Volume 39, Issue 1-2

Some new organotin(IV) complexes of the type R 2 Sn[OC(R′):CH(CH 3 )C:NR″O] (R=CH 3 , C 4 H 9 , C 6 H 5 ; R′=CH 3 , C 6 H 5 ; and R″=(CH 2 ) 2 , (CH 2 ) 3 ) have been synthesized by the reactions of diorganotin dichloride with the sodium salt of the corresponding bifunctional tridentate Schiff base ligands in unimolar ratio in refluxing tetrahydrofuran (THF). All these compounds have been characterized by elemental analyses, and their probable structures, in which the central tin atom is pentacoordinated, have been proposed on the basis of infrared (IR) and 1 H, 13 C and 119 Sn NMR and fast atom bombardment mass spectroscopic studies. The ligands, metal precursors and their corresponding diorganotin complexes have also been screened for antimicrobial activities.

Some new heteroleptic boron derivatives of the type [where R=CH 3 , R′=(CH 2 ) 2 (2a); (CH 2 ) 3 (2b); CH(CH 3 )CH 2 (2c), R=C 6 H 5 , R′=(CH 2 ) 2 (2d); (CH 2 ) 3 (2e); CH(CH 3 )CH 2 (2f)] have been synthesized by the reactions of tri-isopropyl borate with bifunctional tridentate Schiff bases and 2,2-dimethyl propane 1,3-diol in 1:1:1 molar ratio in refluxing benzene. Four isomers of corresponding heteroleptic derivatives 2a , 2b , 2e and 2f having the general formula [where R=CH 3 , R′=(CH 2 ) 2 ( 3a ); (CH 2 ) 3 ( 3b ), R=C 6 H 5 , R′=(CH 2 ) 3 ( 3e ); CH(CH 3 )CH 2 ( 3f ) have also been synthesized by adopting different synthetic two-step processes. All these compounds have been characterized by elemental analyses, and their tentative structures have been proposed on the basis of IR, 1 H, 13 C, 11 B NMR spectroscopic and FAB mass spectrometric studies. Schiff base ligands and their corresponding heteroleptic boron derivatives ( 2a–f ) have also been screened for antimicrobial activities against pathogenic bacteria and fungi.

New symmetrically para -substituted tetraphenylporphyrin Tl(III) salicylate complexes, having the general formula SA/5-SSATl(III)t(4-Y)PP (Y=-H, -CH 3 , -OCH 3 ); SA=salicylates and 5-SSA=5-sulfosalicylates, were synthesized and characterized by elemental analysis, optical absorption/emission studies, infrared spectrum, NMR studies ( 1 H, 205 Tl), thermal analysis and mass spectra; the complexes are in good consistency with experimental results. All the newly synthesized complexes exhibited good optical property, and thermogravimetric analysis (TGA) results showed their excellent thermal stability (>400°C). Macrocyclic complexes of Tl(III) ligate to axial ligand to form six-coordinate complex, the nature of which influences the photophysical properties of the former depending upon the spin-orbital coupling character of the axial ligand. A square-based pyramidal structure has been proposed on the basis of these studies. In addition, some of the synthesized complexes of thallium porphyrins were also screened for anti-bacterial activity. Cytotoxic activity of 5-SSATl(III)t (4-OCH 3 )PP evaluated against four human cancer cell lines exhibited strong (up to 90%) growth inhibition.

New Schiff bases 5-iodo-indol-2,3-dionehydrazinecarboxamide (L 1 H) and 5-iodo-indol-2,3-dionehydrazinecarbothioamide (L 2 H) and their organotin(IV) complexes have been synthesized. The biologically potent ligands interacted with the Sn(IV) metal ion in 1:1 and 1:2 molar ratios, respectively, in dry methanol. Tentative structural conclusions of organotin(IV) complexes are described with the support of elemental analyses, melting points, and molecular weight determinations, infrared, nuclear magnetic resonance ( 1 H, 13 C, and 119 Sn), and ultraviolet-visible light spectroscopic studies. The spectroscopic data showed that the ligands are monobasic bidentate, coordinating through nitrogen and sulfur/oxygen atoms. Thus, suitable trigonal bipyramidal geometry and octahedral geometry have been suggested for the 1:1, and 1:2 metal complexes, respectively. The ligands and their complexes have been tested against various microbes for their in vitro antimicrobial activities. All complexes exhibit good antibacterial activity against the two bacterial species Escherichia coli and Staphylococcus aureus and remarkable antifungal activity against the two fungi Fusarium semitectum and Aspergillus flavus with respect to their corresponding ligands. The DNA cleavage efficiency of the ligands and the complexes has also been examined and discussed using gel electrophoresis technique, which showed the cleavage of DNA by all the metal complexes and ligands.

The chemical and electrochemical equilibria involving mercurous and mercuric chlorides in the conditions, corresponding to the human stomach environment, were studied from the point of view of chemical thermodynamics. The Gibbs free energies of formation of various mercury and chlorine compounds, the equilibrium constants, and the electrode potentials of reactions involving these compounds at 37°C were calculated. The potential-pH diagrams of Hg22+-H2O,${\rm{Hg}}_2^{2 + }{\rm{ - }}{{\rm{H}}_2}{\rm{O,}}$ Cl - -H 2 O, and Hg22+-Cl--H2O${\rm{Hg}}_2^{2 + }{\rm{ - C}}{{\rm{l}}^{\rm{ - }}}{\rm{ - }}{{\rm{H}}_2}{\rm{O}}$ systems were plotted. The question of how toxic is calomel when ingested was discussed.

Metal contamination of soil is due to mining, manufacturing and use of synthetic products (e.g. pesticides, paints, batteries, industrial waste and industrial or domestic sludge) which is a serious environmental problem. Hence, determining chemical forms of metals in soils is important to evaluate their mobility or bioavailability. Both artificial and contaminated soils were sequentially extracted to fractionate metals into the water soluble fraction (WSF), exchangeable fraction (EF), bound to carbonate fraction, bound to metal oxide fraction, organically bound fraction (OBF) and residual fraction (RF). In the case of contaminated soil, Pb and Cr are found to be associated with the carbonate fraction while in artificial soil, Pb bound to WSF and Cr with the Fe/Mn fraction. Chemical properties such as pH, electrical conductivity (EC) and textural classification of concerned soils were also analyzed. Percentage recovery was calculated to check the reliability of processes both in Pb and Cr, and it was found to be more in Cr (66% and 84%) in both artificial and contaminated soil than Pb (5% and 34%) in both soils. Analyses of extracts were carried out by atomic absorption spectrometry (AAS). Results were interpreted in terms of environmental mobility or bioavailability of metals.

In this study, Zn 3 B 6 O 12 ·3.5H 2 O, a type of a zinc borate hydrate, was synthesized from the sodium borate mineral Na 2 B 4 O 7 ·5H 2 O. Two different zinc sources, i.e. ZnSO 4 ·7H 2 O and ZnCl 2 , were used in the hydrothermal synthesis. Products were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy. Product morphologies were studied using scanning electron microscopy (SEM). Then optical absorption characteristics and electrical properties were investigated. Based on these results, Zn 3 B 6 O 12 ·3.5H 2 O was obtained under many synthetic conditions as a single phase with high reaction efficiencies and sub-micrometer (100 nm to 1 μm) particle sizes. The electrical resistivity and optical energy gap were found as 8.8×10 10 Ω cm and 4.13 eV, respectively. The novelty obtained in this study is the synthesis of zinc borate hydrate compound with high crystallinity without using any modification agent or organic solvent.