

In the title compound, C15H14N2O4, the N=C double bond has an E configuration. The two benzene rings make a dihedral angle of 28.59 (6)°. In the crystal, molecules are linked into a three-dimensional network by intermolecular N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds and stabilized by weak C—H⋯π interactions.

A structural study of (dibenzyldiaza-18-crown-6) lanthanum(III) thiocyanate

Abstract The structure of the complex La(NCS) 3 C 26 H 38 N 2 O 4 ( 1 ) was determined by single-crystal X-ray diffraction and the structure of the coordinating ligand, C 26 H 38 N 2 O 4 ( 2 ), was studied by the semi-empirical PM3 method. The bonding around La consists of a primary coordination of three thiocyanate N atoms and a secondary coordination of two N atoms and four O atoms of the macrocycle. The primary coordination about La gives an almost planar trigonal configuration that bisects the plane of the macrocycle with La lying in the centre of the macrocycle cavity. The benzyl groups that are attached to the macrocycle are in syn conformation with respect to the macrocycle plane with one of the La–NCS bonds pointing above the plane and the other two La–NCS bonds pointing below the plane in the direction of the benzyl groups. The PM3 calculation shows that the optimised diazacrown has an open structure of a pseudo D 2d symmetry with the two benzyl side-arms positioned away from the cavity.

Flow Injection Analysis of Mercury Using 4-(Dimethylamino) Benzaldehyde-4-Ethylthiosemicarbazone as the Ionophore of a Coated Wire Electrode

A flow injection analysis (FIA) incorporating a thiosemicarbazone-based coated wire electrode (CWE) was developed method for the determination of mercury(II). A 0.1 M KNO3 carrier stream with pH between 1 and 5 and flow rate of 1 mL·min−1 were used as optimum parameters. A linear plot within the concentration range of 5 × 10−6–0.1 M Hg(II), slope of 27.8 ± 1 mV per decade and correlation coefficient (R2) of 0.984 were obtained. The system was successfully applied for the determination of mercury(II) in dental amalgam solutions and spiked environmental water samples. Highly reproducible measurements with relative standard deviation (RSD < 1% (n = 3)) were obtained, giving a typical throughput of 30 samples·h−1.

Determination of lanthanum in monazite sand after selective solvent extraction separation of the picrate with dibenzo-[24]-crown-8

The solvent extraction of LaIII from picrate media was carried out with a dichloromethane solution containing large cavity size crown ethers (> 4A), namely dibenzo-[24]-crown-8 (DB24C8), dicyclohexano-[24]-crown-8 (DCH24C8) and dibenzo-[30]-crown-10 (DB30C10). It was found that LaIII was poorly extracted when DB30C10 was used, whereas both DB24C8 and DCH24C8 were good extractants. However, DB24C8 was preferred over DCH24C8 owing to its superior selectivity over the other lanthanides. The effects of variables such as solvent, counter ion concentration, pH, ligand concentration, equilibration time, stripping agent and selectivity over other elements were investigated. Under the optimized conditions, LaIII was quantitatively extracted from 0.0002 mol l–1 picric acid at pH 9 with 0.02 mol l–1 DB24C8 in dichloromethane. The extracted metal ion was stripped from the organic phase with 0.5 mol l–1 perchloric acid, and its concentration determined spectrophotometrically at 651.5 nm as its complex with Arsenazo III (pH, 3.2). A significant selectivity for LaIII over other lanthanides was observed. Replicate analysis of a monazite sand sample for lanthanum yielded results comparable to those obtained by atomic absorption spectrometry. The composition of the extracted species, viz., LaIII: DB24C8: picrate, was 1:1:3.

(Z)-N-Methyl-2-(5-nitro-2-oxoindolin-3-yl­idene)hydrazinecarbothio­amide

In the title compound, C10H9N5O3S, an intramolecular N—H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, molecules are linked via N—H⋯S hydrogen bonds into a zigzag chain along the b axis. C—H⋯O interactions are observed between the chains.

(Z)-2-(5-Chloro-2-oxoindolin-3-yl­idene)-N-phenyl­hydrazinecarbothio­amide

In the title compound, C15H11ClN4OS, the dihedral angle between the nine-membered 5-chloroindolin-2-one ring system and the benzene ring is 10.00 (6)°. Intramolecular cyclic N—H⋯O and C—H⋯S hydrogen-bonding interactions [graph set S(6)] are present in the N—N—C—N chain between the ring systems. In the crystal, molecules form centrosymmetric cyclic dimers through intermolecular N—H⋯O hydrogen bonds [graph-set R 2 2(8)] and are extended by C—H⋯Cl interactions into infinite chains which propagate along [100].