Syntheses,Spectral, and Biological Studies of New Imines Derived From 5-Bromothiophene-2-Carboxaldehyde and Their Si(IV), Sn(IV) Complexes

The Schiff bases (imines) HL¹ and HL² have been synthesized by the reaction of 5-bromothiophene-2-carboxaldehyde with 4-amino-5-mercapto-1,2,4-triazole and 4-amino-3-ethyl-5-mercapto-1,2,4-triazole, respectively. Organosilicon(IV) and organotin(IV) complexes having the general formulae R₂MCl(L¹), R₂MCl(L²), R₂M(L¹)₂, R₂M(L²)₂, (M = Si, Sn; R = CH₃) were synthesized by the reaction of R₂MCl₂ with these Schiff bases in 1:1 and 1:2 molar ratio. The Schiff bases and their metal complexes have been characterized with the aid of elemental analyses, molar conductance, and spectroscopic studies, including UV, IR, ¹H, ¹³C, MS, ²⁹Si, and ¹¹⁹Sn NMR spectroscopy. On the basis of these studies, the resulting complexes have been proposed to have trigonal bipyramidal and octahedral geometries. In vitro activities of the Schiff bases and their metal complexes against some Gram positive and Gram negative bacteria and fungi have been carried out and described.     

Microwave-assisted synthesis of nitrogen-sulfur and nitrogen-oxygen donor ferrocene-containing ligands and their organotitanium(IV) and organozirconium(IV) complexes

The synthetic routes and spectroscopic studies of organotitanium(IV) and organozirconium(IV) complexes derived from azomethines, 1-acetylferrocenethiosemicarbazone (L¹H) and 1-acetylferrocenesemi-carbazone (L²H), have been carried out in 1 : 1 and 1 : 2 stoichiometric ratios. Azomethines and their complexes have been characterized by elemental analyses, conductance measurements, molecular weight determinations, and spectral studies. The electronic, IR, and ¹H NMR and ¹³C NMR spectral data indicate that azomethines act as bidentate ligands and coordinate to the metal (Ti or Zr) via nitrogen and the sulfur or oxygen atoms giving trigonal bipyramidal and octahedral geometries for the resulting complexes. All the ligands and their complexes have been screened for their biological activity on several pathogenic fungi and bacteria and were found positive in this respect. The text was submitted by the authors in English.     

Antimicorbial effects of newly synthesized organotin(IV) and organolead(IV) derivatives

Triorganotin(IV) and triorganolead(IV) derivatives of the types Me₃Sn(SCZ) and Ph₃Pb(SCZ) (where SCZ^? is the anion of a semicarbanzone ligand) have been synthesized by substitution reactions of trimethyltin chloride and triphenyl-lead chloride with semicarbazones derived from heterocyclic ketones. The resulting complexes have been characterized by elemental analyses, molecualr weight determinations and conductivity measurements. The mode of bonding has been established on the basis of infrared and ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopic studies. Some respresentative complexes have also been evaluated for their antimicrobial effects on different species of pathogenic fungi and bacteria; the results of these investigations have been reported in the present paper.     

Synthesis,characterization, reactivity,and electrochemical studies of manganese(IV) complexes of bis(2-hydroxy-1-naphthaldehyde)adipoyldihydrazone

Manganese(IV) complexes [Mn^IV(npah)(H₂O)₂] (1) and [Mn^IV(npah)(A)₂]?·?nH₂O (where A?=?py (2), 2-pic (3), 3-pic (4), 4-pic (5)) and Mn^IV(npah)(NN)] (NN?=?bpy (6) and phen (7)) have been synthesized from bis(2-hydroxy-1-naphthaldehyde)adipoyldihydrazone in methanol. The composition of the complexes has been established by elemental analyses. Complex 3 has been characterized by mass spectral data also. Structural assessment of the complexes has been based on data from molar conductance, magnetic moment, electronic, electron paramagnetic resonance, and infrared (IR) spectral studies. Molar conductances of the complexes in DMSO suggest non-electrolytes. Magnetic moment and EPR studies suggest +4 oxidation state for manganese in these complexes. Electronic spectral studies suggest six-coordinate octahedral geometry around the metal ions. IR spectra reveal that H₄npah coordinates to the metal in enol form. Reaction of the complexes with benzyl alcohol and SO₂ has been investigated. Cyclic voltammetric studies of the complexes have also been carried out.     

Synthesis,characterization, and antibacterial activity of triorganotin(IV) complexes of 2-methylphenol

The triorganotin(IV) complex Ph₃Sn(OPhMe-2) (1) has been synthesized by the reaction of Ph₃SnCl with NaOPhMe-2, while complexes of composition n-Bu₃Sn(OPhMe-2) (2) and Me₃Sn(OPhMe-2) (3) (where ?OPhMe-2 = ?OC₆H₄CH₃-2) have been obtained from the reaction of n-Bu₃SnCl and Me₃SnCl with 2-methylphenol in the presence of triethylamine in carbon tetrachloride. The complexes have been characterized by elemental analyses, molar conductance measurements, molecular weight determination, and IR, ¹H NMR, ¹³C NMR, and mass spectral studies. Thermal behavior of the complexes has been studied by TG and DTA techniques. The organotin(IV) complexes have also been screened for antibacterial activity and exhibit appreciable activity. The reactions of the complexes with 3- and 4-cyanopyridines yielded 1 : 1 adducts authenticated by physicochemical and IR and ¹H NMR spectral data.     

Synthesis and Properties of Mixed Ligand Complexes of Diorganotin(IV): Part(VII) – Synthesis and Characterisation of Some Antibacterial Dibenzoylmethane Diorganotin(IV)‐O‐alkyl Trithiophosphates

A series of some new mixed ligand complexes have been synthesized with an objective for evaluation as antimicrobials. Reactions of diorganotin(IV) dichloride with dibenzoyl methane and O‐alkyl trithiophosphates in a 1:1:1 molar ratio in refluxing benzene yield products of the type [PhCOCHCOPh]R₂Sn‐[SSH(S)POR'] [where R = Me, Bu, Ph; R' = Me, Et, Prⁱ, Buⁱ, Ph]. The newly synthesized complexes are light yellow colored crystalline solids, non‐volatile, soluble in common organic solvents, monomeric in nature and highly sensitive towards atmospheric moisture. These complexes are characterized by elemental analysis, IR and multinuclear NMR (¹H, ³¹P and ¹¹⁹Sn) spectral studies. Spectral studies of these complexes indicate that dibenzoyl methane and O‐alkyl trithiophosphate moieties are bidentate and the central tin atom is hexacoordinated in nature. A few of these compounds were tested for their antibacterial activity using standard drugs.     

Synthesis,characterization of Uranyl(VI), Th(IV), Zr(IV) mixed-ligand complexes with S-methyl-2-(4-methoxybenzylidine)dithiocarbazate and N-donor co-ligand,and their evaluation as antimicrobial agent

Schiff base, S-methyl-2-(4-methoxybenzylidine) dithiocarbazate as a primary ligand (HL₁), quinoline (L₂) as a co-ligand, and hydrated metal salts have been reacted in ethanol in 1:2:1 M ratio to produce mixed-ligand complexes of the type, [M(L₁)(L₂)].NO₃ [M = Uranyl(VI), Th(VI), Zr(IV)], The isolated products have been structurally investigated by elemental analyses, ¹H NMR, IR and UV–Vis studies. The electronic studies shows octahedral geometry for all the studied complexes, whereas the molar conductance data suggest an ionic nature. Density functional computation (DFT) studies are also carried out in order to determine the bonding inside the structure of the complexes. The studied mixed-ligand complexes showed moderate antibacterial activity when evaluated against four pathogenic bacteria: Shigella dysenteriae, Bacillus subtilis, Agrobacterium tumefaciens, and Escherichia coli. In addition, molecular docking analysis for all the complexes, using the CLC Drug Discovery Workbench software, showed that they virtually docked on S. dysenteriae, B. subtilis, A. tumefaciens, and E. coli.     

Organotin(IV) and organolead(IV) complexes as biocides and fertility regulators: synthetic,spectroscopic and biological studies

Biocidal, antifertility and spectroscopic aspects of organotin(IV) and organolead(IV) complexes with amino acids(L) and 2,2‐bipyridine(L′) are described with the support of elemental analysis, IR, ¹H, ¹³C, ¹¹⁹Sn and ²⁰⁷Pb NMR spectroscopy. The spectral data suggest that the ligand L acts in a monodentate and ligand L′ in a bidentate manner, coordinating through the nitrogen atoms. The complexes have been characterized on the basis of molecular weight determinations and conductivity measurements. The isolated products are coloured solids, soluble in dimethylsulfoxide (DMSO), dimethylformamide (DMF) and methanol. All the complexes are monomeric in nature, as indicated by their molecular weight determinations. Conductivity measurements in dry DMF show them to be non‐electrolytes. The complexes have been screened against a number of fungi and bacteria to assess their growth inhibiting potential. The results are positive. In addition to these studies, the complexes show good antimicrobial properties as compared with their starting materials. The testicular sperm density, sperm morphology, sperm motility, density of cauda epididymis, spermatozoa and fertility in mating trials and the biochemical parameters of the reproductive organs of rats were examined and are discussed in detail. Copyright © 2006 John Wiley & Sons, Ltd.     

Organosilicon(IV) and organotin(IV) complexes as biocides and nematicides: synthetic,spectroscopic and biological studies of N∩N donor sulfonamide imine and its chelates

A brief account is given of the synthesis and stereochemistry and the antibacterial, antifungal, nematicidal and insecticidal behaviour of organosilicon(IV) and organotin(IV) complexes of a biologically potent ligand, 2‐acetylfuransulfaguanidine. The unimolar and bimolar substitution products have been characterized by elemental analyses, conductance measurements, molecular weight determinations, and spectral studies, viz. IR, ¹H NMR, ¹³C NMR, UV, ²⁹Si NMR and ¹¹⁹Sn NMR spectra. The data support the binding of the nitrogen atom to the metal atom in R₃M(N^∩N), [R₂M(N^∩N)₂ and R₂M(N^∩N)Cl [(R = Me/Ph and M = Si(IV) and Sn(IV)] types of complex. Based on these studies, with coordination number five and six a trigonal bipyramidal and an octahedral geometry have been proposed for the resulting derivatives. The free ligand (N^∩NH) and its respective metal complexes were tested in vitro against a number of microorganisms to assess their antimicrobial properties. The results are indeed positive. In addition to these studies, the complexes also show good nematicidal and insecticidal properties. The results of these findings have been discussed in detail. Copyright © 2004 John Wiley & Sons, Ltd.     

Bioactive versatile azomethine complexes of organotin(IV) and organosilicon(IV)

Diorganotin(IV) and diorganosilicon(IV) derivatives of the types R₂MCl(TSCZ) and R₂M(TSCZ)₂ (where TSCZ is the anion of a thiosemicarbazone ligand, R=Ph or Me and M=Sn or Si) have been synthesized and characterized by elemental analyses, molecular weight determinations and conductivity measurements. The mode of bonding has been established on the basis of IR and ¹H, ¹³C ²⁹Si and ¹¹⁹Sn NMR spectroscopic studies. Some of the representative complexes have also been evaluated for their antimicrobial effects on different species of pathogenic fungi and bacteria in vivoas well as in vitro.The results of these investigations are reported. © 1998 John Wiley & Sons, Ltd.     

New coordination compounds of tin(IV) with Schiff bases of dialdehyde/diketones and sulpha drugs

New tin(IV) complexes have been synthesized by the reaction of dimethyltindichloride with nitrogen donor ligands. The ligands used in these studies were condensation products of dialdehydes/diketones and sulpha drugs. Their structural studies have been carried out on the basis of elemental analyses, ultraviolet, infrared, ¹H-NMR and ¹¹⁹Sn-NMR spectral studies. The monomeric and non-electrolytic nature of these complexes has been confirmed by their molecular weight determination and conductance measurements.     

Preparation and characterization of diphenyllead(IV) and triphenyllead(IV) complexes with N-protected amino-acids and the dipeptides

The diphenyllead(IV) derivatives of N-benzoyl-(glycine, DL -alanine); N-formyl and N-acetyl-L -phenylalanine; N-monochloroacetyl-L -phenylalanine; N-benzoyl-(glycylglycine, DL -alanylglycine), and N-formyl- N-acetyl- and N-monochloroacetyl-(L -phenylalanylglycine) have been prepared in 1:2 molar ratio by reaction of diphenyllead dichloride with the appropriate amino-acid or dipeptide. Corresponding triphenyllead(IV) derivatives have been prepared in 1:1 molar ratio by reaction of triphenyllead chloride with the thallium(I) salts of the amino-acid or the dipeptide. These complexes have been characterized by elemental analysis, IR and ¹H NMR spectral studies. A polymeric hexacoordinated octahedral structure for diphenyllead(IV), and a five-coordinated distorted trigonalbipyramidal chain-type structure for triphenyllead(IV), complexes is confirmed by IR spectra. The carboxylate group acts in a bidentate manner, not as in diorgano and triorganotin(IV) complexes with these acids, where it is monodentate. The available bonding sites such as amide and peptide carbonyl (CO) and amide and peptide nitrogen atoms are not involved in bonding with lead (IV) and thus are available for bonding with the biological systems. The presence of different N-protecting groups does not affect the coordination sites around lead(IV). The triphenyllead(IV) compounds are relatively more stable than the diphenyllead(IV) compounds.     

Synthesis,characterization, semi-empirical study,and biological activities of organotin(IV) complexes with cyclohexylcarbamodithioic acid as biological active ligand

Cyclohexylcarbamodithioic acid has been synthesized by the reaction of cyclohexylamine with carbon disulfide at room temperature. Its complexes have been synthesized by the reaction of cyclohexylcarbamodithioic acid with organotin(IV) chlorides in 1?:?1/1?:?2 molar ratio. The ligand and complexes have been characterized by elemental analysis, infrared (IR), and multinuclear (¹H, ¹³C, and ¹¹⁹Sn) NMR spectroscopy. Elemental data show good agreement between calculated and found values of carbon, hydrogen, nitrogen, and sulfur. IR data show that the ligand is bidentate and complexes exhibit a five-coordinate geometry in the solid state, which is also confirmed by semi-empirical studies. NMR data show that the complexes exhibit tetrahedral geometry in solution state. The ligand and its complexes were screened for their in vitro mutagenic, antimicrobial, MIC, antioxidant activities, and cytotoxicity. Biological screening data demonstrate that complexes show significant activity against various bacterial and fungal strains and are good antioxidants. The cytotoxicity data show positive lethality for complexes as compared to ligand and can play a very significant role in drug development.     

Thermal Studies on Some Ionic Chelates of Hafnium(IV)

Ionic chelate complexes of kojic acid(I) and hafnium(IV) of the type [(η⁵-C₅H₅)₂HfL]⁺[MCl₃]^– (II)[HL=kojic acid; M=Zn(II), Cd(II), Hg(II), Cu(II)] have been synthesised and characterised by spectral studies (IR, UV, ¹H NMR and ¹³CNMR). Thermogravimetric (TG) and differential thermal analytical (DTA) studies have been carried out for these complexes and from the TG curves, the order and apparent activation energy for the thermal decomposition reactions have been elucidated. The various thermal studies have been correlated with some structural aspects of the complexes concerned. From DTA curves, the heat of reaction has been calculated. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis,structural studies and biological activity of dioxomolybdenum(VI), dioxotungsten(VI), thorium(IV) and dioxouranium(VI) complexes with 2-hydroxy-5-methyl and 2-hydroxy-5-chloroacetophenone benzoylhydrazone

New complexes of MoO₂(VI), WO₂(VI), Th(IV) and UO₂(VI) with aroyl hydrazones have been prepared and characterized by various physicochemical methods. Elemental analysis suggested 1 : 1 metal : ligand stoichiometry for MoO₂(VI), WO₂(VI), and UO₂(VI) complexes whereas 1 : 2 for Th(VI) complexes. The physicochemical studies showed that MoO₂(VI), Th(IV) and UO₂(VI) complexes are octahedral. The electrical conductivity of these complexes lies in the range 1.00 × 10⁻⁷−3.37 × 10⁻¹¹Ω⁻¹ cm⁻¹ at 373 K. The complexes were found to be quite stable and decomposition of the complexes ended with respective metal oxide as a final product. The thermal dehydration and decomposition of these complexes were studied kinetically using both Coats-Redfern and Horowitz-Metzger methods. It was found that the thermal decomposition of the complexes follow first order kinetics. The thermodynamic parameters of the decomposition are also reported. The biological activities of ligands and their metal complexes were tested against various microorganisms.     

Synthesis,characterization and antimicrobial activity of triorganotin(IV) derivatives of some bioactive Schiff base ligands

Triorganotin(IV) complexes of the type Me₃Sn[OC(R¹):CH(CH₃)C:NR²OH] and Ph₃Sn[OC(R′):CH(CH₃)C:NR″OH] (R′ = ─CH₃, ─C₆H₅; R″ = ─(CH₂)₂─, ─(CH₂)₃─) have been synthesized by the reactions of trimethyl/phenyltin(IV) chloride with the sodium salt of corresponding Schiff base ligands in unimolar ratio in refluxing tetrahydrofuran. All these compounds have been characterized using elemental analyses and their probable structures have been proposed on the basis of infrared, ¹H NMR, ¹³C NMR, ¹¹⁹Sn NMR and mass spectroscopic studies. In the trimethyltin(IV) derivatives the central tin atom is tetracoordinated, whereas in the analogous triphenyltin(IV)derivatives the central tin atom is pentacoordinated. All these ligands, metal precursors and corresponding triorganotin(IV) complexes have been screened for antimicrobial activities. A comparison of activities of the ligands and their corresponding triorganotin(IV) derivatives has been made. Attempts have also been made to relate the activity to the structure of these compounds.     

Green synthesis of new Ge(IV) complexes with bio-potent ligands and their antimicrobial,DNA cleavage,and antioxidant activities

Green microwave supported synthesis, spectral, antimicrobial, DNA cleavage, and antioxidant studies of Ge(IV) complexes with bio-potent ligands, 1-acetylferrocenehydrazinecarboxamide (L¹H) and 1-acetylferrocenehydrazinecarbothioamide (L²H) have been carried out. The ligands and their respective complexes have been characterized on the basis of elemental analysis, IR, ¹H and ¹³C NMR spectra, and X-ray powder diffraction studies. The ligands are coordinated to the Ge(IV) via azomethine nitrogen and thiolic sulfur atom/ enolic oxygen atom. Both ligands and their complexes demonstrated appreciable fungicidal and bactericidal properties. The metal complexes demonstrated stronger antimicrobial than the respective free ligands. DNA cleavage activity of the complexes study revealed higher activity of the complexes than the ligands. Antioxidant activity of the complexes was tested for their hydrogen peroxide scavenging.     

Schiff base supported mononuclear organotin(IV) complexes: Syntheses,structures and fluorescence cell imaging

Three mononuclear organotin(IV) complexes supported by Schiff bases have been synthesized. The complexes [(C₆H₅)₂Sn(L)] ( 1 ), [(t‐Bu)₂Sn(L)] ( 2 ) and [(t‐Bu)₂Sn(L')] ( 3 ) (L, L' = deprotonated Schiff bases) were obtained in good yield by the reaction of Schiff bases H ₂ L or H ₂ L′ with corresponding diorganotin dichlorides respectively. All newly synthesized complexes were characterized by means of FT‐IR spectroscopy, elemental analysis and multinuclear (¹H, ¹³C and ¹¹⁹Sn) NMR spectroscopy. In addition, single crystal X‐ray diffraction analyses were employed to establish the solid state molecular structures of these complexes. The structures of 1 – 3 reveal that all complexes are mononuclear with a five‐coordinated tin(IV) centre in it. The absorption and emission properties of all complexes have been investigated. Moreover, cytotoxicity and fluorescence cell imaging studies of theses complexes have been performed.     

Chloro-diorganotin(IV) complexes of 4-methyl-1-piperidine carbodithioic acid: Synthesis, X-ray crystal structures, spectral properties and antimicrobial studies

Chloro-diorganotin(IV) complexes of 4-methyl-1-piperidine carbodithioic acid (4-MePCDTA) have been synthesized by the reaction with diorganotin dichloride in 1:1 molar ratio in anhydrous toluene. These newly synthesized complexes have been characterized by elemental, IR, multinuclear NMR (¹H and ¹³C) and mass spectrometric studies. The crystal structures of complex 1 [Me₂SnCl(4-MePCDT)] and 3 [Ph₂SnCl(4-MePCDT)] have been determined by X-ray single crystal analysis, which show trigonal bipyramid geometry. These complexes were tested for their antimicrobial activity against six different plant and human pathogens. The screening results show that the complexes exhibit higher antibacterial and antifungal activity than the free ligand.