Synthetic, structural, and antimicrobial studies of organotin(IV) complexes of semicarbazone, thiosemicarbazone derived from 4-hydroxy-3-methoxybenzaldehyde

Reaction of dibutyltin dichloride, dimethyltin dichloride, and tributyltin chloride with ligands derived from thiosemicarbazone and semicarbazone leads to the formation of a new series of organotin(IV) complexes of general formula R₂SnCl₂·L and R₃SnCl·L (where L ligands derived from the condensation of thiosemicarbazide and semicarbazide with 4-hydroxy-3-methoxybenzaldehyde). The authenticity of these ligands and their metal complexes have been established on the basis of elemental analysis, conductance measurements, molecular weight determinations, infrared, ¹H NMR, ¹³C NMR, ¹¹⁹Sn NMR, and UV spectral studies. These studies showed that the ligands coordinate to the metal atom in a bidentate. An octahedral structure is proposed for the organotin(IV) complexes. The ligands and its metal complexes are screened for their antimicrobial activities against some Gram-positive and Gram-negative bacteria, and fungus. The studies demonstrated that metalation can increase the antimicrobial activity rather than the free ligands.     

Interference of tributyltin(IV)chloride on the vascular plant cells

In the recent past years, interest in the environmental impact of organotin(IV) compounds has risen markedly. Considering that most data in the scientific literature refers to the animal kingdom and not to higher plants cells, we tested the effects of organotin compounds on vascular plant cells, by studying the interaction of tributyltin chloride (TBTCl) with Allium cepa, Solanun tuberosum and Solanum melongena, vascular plants that are directly involved in the human food chain. The TBTCl effects on mitotic metaphase plates, on pollen grains and on both microtubers and adult tuber parenchymatic cells were investigated and the concentrations of TBTCl inside the treated parenchymatic cells were determined through ICP‐mass spectrometry. Oxygen and chlorophyll productions were also determined. The obtained results showed that TBTCl influenced not only morphology, but also the physiology of the vegetable cells since, despite the low concentrations used, the stress the cells were submitted to was experimentally confirmed. Moreover, the increase in the tin concentration in the cells, with increasing incubation time, showed that TBTCl possesses a very high capacity to be bioaccumulated and, as a consequence, it is able to enter the food chain. Copyright © 2006 John Wiley & Sons, Ltd.     

Interaction of trialkyltin(IV) chlorides with sarcoplasmic reticulum calcium ATPase

The interaction of the organotin compounds trimethyltin(IV) and tributyltin(IV) chlorides with the calcium pump from sarcoplasmic reticulum membranes was studied. It was found that the presence of calcium fully protects against the inhibitory effect of both organotin compounds. However, the apparent affinity of the protein for tributyltin chloride is two orders of magnitude higher than for trimethyltin chloride (K_0.5 values of 14 µ m and 1.4 m m , respectively). Studies of intrinsic fluorescence of the Ca²⁺‐ATPase and enzyme phosphorylation by ATP and Pi support the hypothesis that the inhibitory properties of trialkyltin compounds are due to the inhibition of calcium binding to the high‐affinity binding sites of the Ca²⁺‐ATPase. This suggests that there is a specific interaction between the trialkyltin compounds and the calcium binding sites of the protein. The effect of trialkyltin compounds on Ca²⁺‐ATPase was also addressed by differential scanning calorimetry to assess the thermal transition of the protein denaturation, and by infrared spectroscopy in the absorption region corresponding to the amide I band (1600–1700 cm^?1) to observe changes in the secondary structure of the protein. We conclude that the interaction of trialkyltin compounds with Ca²⁺‐ATPase reduces the affinity and cooperativity for calcium binding and, consequently, the inhibition of ATPase activity. These events are accompanied by changes in the secondary structure of the protein, including loss of α‐helix structure and a concomitant increase in protein aggregation or unfolding. The activity of trialkyltin compounds on the Ca²⁺‐ATPase is discussed in relation to their solubility in water and in the lipid phase. Copyright © 2012 John Wiley & Sons, Ltd.     

Organometallic complexes with biological molecues,part 3. in vivo cytotoxicity of diorganotin (IV) chloro and triorganotin (IV) chloro derivatives of penicillin g on chromosomes of aphanius fasciatus (pisces,cyprinodontiformes)

In order to obtain a continuous source of mitotic metaphases, gill tissue of Aphaius fasciatus (Pisces, Cyprinodontiformes) has been successfully employed. Results gathered after exposure of fish to R₂SnClpenG, R₃SnClpenGNa, to the parents R₂SnCl₂, R₃SnCl and to penGNa (penGNa = penicillinGNa; R = methyl, butyl and phenyl) suggest that both the parent organotin (IV) chloride and organotin (IV) chloropenG derivatives are toxic while penGNa exerts no significant toxic activity. Essentially, all of the chromosome abnormalities are classifiable as irregularly staining of chromosomes, breakages, side-arm bridges or pseudochiasmata.     

Speciation and determination of tin(IV) and organotin compounds in sea-water by hydride generation-atomic-absorption spectrometry with an electrically heated long absorption cell

A method is described for the determination of nanogram or subnanogram amounts of Sn(IV) and the halides of methyltin, dimethyltin, trimethyltin, n-butyltin, dibutyltin, and tributyltin. These compounds are volatilized from water samples by hydride generation, collected on a chromatographic stationary phase, desorbed in order of increasing boiling point, and detected by atomic-absorption spectrometry with atomization in a long electrothermally heated alumina tube furnace. The absolute detection limits are in the range 0.4-1.5 ng with a reproducibility of 4-15% for inorganic tin and organotin compounds.     

Plasma Membrane Perturbation Induced by Organotins on Erythrocytes from Salmo irideus Trout

Tributyltin chloride and its degradation products monobutyltin and dibutyltin act as water pollutants, owing to the use of tributyltin chloride as a biocide in marine paint formulations. These compounds are lipid-soluble and undergo bioaccumulation and bioconcentration. Salmo irideus trout erythrocytes were studied to evaluate the possible effects of these compounds on freshwater fish, which could be exposed to long-term effects due to bioaccumulation of organotins. Data showed that tributyltin increases the haemolysis rate, starting at 10 μM, while dibutyltin has a scant protective effect at each concentration tested. Similar studies were performed in the presence of carbon monoxide (CO), which is protective against membrane oxidative stress due to haemoglobin (Hb) auto-oxidation. In these conditions all the organotins tested induced an increase in the haemolysis rate. These results suggest that the consequence of auto-oxidation of Hb could condition the effects of some organotin compounds. Steady-state fluorescence of probes embedded in the lipidic part of the membrane was used to evaluate the modifications induced by organotins to the physico-chemical state of phospholipids.     

The small‐scale preparation and NMR characterization of isotopically enriched organotin compounds

Synthetic methods for the small‐scale laboratory preparation of isotopically enriched dibutyltin dichloride, dibutyltin di‐iodide, tributyltin chloride, tributyltin iodide, diphenyltin dichloride, triphenyltin chloride and triphenyltin iodide have been successfully established. Organotin iodides were prepared from redistribution reactions between tin(IV) iodide and the corresponding tetraorganotin, with the exception of dibutyltin di‐iodide, which was prepared directly from the reaction between tin metal and iodobutane. The development of novel procedures for the dealkylation/dearylation of tetraorganotins by acid hydrolysis produced superior yields of tributyltin chloride and diphenyltin dichloride in comparison with redistribution reactions. Organotin iodide redistribution reaction products were converted to their chloride analogues via the fluoride salts using an aqueous ethanolic solution of potassium fluoride. The insolubility of organotin fluoride salts was exploited to isolate and purify the isotopically enriched compounds, and to prevent losses during the purification procedure. The nuclear magnetic resonance (NMR) spectroscopic study of ‘natural abundance’ and isotopically enriched organotin compounds gave proton (¹H) and carbon‐13 (¹³C) spectra for butyltins, Bu_4−nSnX_n, and phenyltins, Ph_4−nSnX_n (X = I, Cl), allowing the assignment of ­¹H and ¹³C chemical shifts, and ¹¹⁹Sn–¹³C and ¹¹⁷Sn–¹³C coupling constants. The ¹³C NMR spectroscopic analysis of ¹¹⁷Sn‐enriched organotin compounds has allowed the assignment of certain resonances and tin–carbon coupling constants which were previously unobservable. The spectral patterns show that Δ(¹H) and Δ(¹³C) values are sensitive to structural changes, and that ¹³C shielding decreases with an increase in the electronegativity of the substituent. The tin–carbon coupling constants are also sensitive to structural changes, and for alkyl and aryl compounds the couplings decrease in the order ¹J > ³J > ²J > ⁴J. The ¹³C chemical shift values and the magnitude of tin–carbon coupling constants are shown to be solvent‐dependent. The ¹³C spectra of the isotopically enriched compounds show that the degree of isotopic enrichment and the nature of the isotope used (magnetic or non‐magnetic) are reflected in the spectral pattern obtained. Copyright © 2000 John Wiley & Sons, Ltd.     

Determination of organotin compounds in environmental samples by supercritical fluid extraction and gas chromatography with atomic emission detection

The extraction of six tetraalkyltin and seven ionic organotin compounds from spiked topsoil samples with supercritical carbon dioxide and carbon dioxide modified with 5 percent methanol was investigated. Analysis of the soil extracts was performed by gas chromatography with atomic emission detection. Retention times, minimum detectable concentrations, and detector linear ranges are included for nine organotin compounds (seven of the nine compounds were derivatized with n-pentylmagnesium bromide prior to gas chromatographic analysis). A 2³ factorial experimental design was used to study the effect of three variables (pressure, temperature, and extraction time) on compound recovery. The results indicate that the tetraalkyltin compounds are extracted from topsoil samples with recoveries ranging from 90 to 110 percent. Recoveries for the ionic organotin compounds ranged from 50 to 75 percent for trimethyltin chloride, triethyltin bromide, and tributyltin iodide; they were below 20 percent for dimethyltin dichloride, dibutyltin dichloride, diphenyltin dichloride, and butyltin trichloride. When sodium diethyldithiocarbamate was added to the soil samples prior to extraction, followed by extraction with carbon dioxide modified with 5 percent methanol, recoveries ranged from 70 to 90 percent for trimethyltin chloride, triethyltin bromide, dimethyltin dichloride, tributyltin iodide, and dibutyltin dichloride; recoveries were approximately 40 percent for butyltin trichloride and diphenyltin dichloride.     

Tin(IV) cyanoximates: synthesis, characterization, and cytotoxicity

In recent years, numerous organotin(IV) derivatives have exhibited remarkable cytotoxicity against several types of cancer. However, the properties of the cyanoxime-containing organotin(IV) complexes are unknown. Previously, it has been shown that cyanoximes displayed an interesting spectrum of biological activity ranging from growth-regulation to antimicrobial and pesticide detoxification actions. The work presented here attempts to combine the useful properties of both groups of compounds and investigate the likely antiproliferating activity of the new substances. A series of 19 organotin(IV) complexes, with nine different cyanoxime ligands, were anaerobically prepared by means of the heterogeneous metathesis reaction between the respective organotin(IV) halides (Cl, Br) and ML (M=Ag, Tl; L=cyanoximate anion), using an ultrasound in the CH3CN at room temperature. The compounds were characterized using spectroscopic methods (UV-visible, IR, 1H,13C NMR, 119Sn M?ssbauer) and X-ray analysis. The crystal structures of the complexes revealed the formation of two types of tin(IV) cyanoximates: mononuclear five-coordinated compounds of R4-xSnLx composition (R=Me, Et, n-Bu, Ph; x=1, 2; L=cyanoximate anion), and the tetranuclear R8Sn4(OH)2O2L2 species (R=n-Bu, Ph). The latter complex contains a planar [Sn4(OH)2O2]2- core, consisting of three adjacent rhombs with bridging oxo and hydroxo groups. The tin(IV) atoms are five-coordinated and have distorted trigonal-pyramidal surrounding. This is the first instance when the organic anions were found to act as monodentate O-bound planar oxime ligands. All of the compounds were studied in vitro for antiproliferating activity, using human cervical cancer HeLa and WiDR colon cancer cell lines; cisplatin was used as a positive control substance. The two dibutyltin(IV) cyanoximates showed cytotoxicity similar and greater to that of cisplatin.     

Poly(vinyl chloride) stabilisation with organotin compounds: Part IV—Catalysis of the reverse reaction: Addition of HCl to double bonds

The addition of HCl to 2–4 hexadiene in chlorinated solvents leads to an equimolar mixture of isomers of chlorohexene of which the 2–3 isomer (chloro-2-hex-3-ene) is kinetically more favoured than the 4-2 (chloro-4-hex-2-ene). The reaction is catalysed by Lewis acids such as the organotin chlorides, in the order of their Lewis acidity, in the same way as the dehydrochlorination of the chlorohexenes and their isomerisation. The same carbocation intermediate is believed to be involved in these reactions and its formation can be catalysed by the Lewis acid. It may also be inhibited by organotin chlorides such as tributyltin chloride, which reacts with HCl to give dibutyltin dichloride and butane, and thus inhibits the formation of the catalyst charge transfer complex between HCl and the diene. Furthermore, because the disappearance of hexadiene, through oligomerisation, is shown to be catalysed less by organotin chlorides than by ZnCl₂, the yield of HCl addition in the presence of tin compounds is higher.     

HPTLC analysis of organotin compounds in preservative solutions and preservative-treated wood

A high-performance thin-layer chromatographic (HPTLC) method is described for the determination of tributyltin compounds (bis(tri-n-butyltin) oxide, TBTO, and tri-n-butyltin naphthenate, TBTN) and their degradation products (dibutyltin and monobutyltin compounds). The organotin compounds are extracted from wood with ethanol containing 0.5% (v/v) of hydrochloric acid and the separation of the defferent kinds of organotin compounds is achieved by thin-layer chromatography. The sample spots are measured using a scanning densitometer after decomposing the organotin compounds to inorganic tin by ultraviolet irradiation and visualization of the spots with pyrocatechol violet. Applications of the method to detection and quantification of organotin compounds in preservative solutions, in recently impregnated wood, and in wood samples from five-year-old window frames are described.     

Structural studies on organotin(IV) complexes formed with ligands containing {S,N,O} donor atoms

A number of complexes of ligands containing {O,N,S} donor atoms (2,3,4,6-tetra-O-acetyl-b-D-thioglucopyranoside, 1-thio-b-D-glucose, 2-aminomercaptopurine, 4-amino-2-mercaptopyrimidine and 2-amino-6-mercaptopurine-9-D-riboside) with di-n-butyltin(IV) oxide, diphenyltin(IV) oxide, tribenzyltin(IV) chloride, and trimethyltin(IV) chloride were prepared in the solid state. It was found that the complexes contain the organotin(IV) moiety and the ligand in a ratio of 1:1 or 2:1. The FTIR and Raman spectra clearly demonstrated that the organotin(IV) moieties react with the {S} atom of the ligands, while di-n-butyltin(IV) oxide is coordinated to the deprotonated hydroxy group. In several cases, the basic part of the ligands also participates in complex formation. Comparison of the experimental Mössbauer D values with those calculated on the basis of the pqs concept revealed that the organotin(IV) moiety has trigonal-bipyramidal geometry, and in certain cases tetrahedral geometry too. Some of the complexes contain the organotin(IV) cation in two different surroundings.     

Organotin(IV) complexes with 2-hydroxynaphthaldehyde-N(4)-ethylthiosemicarbazone: Synthesis,characterization, and in vitro antibacterial activity

Four new organotin(IV) complexes with 2-hydroxynaphthaldehyde-N(4)-ethylthiosemicarbazone [(H₂DNET), (1)] of the type [MeSnCl(DNET] (2), [BuSnCl(DNET)] (3), [PhSnCl(DNET)] (4), and [Ph₂Sn(DNET] (5) have been synthesized by the direct reaction of H₂DNET (1) with organotin(IV) chloride(s) in the presence of potassium hydroxide in absolute methanol. All the compounds were characterized by elemental analyses, molar conductivity, UV-Vis, IR, ¹H, ¹³C, and ¹¹⁹Sn NMR spectral studies. The molecular structure of ligand (1) has been confirmed by X-ray single crystal diffraction. Spectroscopic data clearly suggested that Sn(IV) center is coordinated with the ONS tridentate ligand (H₂DNET) and exhibits a five-coordinate geometry in solution. Antibacterial studies were carried out in vitro against four bacterial strains. All organotin(IV) compounds (2–5) showed good activity against various bacteria but lower activity than the reference drug (Ciprofloxacin). The results demonstrate that organic groups attached to tin(IV) moiety have significant effect on their biological activities. Among them, diphenyltin(IV) derivative 5 exhibits significantly good activity than the other organotin(IV) derivatives (2–4).     

Preparation of pentylated organotin standards for use in trace analysis with gas chromatography

A method for the preparation and purification of pentylated derivatives is described for nine organotin compounds that are relevant in environmental analysis (tributyltin acetate, dibutyltin dichloride, butyltin trichloride, triphenyltin chloride, diphenyltin dichloride, phenyltin trichloride, tricyclohexyltin hydroxide (cyhexatin), dicyclohexyltin dibromide and bis (trineophyltin) oxide (fenbutatinoxide)). The compounds are synthesized on a 100 mg scale and purified by column chromatography. Purity checks were performed with gas chromatography with mass selective detection. The mass spectrum of pentyltrineophyltin is presented.     

Tin-Naphthalene Sulfonic Acid Complexes as Photostabilizers for Poly(vinyl chloride)

Poly(vinyl chloride) degrades when exposed to ultraviolet light for long durations; therefore, the photostability of polymeric materials should be enhanced through the application of additives. New organotin complexes containing 4-aminonaphthalene-1-sulfonic acid were synthesized and their role as poly(vinyl chloride) photostabilizers were evaluated. The reaction of 4-amino-3-hydroxynaphthalene-1-sulfonic acid and appropriate di- or trisubstituted tin chloride (triphenyltin chloride, tributyltin chloride, dibutyltin dichloride, and dimethyltin dichloride) in methanol under reflux gave the corresponding tin-naphthalene complexes with yields of 75%–95%. Elemental analyses and spectroscopic techniques including infrared and nuclear magnetic resonance (proton and tin) were used to confirm their structures. The tin complexes were added to poly(vinyl chloride) to produce thin films that irradiated with ultraviolet light. Various parameters were assessed, such as the weight loss, formation of specific functional groups, changes in the surface due to photoirradiation, and rate constant of photodegradation, to test the role played by the organotin complexes to reduce photodegradation in polymeric films. The results proved that organotin complexes acted as photostabilizers in these circumstances. The weight loss, formation of fragments containing specific functional groups, and undesirable changes in the surface of polymeric films were limited in the presence of organotin complexes. Organotin complexes containing three phenyl groups showed the most desirable stabilization effect. These act as efficient primary and secondary photostabilizers, and as decomposers for peroxides. In addition, such an additive inhibits the dehydrochlorination process, which is the main cause of poly(vinyl chloride) photodegradation.     

Structural chemistry of organotin(IV) complexes

The amazing structural diversity in organotin compounds is discussed in the systems containing -O and -S donor ligands. It is demonstrated that there exist a fascinating range of structural diversity for organotin(IV) complexes, including differences in coordination number and molecular geometry. The difference in structure is correlated with the nature of tin and ligand bonded R groups. Despite the large number of different structures found in organotin(IV) carboxylates, there is limited range of coordination geometries about the Sn atom. The four coordinated Sn atom in triorganotin(IV) complexes is invariably distorted tetrahedral and five coordinated Sn is distorted trigonal bipyramidal. A large range has been observed for diorganotin carboxylate structures, where five, six and seven coordinate geometries have been reported. The Sn atom in mono-organotin has only been demonstrated to exist in distorted octahedral geometries (the single exception being a pentagonal bipyramidal geometry). In the case of organotin(IV) complexes of S donor ligands, it has been shown that there exists a rich diversity in Sn atom geometries and coordination modes of the sulfur donor ligands themselves. As in related carboxylate systems, the assignment of coordination numbers to the Sn centers in some compounds is controversial. As a general trend, it has been shown that, the overall coordination number at the Sn atom decreases with the increasing number of organic substituents at the Sn atom. This phenomenon is usually achieved by increased asymmetry in the mode of coordination of the sulfur donor ligands.     

Effects of tin(IV) chloride and of organotin compounds on aquatic micro-organisms

The growth response of the alga Chlorella kessleri and the euglenoid Euglena gracilis has been studied as a model system to determine the effects of a tin salt (SnCl₄·5H₂O) and of some organotin (OT) derivatives, namely tetrabutyltin (TeBT), tributyltin (TBT) and tributyltin oxide (TBTO). Abiotic degradation was studied as well. Cells were exposed to a toxicity series (0–50 μg/mL⁻¹) for the four chemicals in seven-day bioassays. Both microorganisms are tolerant of the inorganic salt, but growth inhibition was significant for all OT compounds, and especially large for TBT and TBTO. Although C. kessleri and E. gracilis are known to be tolerant towards metals and organic chemicals, the present results show that both are sensitive to organotin compounds: the inhibition of the growth was greater for C. kessleri. © 1998 John Wiley & Sons, Ltd.     

Review: structural diversity in organotin(IV) dithiocarboxylates and carboxylates

Organotin(IV) complexes are known for their outstanding structural diversity and applications. Organotin(IV) carboxylates and dithiocarboxylates form an important class of organotin(IV) compounds. The structural diversity of these compounds emanates from several features including flexibility in coordination geometries, coordination numbers, and versatility of the ligands to engage in different modes of chelation from monodentate to bidentate. Triorganotin(IV) complexes with various ligands mostly demonstrate tetrahedral or trigonal bipyramidal symmetry with some distortions, while diorganotin(IV) and chlorodiorganotin(IV) complexes have variation of geometries and coordination numbers. Some monoorganotin(IV) complexes have also been reported with pentagonal bipyramidal geometries.     

Organotin levels in the Ria Formosa lagoon,Portugal

Organotin concentrations were measured in water, sediments and clams (Ruditapes decussatus) from 11 sites in the Ria Formosa lagoon, Portugal, in 1992–93. Results showed a marked spatial pattern of tributyltin (TBT) and dibutyltin concentrations. The highest organotin concentrations were observed at Olhão (site 5), where the most important fishing harbour of the Southern coast of Portugal is located. Results indicated that fishing vessels, moored in the harbour at Olhão (site 5), were the major source of organotin contamination to the lagoon. No significant seasonal trend was observed, suggesting a continuous input of organotin compounds throughout the year. In several areas of the lagoon the TBT burdens in R. decussatus could have deleterious developmental effects. Copyright © 2002 John Wiley & Sons, Ltd.     

17O NMR spectra of some butyltin(IV) acetates

The ¹⁷O NMR spectra of ¹⁷O isotope‐enriched tributyltin(IV) acetate (1) and dibutyltin(IV) diacetate (2) were recorded in various solvents over wide temperature ranges. Only a single ¹⁷O signal was observed for both oxygen atoms of the —COOSn—groups under these experimental conditions, in both non‐coordinating and coordinating solvents. The ¹⁷O NMR spectra of tert‐butyl acetate (3) were obtained for comparison. Copyright © 2002 John Wiley & Sons, Ltd.