Fate, distribution, and bioconcentration of pesticides impact on the organic farms of Cameron Highlands, Malaysia.

Occurrence and distribution of organochlorine pesticides (OCPs), organophosphate pesticides (OPPs), and pyrethroid pesticides (PYRs) residues in the leafy vegetables were analyzed together with the soil samples using gas chromatography-electron capture detector. Edible tissues of vegetables showed detectable residues of these compounds indicating the influence of the conventional farms and nearby organic farms. In the vegetables, the OCPs concentrations were recorded as nd-133.3 ng/g, OPPs as nd-200 ng/g, and PYRs as nd-33.3 ng/g. In the soil, the OCPs concentrations were recorded as nd-30.6 ng/g, OPPs as nd-26.6 ng/g, and for PYRs as nd-6.7 ng/g. Bioconcentration factor (BCF) was higher for the OPPs (0.3) than the OCPs and PYRs (1.1). The OCPs concentration in the vegetables decreased in the following order: spinach > celery > broccoli > cauliflower > cabbage > lettuce > mustard. For OPPs, the concentration decreased in the following order: cauliflower > spinach > celery > cabbage > broccoli > lettuce > mustard and for PYRs as spinach > celery > lettuce > cabbage > broccoli. Principal component analysis indicates that the sources of these pesticides are not the same, and the pesticide application on the vegetables depends on the type of crop. There is a significant positive correlation between OPPs and the soil (r = 0.65) as compared to OCPs and PYRs (r = 0.1) as the vegetables accumulated OPPs more efficiently than OCPs and PYRs.

Determination of pesticide residues in leafy vegetables at parts per billion levels by a chemometric study using GC-ECD in Cameron Highlands, Malaysia.

A simple and sensitive analytical method has been developed employing gas chromatography coupled with electron capture detector (GC-ECD), and validated for screening and quantification of 15 pesticide residues at trace levels in cabbage, broccoli, cauliflower, lettuce, celery, spinach, and mustard. The method consists of two steps, first, to determine the significance of each factor by Pareto chart followed by optimization of these significant factors using central composite design (CCD). Minitab statistical software was used for these multivariate experiments for the generation of 24-1 design and CCD matrices. The method evaluation was done by external standard calibration with linearity range between 0.5 and 3mg/kg, with correlation coefficient 0.99, limit of detection (LOD) ranges between 0.02 and 4.5ng/g, and limit of quantification (LOQ) ranges between 0.2 and 45ng/g. The average recovery was between 60% and 128%, with RSD 0.2-19.8%. The method was applied on real vegetable samples from Cameron Highlands.

Diorganotin(IV) derivatives of N-methyl p-fluorobenzo-hydroxamic acid: preparation, spectral characterization, X-ray diffraction studies and antitumor activity.

Three diorganotin(IV) complexes of the general formula R2Sn[RcC(O)N(RN)O] (Rc = aryl, RN = Alkyl) have been synthesized by refluxing in toluene the corresponding diorganotin(IV) oxides with the free ligand N-methyl p-fluorobenzohydroxamic acid, using a Dean and Stark water separator. The ligand was derived from the reaction of the corresponding p-fluorobenzoyl chloride and N-methylhydroxylamine hydrochloride in the presence of sodium hydrogen carbonate. The isolated free ligand and its respective diorganotin compounds have been characterized by elemental analysis, IR and 1H-, 13C-, 119Sn-NMR spectroscopies. The crystal structures of the diorganotin complexes have been confirmed by single crystal X-ray diffraction methods. The investigations carried out on the diorganotin(IV) complexes of N-methyl p-fluorobenzohydroxamic acid confirmed a 1:2 stoichiometry. The complex formation took place through the O,O-coordination via the carbonyl oxygen and subsequent deprotonated hydroxyl group to the tin atom. The crystal structures of three diorganotin complexes were determined and were found to adopt six coordination geometries at the tin centre with coordination to two ligand moieties.

(E)-2-[1-(1-Benzothio-phen-2-yl)ethyl-idene]-N-phenyl-hydrazinecarboxamide.

The title compound, C(17)H(15)N(3)OS, crystallizes with two unique mol-ecules, denoted 1 and 2, in the asymmetric unit. The two mol-ecules are closely similar and overlay with an r.m.s. deviation of 0.053 Å. Both mol-ecules adopt E configurations with respect to the C=N bonds. The dihedral angles between the benzothio-phene groups and N-bound phenyl rings are 36.36 (9)° for mol-ecule 1 and 29.71 (9)° for mol-ecule 2. The C=N-NH-C(O)NH ethyl-idene-hydrazinecarboxamide units are also reasonably planar, with r.m.s. deviations of 0.061 and 0.056 Å, respectively, for the two mol-ecules. The methyl substituents lie 0.338 (3) and 0.396 (3) Å, respectively, from these planes. The C=N-NH-C(O)NH planes are inclined to the phenyl rings at 13.65 (11) and 15.56 (11)°, respectively, in mol-ecules 1 and 2. This conformation is enhanced by weak intra-molecular C-H⋯O hydrogen bonds between ortho-H atoms of the two phenyl rings and the carbonyl O atoms, which generate S(6) rings in each mol-ecule. In the crystal, pairs of mol-ecules are linked by pairs of inter-molecular N-H⋯O hydrogen bonds into dimers. Alternating dimers are further inter-connected by weak C-H⋯O contacts into zigzag rows along b. The rows are stacked along a by C-H⋯π contacts involving the benzene ring from molecule 2 and the thiophene ring from molecule 1 of adjacent benzothio-phene units.

3-[(E)-(4-Chloro-benzyl-idene)amino]-1-phenyl-thio-urea.

In the title compound, C(14)H(12)ClN(3)S, the dihedral angle between the terminal benzene rings is 56.6 (2)°; the benzene rings lie to the same side of the mol-ecule. The major twist in the mol-ecule occurs around the C(ar)-N bond (ar is aromatic) [C-N-C-C = 49.9 (5)°]. The configuration about the N=C bond [1.271 (4) Å] is E. The amine H atoms lie on opposite sides of the mol-ecule with one forming an intra-molecular N-H⋯N(imine) hydrogen bond and an S(5) ring. In the crystal, centrosymmetric dimers are formed via {⋯HNC=S}(2) synthons.

3-(2-Hy-droxy-phen-yl)-1-{(E)-[1-(pyrazin-2-yl)ethyl-idene]amino}-thio-urea monohydrate.

In the title compound, C(13)H(13)N(5)OS·H(2)O, the thio-urea mol-ecules closely resemble each other and are approximately planar; the dihedral angles formed between the terminal benzene rings are 7.88 (8) and 7.20 (8)°, respectively. The observed planarity correlates with the presence of bifurcated N-H⋯(O,N) hydrogen bonds. In the crystal, the mol-ecules are connected into supra-molecular double chains via a combination of N-H⋯S (linking the two independent mol-ecules), O-H⋯O and O-H⋯N (linking dimeric aggregates into a supra-molecular chain via hy-droxy-water, water-water and water-pyrazine inter-actions) and O-H⋯S hydrogen bonds (connecting two chains). The chains are further connected by C-H⋯N and C-H⋯S inter-actions.

n-Butyl-dichlorido{4-cyclo-hexyl-1-[phenyl(2-pyridyl-κN)methyl-ene]-thiosemicarbazidato-κN,S}tin(IV) chloro-form monosolvate.

The monodeprotonated Schiff base ligand in the title com-pound, [Sn(C(4)H(9))(C(19)H(21)N(4)S)Cl(2)]·CHCl(3), N,N',S-chelates to the Sn atom, which is six-coordinated in an octa-hedral environment. The three coordinating atoms along with the butyl C atom comprise a square plane, above and below which are positioned the Cl atoms. The amino group is a hydrogen-bond donor to a Cl atom of an adjacent mol-ecule, the hydrogen bond giving rise to a helical chain propagating in [010]. The Cl and H atoms of the chloro-form mol-ecule are disordered over two positions in an 0.67:0.33 ratio.

Bis(N-butyl-N-ethyl-dithio-carbamato-κS,S')nickel(II).

The dithio-carbamate anions in the title compound, [Ni(C(7)H(14)NS(2))(2)], chelate to the Ni(II) atom, which is four-coordinate in a square-planar geometry. The Ni(II) atom lies on a center of inversion.

Bis(N-isopropyl-N-methyl-dithio-carbamato-κS,S')diphenyl-tin(IV).

The dithio-carbamate anions in the title compound, [Sn(C(6)H(5))(2)(C(5)H(10)NS(2))(2)], chelate to the Sn(IV) atom, which is six-coordinated in a skew-trapezoidal-bipyramidal geometry. The mol-ecule lies across a twofold rotation axis.

(E)-3,4-Dihydroxy-benzaldehyde 4-ethyl-thio-semicarbazone.

The title compound, C(10)H(13)N(3)O(2)S, was prepared by condensation of 3,4-dihydroxy-benzaldehyde with 4-ethyl-3-thio-semicarbazide. The mol-ecule adopts an E configuration with respect to the C=N bond. One of the OH substituents on the dihydroxy-benzene ring is disordered over the two possible 3-positions on either side of the ordered 4-hydr-oxy group. The occupancy of the major disorder component refined to 0.633 (7). The mol-ecule is essentially planar, with an r.m.s. deviation through all non-H atoms of 0.0862 Å. An intra-molecular N-H⋯N hydrogen bond forms between the outer amine residue and the imine N atom, generating an S(5) ring motif and contributing to the planarity of the mol-ecule. In the crystal structure, an extensive network of classical O-H⋯O, O-H⋯S and N-H⋯S hydrogen bonds and weak C-H⋯O and S⋯O [3.301 (3) Å] inter-actions link mol-ecules into sheets running approximately parallel to the ab plane.

(E)-2-[1-(1-Benzothio-phen-3-yl)ethyl-idene]hydrazinecarbothio-amide methanol hemisolvate.

The asymmetric unit of the title compound, C(11)H(11)N(3)S(2)·0.5CH(4)O, contains four thio-semicarbazone mol-ecules and two methanol solvent mol-ecules. Each hydrazinecarbothio-amide mol-ecule adopts an E configuration with respect to the C=N double bond and is stabilized by an intra-molecular N-H⋯N hydrogen bond, resulting in an S(5) ring motif. In the crystal structure, an extensive network of N-H⋯O, N-H⋯N, O-H⋯S and N-H⋯S hydrogen bonds and weak C-H⋯O, C-H⋯N and C-H⋯S contacts together with an S⋯S [3.5958 (14) Å] and a C-H⋯π inter-action form a three-dimensional network.

3,4-Dihydroxy-benzaldehyde 4-phenyl-thio-semicarbazone.

Mol-ecules of the title compound, C(14)H(13)N(3)O(2)S, are linked by inter-molecular O-H⋯O hydrogen bonds into centrosymmetric dimers forming R(2) (2)(4) rings which are further linked by O-H⋯S hydrogen bonds and weaker N-H⋯S and N-H⋯O hydrogen bonds to form a three-dimensional network.

3,4-Dihydroxy-benzaldehyde thio-semi-carbazone.

The asymmetric unit of the title compound, C(8)H(9)N(3)O(2)S, contains three independent mol-ecules which are stacked approximately over each other. In the crystal structure, centrosymmetric pairs of mol-ecules are formed through inter-molecular hydr-oxy-hydr-oxy O-H⋯O and hydr-oxy-sulfur O-H⋯S hydrogen bonds which are, in turn, linked into a two-dimensional network by N-H⋯O(hydr-oxy) hydrogen bonds.

(E)-3,4-Dihydroxy-benzaldehyde 4-methyl-thio-semicarbazone.

The title compound, C(9)H(11)N(3)O(2)S, adopts an E configuration with respect to the C=N bond. The mol-ecule is approximately planar, with an r.m.s. deviation from the mean plane through all 15 non-H atoms of 0.152 Å; the dihedral angle between the benzene ring plane and the least-squares plane through the thio-semicarbazone unit is 12.48 (7)°. A weak intra-molecular N-H⋯N inter-action contributes to the planarity of the semicarbazone unit. Centrosymmetric pairs of O-H⋯O and N-H⋯S hydrogen bonds form chains along c, generating R(2) (2)(10) and R(2) (2)(8) ring motifs, respectively. In the crystal structure, these chains are further linked by inter-molecular O-H⋯S and C-H⋯O inter-actions, forming stacks down the c axis.

1-Benzothio-phene-2-carbaldehyde 4-ethyl-thio-semicarbazone.

The title compound, C(13)H(15)N(3)S(2), crystallizes with two unique mol-ecules, A and B, in the asymmetric unit. These differ principally in that the methyl group of the 4-ethyl-thio-semicarbazone moiety is ordered in mol-ecule A but disordered over two positions with equal occupancies in mol-ecule B. The benzothio-phene group and the semicarbazone unit are inclined at dihedral angles of 11.78 (8)° for mol-ecule A and 8.18 (13)° for mol-ecule B. Weak intra-molecular N-H⋯N inter-actions contribute to the planarity of the semicarbazone units in both mol-ecules and each mol-ecule adopts an E configuration with respect to the C=N bonds. In the crystal structure, mol-ecules form centrosymmetric dimers as a result of N-H⋯S hydrogen bonds, augmented by C-H⋯S inter-actions for mol-ecule A and C-H⋯S inter-actions for mol-ecule B. Weak C-H⋯π inter-actions stack the dimers of both mol-ecules into columns down the a axis.

3-Meth-oxy-N-p-tolyl-benzohydroxamic acid.

Two mol-ecules of the title compound, C(15)H(15)NO(3), are linked by a pair of O-H⋯O(carbon-yl) hydrogen bonds over a centre of inversion to form a hydrogen-bonded dimer. With respect to the -C(=O)-N(OH)- unit, the methoxy-substituted ring is twisted by 42.2 (1)°, whereas the methyl-substituted ring is twisted by 52.2 (1)°.