Thiocarboxylate Research Articles

Anomalous Behavior of the Amides of Benzo‐ and Dibenzocrown Thiocarboxylic Acids under the Conditions of Methylation.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Synthesis,Characterization and Evaluation of the Anticancer and Antimicrobial Activities of Some Novel Benzazole and Benzazine Derivatives

The present study was designed to synthesize and develop new useful lead compounds (some novel benzazole and benzazine derivatives ) of simple structure , exhibiting optimal in vitro anticancer and antimicrobial potency. Phenylenediamine derivative 1 was condensed with dithiocarboxylic acid derivatives 2 and produced benzimidazole derivative 4. The benzotriazepines 8 and 10 were formed by the reaction of 1 with dicarbonyl derivatives followed by intermolecular coupling reaction. The synthesis of benzotriazine12, benzotriazole 14,17, benzimidazole16 and benzothiadiazine 19 from compound 1 was also described. The Synthesized Compounds were characterized by Spectral Studies like IR, H1 – NMR and Analysis Spectra .The title compounds were screened for their possible In vitro anticancer and antimicrobial activities. Among the synthesized compounds, some have shown promisingly remarkable activities against different cancer cell lines (MCF-7 human breast cancer cells, HepG2 human hepatocarcinoma cells and PC3 human prostate cancer cells)and moderate to high antibacterial and antifungal activities. The obtained results showed that the most active compounds could be useful as a template for future design, modification and investigation to produce more active analogs.

Unsaturated sulfur compounds from reactions of lithiated methylazines with carbon disulfide and electrophiles

2-Methylpyridine (1a), 2,6-dimethylpyridine (1b), 2-methylpyrazine (1c) and 2-methylquinoline (1d) were treated with lithium diisopropylamide (LDA) in THF at low temperature followed by carbon disulfide to give the dianion (5). Reactions of dianion (5) with iodomethane, 1,2-dibromoethane, ethyl chloroacetate, α -chloroacetonitrile or phenacyl bromide gave 6a–c, 6e, 9, 10, 11, 12 and 13, respectively. Reactions of dianion (5) with 1,2-dibromoethene gave the dithiocarboxylic acids (14a–c) rather than a dithiolene, and reaction of dianion (5a) with aqueous ammonium persulfate gave 15. Treatment of 2-methylpyridine (1a) with lithium diisopropylamide (LDA) and 2-bromopyridine afforded tetra-2-pyridylmethane (18) as the main product.

Preparation of Thiocarboxylate, Thiocarbamate and Xanthate Complexes of Pentacoordinate Nickel(II): Insertion of Heterocumulenes Into Nickel(II) Hydroxido Complexes

AbstractThe hydroxido complexes [Ni(N3‐mc)(μ‐OH)]2[PF6]2 [N3‐mc = 2,4,4‐trimethyl‐1,5,9‐triazacyclododec‐1‐ene (N3‐mc1) or 2,4,4,9‐tetramethyl‐1,5,9‐triazacyclododec‐1‐ene (N3‐mc2)] react in the presence of alcohols with CS2 or PhNCS to yield xanthate [(N3‐mc)Ni{S2C(OR′)}][PF6] or O‐alkyl N‐phenylthiocarbamate [(N3‐mc)Ni{PhNC(OR′)S}][PF6] complexes; these compounds represent the first examples of N,S‐chelating thiocarbamates bound to nickel(II). The reactions of [Ni(N3‐mc)(μ‐OH)]2[PF6]2 with thiocarboxylic acids yield the corresponding thiocarboxylate derivatives [(N3‐mc)Ni{SC(O)R′}][PF6]. These paramagnetic nickel(II) complexes were characterized by both one‐ and two‐dimensional (COSY) 1H NMR spectroscopic techniques. The crystal structures of [(N3‐mc2)Ni(S2COCH3)][PF6] (2), [(N3mc2)Ni{PhNC(OCH2CH3)S}][PF6] (8), [(N3‐mc2)Ni{SC(O)CH3}][PF6] (10) and [(N3‐mc1)Ni{SC(O)Ph}][PF6] (11) were determined. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Chlorodifluorothioacetic Acid, CF2ClC(O)SH: Synthesis, Characterization, X‐ray Structure and Conformational Properties

AbstractChlorodifluoroacetic anhydride, [CF2ClC(O)]2O, and chlorodifluoroacetyl chloride, CF2ClC(O)Cl, react with hydrogen sulfide to yield chlorodifluorothioacetic acid, CF2ClC(O)SH. This novel thiocarboxylic acid has been obtained in pure form and characterized by NMR, IR and Raman spectroscopy. By extrapolation of the vapour pressure curve, log p = 6.102–2068/T (p [bar], T [K]), the boiling point was determined to be 66(1) °C. The melting point of the pure substance is –83(2) °C. The conformational properties of the gas‐phase molecule have been studied by vibrational spectroscopy [IR (vapour), Raman (liquid)] and quantum chemical calculations [B3LYP and MP2 methods with 6‐311++G(d,p) and 6‐311++G(3df,2p) basis sets]. The most stable form has C1 symmetry with a synperiplanar (syn) orientation of the C=O double bond with respect to the S–H single bond whereas in the chlorodifluoroacetyl group the gauche orientation of the ClC–C=O moiety is preferred (gauche‐syn form). The analysis of the IR spectrum of gaseous CF2ClC(O)SH suggests the presence of two other conformations in equilibrium at room temperature. These forms have been fully characterized by high‐level quantum chemical calculations. The structure of a single crystal, grown by a miniature zone‐melting procedure using focused infrared laser radiation, was determined by X‐ray diffraction analysis at low temperature. The crystalline solid [monoclinic, space group C2/c, a = 17.6165(14), b = 5.8848(5), c = 11.0877(9) Å, β = 113.5330(11)°] consists exclusively of molecules adopting the gauche‐syn conformation. These molecules associate, forming pairs of cyclic dimers in the crystal through S–H···O=C hydrogen bonds.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Synthesis of stannic(IV) complexes: Their structural elucidation in solid and solution state and antimicrobial activity

AbstractA series of organotin(IV) thiocarboxylates have been synthesized with the general formula R2SnL2 and R3SnL (R = Ph2(I), Me3(II), n‐Bu3(III), Ph3(IV), Cy3(V), Me2(VI), n‐Bu2(VII), and L = piperidine‐1‐thiocarboxylic acid) in anhydrous toluene under the reflux conditions. The complexes were characterized by microanalysis, IR, 1H and 13C NMR, mass spectrometry, and XRD. NMR data revealed that thiocarboxylic acid acts as bidentate, and complexes exhibit the four‐coordinated geometry in solution state. In solid state, diorganotin complexes exhibit the hexa‐coordinated geometry whereas the triorganotin(IV) compounds show the five‐coordinated geometry. These complexes were also tested for their antimicrobial activity along with the ligand against different animals, plant pathogens, and Artemia salina. All complexes with few exceptions show high activity as compared to the ligand. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:664–674, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20380

Siderophores in Fluorescent Pseudomonads: New Tricks from an Old Dog

Iron is an essential nutrient for almost all bacteria; however, at neutral pH its bioavailability is limited. Siderophores are iron-binding compounds of low molecular weight that enable the microorganisms that produce them to obtain the necessary iron from the environment. Fluorescent pseudomonads include those that are plant growth promoting, human and plant pathogens, as well as bacteria involved in the biodegradation of xenobiotics. Although pyoverdine is the main siderophore produced by different fluorescent pseudomonads, other siderophores produced by fluorescent pseudomonads include pyochelin, (thio)quinolobactin and pyridine-2, 6-bis thiocarboxylic acid. Research on siderophores continues to reveal new information on their regulation, biosynthesis, function and properties. In this review, we focus on recent advances in the field, particularly on newly characterized siderophores produced by fluorescent pseudomonads and their biotechnological potential.

Sum Frequency Generation Imaging of Microcontact-Printed Monolayers Derived from Aliphatic Dithiocarboxylic Acids: Contrast Based on Terminal-Group Orientation

The results of imaging μCP printed monolayers using sum frequency generation vibrational spectroscopy are presented, where the image contrast is based on the orientation of the terminal methyl groups. The printed regions contain thiols with 16 carbon atoms (even), and the backfilled regions contain 17 carbon atoms (odd). In the odd/even effect, the terminal group alternates its orientation as the number methylene group changes from even to odd. On the basis of this result, SFG imaging microscopy (SFGIM) is used to image the C16 and C17 regions where the difference is based on the orientation of the terminal methyl group. Furthermore, we compared the patterns formed by C16/C17 n-alkanethiols and C16/C17 aliphatic dithiocarboxylic acids. We find that the dithiocarboxylic acids form much-better patterns where the degree of mixing between the stamped and backfilled regions is reduced compared to the n-alkanethiols. Furthermore, this results shows that SFGIM is a useful technique to visualize monolayers based not only on the chemical functionality but also on the surface orientation of the adsorbates.

Zinc, Cadmium and Mercury Dithiocarboxylates: Synthesis, Characterization, Structure and Their Transformation to Metal Sulfide Nanoparticles

AbstractReactions of M(OAc)2·nH2O and M(OAc)2(tmeda) with dithiocarboxylic acids gave [M(S2CTol)2]n (1) (M = Zn or Cd; Tol = C6H4Me‐4) and [M(S2CAr)2(tmeda)] (3) (M = Zn, Cd, Hg; Ar = Ph or Tol), respectively, in high yields as deep‐colored crystalline solids. The former are soluble in pyridine to give pyridine adducts [M(S2CTol)2(py)] (2). These complexes were characterized by elemental analysis, UV/Vis and NMR (1H, 13C) spectroscopy. The absorptions in the electronic spectra have been assigned to ligand‐to‐ligand charge‐transfer transitions. The crystal and molecular structures of the monomeric species [Zn(S2CTol)2(py)] (2), [Zn(S2CPh)2(tmeda)] (3a), [Zn(S2CTol)2(tmeda)] (3b) and [Cd(S2CTol)2(tmeda)] (3d) have been established by X‐ray crystallography. In [Zn(S2CTol)2(py)], chelating dithiocarboxylate ligands and pyridine define a coordination geometry intermediate between square pyramidal and trigonal bipyramidal. In each of 3a and 3b, tetrahedral N2S2 coordination geometries are found as the dithiocarboxylate ligands are effectively monodentate; evidence for the greater coordination potential is found for –S2CTol over –S2CPh. Chelating dithiocarboxylate ligands in [Cd(S2CTol)2(tmeda)] (3d) lead to an octahedral geometry. Thermal behavior has been studied by thermogravimetric analysis. The [M(S2CAr)2(tmeda)] complexes underwent a three‐step decomposition. Pyrolysis in the temperature range 300–500 °C and solvothermal decomposition in ethylenediamine and hexadecylamine (HDA) gave metal sulfide nanoparticles. The MS (M = Zn, Cd, Hg) nanoparticles were characterized by XRD, EDAX, absorption/emission spectroscopy and electron microscopy (TEM). Solvothermal decomposition gave hexagonal phases of nanoparticles whereas heating in a furnace gave cubic ZnS and HgS, and hexagonal CdS. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Anomalous behavior of the amides of benzo-and dibenzocrown thiocarboxylic acids under the conditions of methylation

During the reaction of the amides of benzo-and dibenzocrown thiocarboxylic acids with methyl iodide in the presence of potassium hydroxide they exhibit anomalous behavior leading to the nitriles of benzo-and dibenzocrown carboxylic acids. The nitriles of benzo-15-crown-5-, benzo-12-crown-4-, and dibenzo-18-crown-6-4′-carboxylic acids and the dinitriles of dibenzo-18-crown-6-and dibenzo-24-8-4′,4″(5″)-dicarboxylic acids were obtained.

Gas-phase acidities of thiocarboxylic acids

The gas-phase acidity of thioacetic acid, determined using ion–molecule equilibrium reactions, was found to be Δ G acid = 329.0 ± 1.5 kcal mol −1. The gas-phase acidity of thiobenzoic acid was determined by ion–molecule bracketting reactions to be Δ G acid = 323 ± 5 kcal mol −1. Gas-phase acidities of these compounds, as well as of thioformic acid, were calculated; our calculations and experiments are in good agreement. The calculated value of the enthalpy of deprotonation of thioformic acid is consistent with previously published computational results.

Water‐soluble metalworking fluid additives derived from the derivatives of 3‐mercaptopropionic acid

AbstractA number of derivatives of thiocarboxylic acid were prepared from the reaction of 3‐mercaptopropionic acid and alkyl halides, and screened for anti‐rust properties in water‐soluble metalworking fluids. Aqueous metalworking fluids containing octylthiopropionic acid or hexylthioacetic acid showed excellent anti‐rust properties for water‐soluble metalworking fluids.

Synthesis and spectral characterization of novel oxo-bridged, thiocarboxylato complexes of chromium(III)

A variety of novel oxo-bridged trinuclear mixed-ligand complexes of chromium(III) were synthesized by substitution reactions of acetate ions from their respective acetate complexes. The isolated products of the types [Cr3O(OAc)3(OOCR] 3 + and [Cr3O(SOCPh)3(OOCR)3]+ (R = C13H27, C15H31 or C17H35) are mixed-ligand chromium(III) complexes with straight-chain carboxylic and thiocarboxylic acids. These were characterized by elemental analyses, spectral (infrared, electronic, FAB mass, and powder XRD) studies, molar conductances, and magnetic susceptibility measurements. The IR spectra suggested the bridging nature of the carboxylate and thiocarboxylate anions along with v as (Cr3O) vibrations in the complexes. The trinuclear nature of the complexes was assessed from the FAB mass data. Electronic absorption spectra and magnetic moment data were in favor of an octahedral environment around chromium(III), which was supported by their powder X-ray diffraction data. Conductance measurements indicated that the complexes were 1: 1 electrolytes in nitrobenzene. Structures of the complexes were established on the basis of spectral and other physicochemical studies.

The role of the siderophore pyridine-2,6-bis (thiocarboxylic acid) (PDTC) in zinc utilization by Pseudomonas putida DSM 3601

Previous work had suggested that in addition to serving the function of a siderophore, pyridine-2,6-bis(thiocarboxylic acid) (PDTC) may also provide producing organisms with the ability to assimilate other divalent transition metals. This was tested further by examining regulation of siderophore production, expression of pdt genes, and growth in response to added zinc. In media containing 10-50 microM ZnCl2, the production of PDTC was found to be differentially repressed, as compared with the production of pyoverdine. The expression of PdtK, the outer membrane receptor involved in PDTC transport, was also reduced in response to added zinc whereas other iron-regulated outer membrane proteins were not. Expression of a chromosomal pdtI: xylE fusion was repressed to a similar extent in response to zinc or iron. Mutants that cannot produce PDTC did not show a growth enhancement with micromolar concentrations of zinc as seen in the wild type strain. The phenotype of the mutant strains was suppressed by the addition of PDTC. The outer membrane receptor and inner membrane permease components of PDTC utilization were necessary for relief of chelator (1,10-phenanthroline)-induced growth inhibition by Zn:PDTC. Iron uptake from 55Fe:PDTC was not affected by a 32-fold molar excess of Zn:PDTC. The data indicate that zinc present as Zn:PDTC can be utilized by strains possessing PDTC utilization functions but that transport is much less efficient than for Fe:PDTC.

Ab initio computational modeling on the tautomerism of monochalcogenocarboxylic acids CH3C(O)XH (X = S, Se, and Te) in the polar and aprotic solution

AbstractComputational modeling by an ab initio molecular orbital method (HF and MP2) with the 6‐311+G(d,p) and 6‐311++G(2df,2pd) basis sets on the tautomerism of three monochalcogenocarboxylic acids CH3C(O)XH (X = S, Se, and Te) in the polar and aprotic solution tetrahydrofuran (THF) was undertaken using the combined supramolecular/continuum method, in which CH3OCH3 was considered as a realistic model for THF in the supermolecule. Our calculations showed that the tautomerism involving CH3OCH3 not only gives the preference of the enol form CH3C(X)OH (X = S, Se, and Te) in the tautomeric equilibrium, but also significantly lowers the tautomeric barriers by >34 kJ/mol in THF solution. These results support the experiments of Kato and coworkers, in contrast with earlier Delaere et al.'s theoretical prediction for the tautomeric barrier of thioformic acid HC(O)SH…O(CH3)2, in which the barrier is increased by ∼6 kJ/mol relative to reactants complex because of the constraint in locating the tautomeric transition structure. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007

Thioquinolobactin, a Pseudomonas siderophore with antifungal and anti‐Pythium activity

Under conditions of iron limitation Pseudomonas fluorescens ATCC 17400 produces two siderophores, pyoverdine, and a second siderophore quinolobactin, which itself results from the hydrolysis of the unstable molecule 8-hydroxy-4-methoxy-2-quinoline thiocarboxylic acid (thioquinolobactin). Pseudomonas fluorescens ATCC 17400 also displays a strong in vitro antagonism against the Oomycete Pythium, which is repressed by iron, suggesting the involvement of a siderophore(s). While a pyoverdine-negative mutant retains most of its antagonism, a thioquinolobactin-negative mutant only slowed-down Pythium growth, and a double pyoverdine-, thioquinolobactin-negative mutant, which does not produce any siderophore, totally lost its antagonism against Pythium. The siderophore thioquinolobactin could be purified and identified from spent medium and showed anti-Pythium activity, but it was quickly hydrolysed to quinolobactin, which we showed has no antimicrobial activity. Analysis of antagonism-affected transposon mutants revealed that genes involved in haem biosynthesis and sulfur assimilation are important for the production of thioquinolobactin and the expression of antagonism.

Identification and characterization of Pseudomonas membrane transporters necessary for utilization of the siderophore pyridine-2,6-bis(thiocarboxylic acid) (PDTC)

The compound pyridine-2,6-bis(thiocarboxylic acid) (PDTC) is known to be produced and excreted by three strains of Pseudomonas. Its reactivity includes the complete dechlorination of the environmental contaminant carbon tetrachloride. PDTC functions as a siderophore; however, roles as a ferric reductant and antimicrobial agent have also been proposed. PDTC function and regulation were further explored by characterizing the phenotypes of mutants in predicted membrane transporter genes. The functions of a predicted outer-membrane transporter (PdtK) and a predicted inner-membrane permease (PdtE) were examined in Pseudomonas putida DSM 3601. Uptake of iron from (55)Fe(III):PDTC, and bioutilization of PDTC in a chelated medium, were dependent upon PdtK and PdtE. Another strain of P. putida (KT2440), which lacks pdt orthologues, showed growth inhibition by PDTC that could be relieved by introducing a plasmid containing pdtKCPE. Transcriptional activation in response to exogenously added PDTC (25 muM) was unaltered by the pdtK or pdtE mutations; each mutant showed activation of a pdt transcriptional reporter, indistinguishable from an isogenic PDTC utilization-proficient strain. The data demonstrate that PdtK and PdtE constitute a bipartite outer-membrane/inner-membrane transport system for iron acquisition from Fe(III):PDTC. Disruptions in this portion of the P. putida DSM 3601 pdt gene cluster do not abolish PDTC-dependent transcriptional signalling.

Transcriptional Regulation of the pdt Gene Cluster of Pseudomonas stutzeri KC Involves an AraC/XylS Family Transcriptional Activator (PdtC) and the Cognate Siderophore Pyridine-2,6-Bis(Thiocarboxylic Acid)

In order to gain an understanding of the molecular mechanisms dictating production of the siderophore and dechlorination agent pyridine-2,6-bis(thiocarboxylic acid) (PDTC), we have begun characterization of a gene found in the pdt gene cluster of Pseudomonas stutzeri KC predicted to have a regulatory role. That gene product is an AraC family transcriptional activator, PdtC. Quantitative reverse transcription-PCR and expression of transcriptional reporter fusions were used to assess a role for pdtC in the transcription of pdt genes. PdtC and an upstream, promoter-proximal DNA segment were required for wild-type levels of expression from the promoter of a predicted biosynthesis operon (P(pdtF)). At least two other transcriptional units within the pdt cluster were also dependent upon pdtC for expression at wild-type levels. The use of a heterologous, Pseudomonas putida host demonstrated that pdtC and an exogenously added siderophore were necessary and sufficient for expression from the pdtF promoter, i.e., none of the PDTC utilization genes within the pdt cluster were required for transcriptional signaling. Tests using the promoter of the pdtC gene in transcriptional reporter fusions indicated siderophore-dependent negative autoregulation similar to that seen with other AraC-type regulators of siderophore biosynthesis and utilization genes. The data increase the repertoire of siderophore systems known to be regulated by this type of transcriptional activator and have implications for PDTC signaling.

Thiocarboxylic Acids and Derivatives, α‐Substituted Sulfur Ylides

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Pyridine-2,6-bis(thiocarboxylic acid) Produced by Pseudomonas stutzeri KC Reduces Chromium(VI) and Precipitates Mercury, Cadmium, Lead and Arsenic

Interactions of the Pseudomonas stutzeri KC siderophore pyridine-2,6-bis(thiocarboxylic acid) (pdtc) with chromium(VI), mercury(II), cadmium(II), lead(II), and arsenic(III) are described. Pdtc was found to reduce Cr(VI) to Cr(III) in both bacterial cultures and in abiotic reactions with chemically synthesized pdtc. Cr(III) subsequently formed complexes with pdtc and pdtc hydrolysis products, and their presence was confirmed using electrospray ionization-mass spectrometry (ESI-MS). Cr(III):pdtc complexes were found to slowly release Cr(III) as chromium sulfide and possibly Cr(III) oxides. Pdtc also formed poorly soluble complexes with Hg, Cd, Pb, and As(III). Hydrolysis of those complexes led to the formation of their respective metal sulfides as confirmed by energy dispersive X-ray spectroscopy (EDS) elemental analysis. The pdtc-producing strain P. stutzeri KC showed higher tolerance to most of these metals as compared to a pdtc-negative mutant. A novel role of pdtc is postulated as its involvement in providing an extracellular pool of thiols that are used for redox processes in detoxification of the bacterial extracellular environment. These redox processes can be mediated by transition metal:pdtc complexes.