Octyl (2E)-2-[2-(di-phenyl-phosphan-yl)benzyl-idene]hydrazinecarbodi-thio-ate.

The title compound, C28H33N2S2P, adopts the thione tautomeric form, as supported by the C-S distance [1.6744 (18) Å]. The Schiff base exhibits an E conformation about the C=N bond but a Z conformation about the C-N bond. The terminal chain is disordered over two sets of sites with an occupancy ratio of 0.732 (3):0.268 (3). In the crystal, pairs of N-N-H hydrogen bonds between the thione groups link neighbouring mol-ecules into centrosymmetric dimers.

The trivalent copper complex of a conjugated bis-dithiocarbazate Schiff base: stabilization of Cu in three different oxidation states.

The new tribasic N(2)S(2) ligand H(3)ttfasbz has been synthesized by condensation of 4-thenoyl 2,2,2-trifluoroacetone and S-benzyl dithiocarbazate. On complexation with copper(II) acetate, spontaneous oxidation to the Cu(III) oxidation state is observed, and the complex [Cu(ttfasbz)] has been isolated and characterized structurally. Reduction to the EPR active Cu(II) analogue has been achieved chemically and also electrochemically, and in both cases, the process is totally reversible. The Cu(III/II) redox potential of the complex is remarkably low and similar to that of the ferrocenium/ferrocene couple. Further reduction to the formally monovalent (d(10)) dianion [Cu(I)(ttfasbz)](2-) may be achieved electrochemically. Computational chemistry demonstrates that the three redox states [Cu(ttfasbz)], [Cu(ttfasbz)](-), and [Cu(ttfasbz)](2-) are truly Cu(III), Cu(II), and Cu(I) complexes, respectively, and the potentially noninnocent ligand does not undergo any redox reactions.

4-(Prop-2-yn-1-yl-oxy)benzene-1,2-dicarbonitrile.

In the title compound, C(11)H(6)N(2)O, the complete mol-ecule is generated by the application of crystallographic twofold symmetry (the mol-ecule is disordered about this axis). The prop-2-yn-1-yl residue is slightly twisted out of the plane of the benzene ring [C-O-C-C torsion angle = 173.1 (3)°] and is orientated away from the nitrile substituents. In the crystal, supra-molecular chains along the a axis, arising from C-H⋯N inter-actions, are connected into stacks along the c axis by π-π inter-actions between the benzene rings [centroid-centroid distance = 3.6978 (6) Š= length of the c axis].

4,5-Diphen-oxy-benzene-1,2-dicarbo-nitrile.

In the title compound, C(20)H(12)N(2)O(2), the phenyl and benzene rings are mutually perpendicular, with the dihedral angle between the phenyl rings being 87.92 (16)° and those formed between the phenyl rings and the benzene rings being 73.68 (15) and 84.65 (15)°. Helical supra-molecular chains along [010], mediated by C-H⋯N inter-actions, are found in the crystal structure.

(1E,2E)-1,2-Bis(2,3,4-trimeth-oxy-benzyl-idene)hydrazine.

The title compound, C(20)H(24)N(2)O(6), was obtained as an unexpected product by the reaction of hydrazinium dithio-carbazate with 2,3,4-trimeth-oxy-benzaldehyde in refluxing ethanol. The mol-ecule lies on a center of inversion. The crystal packing is stabilized by weak inter-molecular C-H⋯O inter-actions.

N-[(E)-Quinolin-2-yl-methyl-idene]-1,2,4-triazol-4-amine hemihydrate.

The title hemihydrate, C12H9N5·0.5H2O, was isolated from the condensation reaction of quinoline-2-carbaldehyde with 4-amino-4H-1,2,4-triazole. The Schiff base mol-ecule adopts an E configuration about the C=N bond and is approximately planar, with a dihedral angle between the quinoline ring system and the 1,2,4-triazole ring of 12.2 (1)°. In the crystal, one water mol-ecule bridges two Schiff base mol-ecules via O-H⋯N hydrogen bonds. The Schiff base mol-ecules are inter-connected by π-π stacking inter-actions [centroid-centroid distances of 3.7486 (7) and 3.9003 (7) Å] into columns along [10].

Potential natural sensitizers extracted from the skin of Canarium odontophyllum fruits for dye-sensitized solar cells.

Possibility of use of dye extract from skin samples of a seasonal, indigenous fruit from Borneo, namely Canarium odontophyllum, in dye sensitized solar cells (DSSCs) are explored. Three main groups of flavonoid pigments are detected and these pigments exhibit different UV-vis absorption properties, and hence showing different light harvesting capabilities. When applied in DSSCs. The detected pigment constituents of the extract consist of aurone (maritimein), anthocyanidin (pelargonidin) and anthocyanidin (cyanidin derivatives). When tested in DSSC, the highest conversion efficiency of 1.43% is exhibited by cyanidin derivatives, and this is followed by conversion efficiencies of 0.51% and 0.79% for aurone and pelargonidin, respectively. It is shown that individual pigments, like cyanidin derivatives and pelargonidin, exhibit higher power conversion efficiency when compared to that of C.odontophyllum skin pigment mixture (with a conversion efficiency of only 0.68%). The results indicate a possibility of masking effects of the pigments when used as a mixture. The acidification of C.odontophyllum skin pigments with concentrated hydrochloric acid improves the conversion efficiency of the mixture from 0.68% to 0.99%. The discussion in this paper will draw data and observations from the variation in absorption and adsorption properties, the HOMO-LUMO levels, the energy band gaps and the functional group compositions of the detected flavonoids.

Biological activity of palladium(II) and platinum(II) complexes of the acetone Schiff bases of S-methyl- and S-benzyldithiocarbazate and the X-ray crystal structure of the [Pd(asme)2] (asme=anionic form of the acetone Schiff base of S-methyldithiocarbazate) complex.

Palladium(II) and platinum(II) complexes of general empirical formula, [M(NS)(2)] (NS=uninegatively charged acetone Schiff bases of S-methyl- and S-benzyldithiocarbazate; M=Pt(II) and Pd(II)) have been prepared and characterized by a variety of physicochemical techniques. Based on conductance, IR and electronic spectral evidence, a square-planar structure is assigned to these complexes. The crystal and molecular structure of the [Pd(asme)(2)] complex (asme=anionic form of the acetone Schiff base of S-methyldithiocarbazate) has been determined by X-ray diffraction. The complex has a distorted cis-square planar structure with the ligands coordinated to the palladium(II) ions as uninegatively charged bidentate NS chelating agents via the azomethine nitrogen and the mercaptide sulfur atoms. The distortion from a regular square-planar geometry is attributed to the restricted bite angles of the ligands. Antimicrobial tests indicate that the Schiff bases exhibit strong activities against the pathogenic bacteria, Bacillus subtilis (mutant defective DNA repair), methicillin-resistant Staphylococcus aureus, B. subtilis (wild type) and Pseudomonas aeruginosa and the fungi, Candida albicans (CA), Candida lypotica (2075), Saccharomyces cerevisiae (20341) and Aspergillus ochraceous (398)-the activities exhibited by these compounds being greater than that of the standard antibacterial and antifungal drugs, streptomycin and nystatin, respectively. The palladium(II) and platinum(II) complexes are inactive against most of these organisms but, the microbe, Pseudomonas aeruginosa shows strong sensitivity to the platinum(II) complexes. Screening of the compounds for their cytotoxicities against T-lymphoblastic leukemia cancer cells has shown that the acetone Schiff base of S-methyldithiocarbazate (Hasme) exhibits a very weak activity, whereas the S-benzyl derivative (Hasbz) is inactive. However, the palladium(II) complexes exhibit strong cytotoxicities against this cancer; their activities being more than that of the standard anticancer drug, tamoxifen. The [Pt(asme)(2)] complex exhibits a very weak cytotoxicity, whereas [Pt(asbz)(2)] is inactive against leukemic cells.

Heterocyclic dithiocarbazate iron chelators: Fe coordination chemistry and biological activity.

The iron coordination and biological chemistry of a series of heterocyclic dithiocarbazate Schiff base ligands is reported with regard to their activity as Fe chelators for the treatment of Fe overload and also cancer. The ligands are analogous to tridentate heterocyclic hydrazone and thiosemicarbazone chelators we have studied previously which bear NNO and NNS donor sets. The dithiocarbazate Schiff base ligands in this work also are NNS chelators and form stable low spin ferric and ferrous complexes and both have been isolated. In addition an unusual hydroxylated ligand derivative has been identified via an Fe-induced oxidation reaction. X-ray crystallographic and spectroscopic characterisation of these complexes has been carried out and also the electrochemical properties have been investigated. All Fe complexes exhibit totally reversible Fe(III/II) couples in mixed aqueous solvents at potentials higher than found in analogous thiosemicarbazone Fe complexes. The ability of the dithiocarbazate Schiff base ligands to mobilise Fe from cells and also to prevent Fe uptake from transferrin was examined and all ligands were effective in chelating intracellular Fe relative to known controls such as the clinically important Fe chelator desferrioxamine. The Schiff base ligands derived from 2-pyridinecarbaldehyde were non-toxic to SK-N-MC neuroepithelioma (cancer) cells but those derived from the ketones 2-acetylpyridine and di-2-pyridyl ketone exhibited significant antiproliferative activity.