Muhammad Mazhar

Organotin esters of 3-(2-furanyl)-2-propenoic acid: their characterization and biological activity

Abstract Multinuclear NMR and Mossbauer spectroscopy have been carried out for d- and triorganotin carboxylates derived from 3-(-2-furanyl)-2-propenoic acid. Their spectroscopic characterization showd that triorganotin carboxylates are either 4-coordinate monomers or 5-coordinate polymers with bridging carboxylate groups. Although a polymeric structure is favoured for most compounds in the solid state, the solution studies indicated that they exist as monomeric 4-coordinate species in non-coordinating solvents. Diorganotin carboxylates of the general formula R2Sn(OOCCHCHC4H3O)2 and dimeric [(R2SnOOCCHCHC4H3O)2O]2 are penta-coordinate in noncoordinating solvents while in the solid phase intra- or intermolecular interactions are possible. Moreover, we report the fluxional behaviour of carboxylate anions in dimeric distannoxanes. The biological activity of these organotin carboxylates proved them to be powerful biocides.

Mössbauer, multinuclear magnetic resonance and mass spectrometric studies of organotin carboxylates of m-methyltrans-cinnamic acid

Abstract The synthesis and spectroscopic characterization (1H, 13C, 119Sn NMR, 119mSn Mossbauer and mass spectrometry) of a series of organotin carboxylates of m-methyl trans-cinnamic acid are described. Different literature methods have been successfully applied for the qualitative structural characterization of these compounds. Triorganotin carboxylates are essentially penta-coordinate in the solid state with R3SnO2 geometry, while tetracoordinate in non-coordinating solvents. Diorganotin carboxylates with a 1:2 molar ratio (R2SnO: 2HOCOR′) are hexa-coordinate as solids, while there is an equilibrium between hexa- and penta-coordinated states in solution. Moreover, compounds with a 1:1 molar ratio (R2SnO: HOCOR′), adopt a characteristic tetraorganodicarboxylato distannoxane structural mode. Interesting results have been observed for tricyclohexyltin derivatives and stannoxanes. 2D NMR has been employed for the assignments of protons of high-spin systems.

Hydrogenosilanes: Pentacoordination and pseudorotation

Abstract A 1 H NMR study of pentacoordinated trihydrogenosilanes shows that there is only a very low energy barrier to isomerisation by pseudorotation at silicon. In contrast, this process is not detected over a large range of temperature for dihydrogeno silanes. The SiH bond has a high equatorial preference which stabilises the geometry of the trigonal bipyramidal structures.

Organotin(IV) Derivatives as Biocides: An Investigation of Structure by IR, Solution NMR, Electron Impact MS and Assessment of Structure Correlation with Biocidal Activity

A brief account is given of the synthesis, structural chemistry and the antibacterial, antifungal and cytotoxic effects of organotin complexes of 2-[(2,4-dichloroanilinocarbonyl)]benzoic acid. The unimolar and bimolar substitution products have been characterized by elemental analysis and spectral studies, including IR, 1H NMR, 13C NMR, 119Sn NMR, and mass spectra. The data support the binding of the oxygen atom to the tin atom in [R2Sn(OOCR’)2] and [R3Sn(OOCR’)] (R = Me, Bu, and Ph, R’ = 2-[(2,4-dichloroanilinocarbonyl)]benzoic acid). Based on these studies, with a coordination number of four, a distorted tetrahedral geometry has been proposed for the resulting derivatives in solution. The free ligand (R’/COOH) and its respective tin complexes were tested in vitro against a number of microorganisms to assess their biocidal properties and to correlate them with the structures of the derivatives.

1H, 13C, 119Sn NMR, 119mSn Mössbauer, Infrared and Mass Spectrometric Studies of Organotin Carboxylates of 2-(2,3-dimethylphenyl)Aminobenzoic Acid and their Effect on Microorganisms.

Abstract The synthesis of a new series of organotin carboxylates of 2-(2,3-dimethylphenyl)aminobenzoic acid is reported. Multinuclear NMR (1H, 13C, 119Sn) data have been used as a tool for determining their structures in non-coordinating solvents. Solid state structures have been proposed on the basis of IR and Mossbauer parameters. 2D NMR has been used for the assignments of high-spin systems. Screening tests of these compounds showed that they are highly active against various bacteria and fungi. Referee I: G. Eng Referee II: C. C. Cummins

Synthesis, Spectroscopic Characterization and Biological Studies of Organotin Derivatives of 2- (2,6-dichlorophenyl)aminophenylaceticacid

Abstract Infrared, multinuclear NMR, mass and Mössbauer spectral techniques have been used to characterize new organotin compounds of 2-(2,6-dichlorophenyl)aminophenyl-acetic acid anion with the general formulae R3SnL, R2SnL2 and R2Sn(Cl)L where R = CH3, C4H9, C6H5, C6H5CH2 and L = 2-(2,6-dichlorophenyl)-aminophenylacetic acid anion. These techniques were used to compare the geometry of these compounds as solids and in solution. Antibacterial and antifungal activities were determined in order to study their biological significance.

Arigid pentacoordinate silicon structure generalization of pseudorotation

Abstract Examination of an organosilicon compound with a structure very favorable for pentacoordination shows the generality of the pseudorotation at silicon for bi- and tri-functional compounds. In contrast monofunctional compounds do not undergo pseudorotation, the ΔG* being estimated to be > 20 kcal M−1.

Hexagonal structured Zn(1−x)CdxO solid solution thin films: synthesis, characterization and applications in photoelectrochemical water splitting

Hexagonal nanostructured zinc–cadmium oxide [Zn(1−x)CdxO where x = 0.08, 0.15, and 0.17] solid solution thin films were deposited on FTO coated glass substrates from a common solution of zinc acetate and a newly developed polymeric cadmium precursor by an aerosol-assisted chemical vapour deposition (AACVD) technique. The polymeric cadmium precursor [Cd3(TFA)4(OAc)2(THF)4]n (1) was synthesized by the reaction of cadmium(II)acetate dihydrate with triflouroacetic acid in THF solution and characterized by melting point, microanalysis, FTIR, 1H-NMR, thermogravimetry (TG/DTG) and single crystal X-ray analysis. The deposited thin films were characterized by powder XRD, SEM, EDX and UV-visible spectrophotometry, and tested for photoelectrochemical (PEC) water splitting to hydrogen and oxygen. The effect of various thin film deposition parameters such as solvent type, temperature and electrolyte concentration on PEC properties has been investigated. The SEM analysis illustrated that the morphology of the films changes significantly with the change of the solvent. The films deposited from THF solution have a needle-like appearance scattered vertically on the FTO-coated glass substrate. An optical band gap of 2.40 eV has been estimated by UV-visible spectrophotometry. The current–voltage characterization proved that the nanocrystalline hexagonal structured Zn0.83Cd0.17O electrodes exhibit an n-type semiconducting behaviour and the photocurrent was found to be strongly dependent on the deposition solvent, deposition temperature and electrolyte concentration. The maximum photocurrent density of 0.23 mA cm−2 at 0.55 V vs. Ag/AgCl/3 M KCl (∼1.23 V vs. RHE) was obtained for the Zn0.83Cd0.17O photoelectrode deposited at 500 °C for 45 min from 0.5 M solution of (1) and Zn(CH3COO)2·2H2O in THF.

1H, 13C, AND 119Sn NMR, IR, MASS, THERMAL, AND BIOLOGICAL STUDIES OF ORGANOTIN(IV) DERIVATIVES OF 4-p-(CHLOROPHENYL)-2-PHENYL-5-THIAZOLEACETIC ACID

ABSTRACT A series of di- and triorganotin(IV) carboxylates of 4-p-(chlorophenyl)-2-phenyl-5-thiazoleacetic acid has been synthesized and characterized by various instrumental techniques such as infrared, 1H, 13C, 119Sn NMR, mass spectrometry and thermal analysis. These compounds were also tested for their antibacterial and antifungal activities to study their biological significance.

SYNTHESIS AND SPECTRAL STUDIES OF BIS{DIALKYL- [TRANS-3-(2-THIOPHENYL)-2-PROPENOATO]TIN} OXIDES: CRYSTAL STRUCTURE OF {[(CH3)2SnO2C-CH=CH-C4H3S]2O}2

Synthesis and multinuclear studies of stannoxane of 3-(2-thiophenyl)-2-propenoic acid have been performed. Crystal structure of bis[(3-(2-thiophenyl)-2-propenoato)dimethyltin]oxide is presented. The unit cell is triclinic with space group PI, Z=2. Out of 3050 reflections, 2273 were unique with I > 2σ(7). The thiophene ring SI, C5, C6, C7 and C4 is staggered with an other ring containing Sla, C5a, C6a, C7a and C4a which describes the ring twist under the impact of radiation leading to disorder in the structural refinement. Of particular interest is the mode of 05 interactions. It forms an intra-molecular contact with Sn atom of the same molecule while an inter-molecular interaction with Sn atom of a symmetry related unit in the lattice. These intraand inter-molecular interactions result in the formation of an infinite one dimensional polymer.