- Binuclear and mononuclear Cu(II) and Ni(II) complexes of tetra- and hexadentate ligands: Synthesis, antifungal activity, spectroscopic and thermal characterization
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Two tetradentate ligands, 1,2-bis(2-hydroxyethylthio)ethane S2O2 (L1) and N,N′-bis(2-hydoxypropyl)piperazine N2O2 (L2), were prepared by organization of some mononuclear complexes of Cu(II) and Ni(II). A new binuclear Schiff base ligand with a 1,4-dipropoxybutane spacer provided by the reaction of salicylaldehyde and 1,4-bis(3-aminopropoxy)butane served as an octadentate, N2O4 (L3) ligand, in designing some binuclear complexes with metal ions. All the ligands were characterized by elemental analyses, FTIR, 1H and 13C NMR and GC–MS. The complexes were characterized by elemental analyses, FTIR, thermal methods, electronic spectra, conductivity and magnetic measurements. The metal ions coordinate to the ligands with four donor atoms in square planar geometry. The thermal stabilities of the complexes were discussed in terms of metal ions and type of donor atoms. The complexes were characterized by electronic spectra and magnetic susceptibility measurements to establish the proposed four-coordinated square planar geometry. The TG chart indicates high thermal stability for complexes. The decomposition processes consisted of three stages: The first two stages involve the loss of water and chloride anions and the last stage indicates degradation of the organic ligands. The antifungal activity of the ligands and their complexes was tested against several fungal species: Aspergillus nigar, Aspergillus flavus and Candida albicans. The results show that complexes have significant antifungal activities compared to their parent ligands.
- Turkyilmaz, Murat
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- Synthesis, characterisation and ion-binding properties of oxathiacrown ethers appended to [Ru(bpy)2]2+. Selectivity towards Hg2+, Cd2+ and Pb2+
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A series of complexes with oxathiacrown ethers appended to a [Ru(bpy)2]2+ moiety have been synthesized and characterised using 1H NMR, 13C NMR, IR, electronic absorption and emission spectroscopies, mass spectrometry and elemental analyses. The complexes exhibit strong MLCT luminescence bands in the range 608-611 nm and one reversible metal centred oxidation potential in the range 1.00-1.02 V. Their selectivity and sensitivity towards Hg2+, Cd2+ and Pb2+ metal ions have been investigated using electronic absorption, luminescence, cyclic and differential pulse voltammetry titrations. Their responses towards selected cations and anions have also been investigated using electronic absorption and luminescence. While the complexes are selective towards Hg2+ and Cd2+ ions, none of them is selective towards Pb2+ ions. In particular, complex 2 gives a selective change in the UV/Vis absorbance with Hg2+ making it possible to detect mercury down to a detection limit of 68 ppm. The binding constants and limits of detection of the complexes have been calculated, with values ranging from 4.37 to 5.38 and 1.4 × 10-3 to 6.8 × 10-5 for log Ks and LOD respectively.
- Odhiambo, Ruth A.,Aluoch, Austin O.,Njenga, Lydia W.,Kagwanja, Stanley M.,Wandiga, Shem O.,Wendt, Ola F.
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- Unexpected Reaction Pathways Leading to Thiodiglycol during the Degradation of Long-Chain Sulfur Mustards
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Degradation of long-chain sulfur mustards with various commercial decontaminants unexpectedly forms thiodiglycol (TDG) through unreported reaction pathways. Chemical warfare agents (CWAs) degradation products have to be unambiguously related to their reference compounds in order to fulfill international verification protocols. Thus, the formation of TDG using water-based decontaminants introduces an uncertainty in the origin of this chemical that has been systematically used to unambiguously demonstrate the presence of yperite in environmental and biomedical samples. Therefore, these novel and unprecedented degradation pathways will result either in modifications of the international verification protocols for forensic purposes or in the exclusion of TDG as an exclusive marker of yperite.
- Gómez-Caballero, Esther,Martínez-álvarez, Roberto,Sierra, Miguel A.
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p. 12432 - 12439
(2018/10/15)
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- Synthesis of new β,β'-diketodithioethers via swern oxidation and study of their hydrazone formation rate
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The synthesis of β,β'-diketodithioethers 4b-j from corresponding β,β'-dihydroxydithioethers 3b-j was carried out by a Swern oxidation using DMSO-oxalyl chloride as oxidizing agent. β,β'- Dihydroxydithioethers 3b-j were prepared by the reaction of two molar equivalents of epoxides 1b-j with dimercaptoethane 2 in the presence of a saturated aqueous solution of potassium carbonate. The reactivity behavior of imine formation of the β,β'-diketodithioethers 4b-j by 2,4-dinitrophenylhydrazine was also investigated, and a mechanism was proposed by using molecular orbital (MO) calculations. To confirm the proposed mechanism, the role of the thia function to activate hydrazone formation by measuring HOMO-LUMO energy levels was also demonstrated.
- Seyedi, Seyed Mohammad,Sadeghian, Hamid,Safari, Zohreh
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experimental part
p. 2297 - 2306
(2010/03/31)
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- Synthesis and biological evaluation of some new thioether-ester crown ethers
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New thioether-ester crown ethers have been synthesized starting from oxalyl chloride and different β,β′-dihydroxydithioethers. The synthesized compounds are screened for their antibacterial activity. Among the macrocyclic thioether-esters (5a-j), only 5,12-di[(allyloxy)methyl]-1,4-dioxa-7, 10-dithiacyclododecane-2,3-dione (5e) and 5,12-di(isopropoxymethyl)-1,4-dioxa-7, 10-dithiacyclododecane-2,3-dione (5f) were effective inhibitors against Staphilococcus aureus methicillin resistance and Pseudomanas aeruginosa with an MIC value of 525 and 265 μM. Structures of the synthesized compounds have been confirmed by 1H NMR, 13C NMR, and MS spectral studies. Copyright Taylor & Francis Group, LLC.
- Seyedi, Seyed Mohammad,Sadeghian, Ali,Sadeghian, Hamid,Hazrathoseyni, Ayla,Sadeghian, Mohammad
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p. 265 - 272
(2007/10/03)
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- Hydrolysis and oxidation products of the chemical warfare agents 1,2-Bis[(2-chloroethyl)thio]ethane Q and 2,2′-Bis(2-chloroethylthio) diethyl ether T
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Syntheses of diols of structure [HOCH2CH2S] 2(CH2)n in 86-95% yield from the sodium salt of 2-mercaptoethanol and Br(CH2)nBr (n = 1 to 5) or in 60-90% yield from 2-chloroethanol and NaS(CH2)nSNa (n = 2 to 5) are described. The diol [HOCH2CH2SCH 2CH2]2O was prepared in 82% yield from the sodium salt of 2-mercaptoethanol and [ClCH2CH2] 2O, and in 88% yield from 2-chloroethanol and [HSCH 2CH2]2O. Mono- and bis-sulfoxides and bis-sulfones of these species were prepared in generally high yield by treatment with an equivalent of KIO4 in aqueous methanol, two equivalents of NaIO4 in aqueous methanol, or four equivalents of H2O2 in trifluoroacetic acid respectively. The compounds are important analytical standards for investigating the fate of the chemical warfare agents sesquimustard Q and oxygen mustard T in environmental samples.
- Timperley, Christopher M.,Black, Robin M.,Bird, Michael,Holden, Ian,Mundy, Joanna L.,Read, Robert W.
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p. 2027 - 2046
(2007/10/03)
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- Synthesis of certain multidentate benzimidazole-derived ligands
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Synthetic procedures are described for obtaining various multidentate ligands incorporating benzimidazole moieties.The benzimidazoles were obtained by the condensation of acids with o-phenylenediamines.Syntheses are reported for N,N-bis(1-methylbenzimidazol-2-ylmethyl)amine (2), N,N'-bis(1-methylbenzimidazol-2-ylethyl)ethylenediamine (5), N,N,N',N'-tetrakis(benzimidazol-2-ylmethyl)-1,2-diaminocyclohexane (6), N,N,N',N'-tetrakis(4-methylbenzimidazol-2-ylmethyl)-1,2-diaminocyclohexane (7), HOOC-(CH2)m-S-CH2-CH2-S-(CH2)n-S-Ch2-CH2-S-(CH2)m-COOH , BzIm-(CH2)m-S-CH2-CH2-S-(CH2)n-S-CH2-CH2-S-(CH2)m-BzIm , HOOC-CH2-S-(CH2-CH2-S)4-CH2-COOH (15) and BzIm-CH2-S-(CH2-CH2-S)4-CH2-BzIm (16).
- Sivagnanam, Usha,Pandiyan, Thangarasu,Palaniandavar, Mallayan
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p. 572 - 576
(2007/10/02)
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- THE CHEMISTRY OF 1,1'-THIOBIS(2-CHLOROETHANE) (SULPHUR MUSTARD) PART I: SOME SIMPLE DERIVATIVES
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Some derivatives of 1,1'-thiobis(2-chloroethane) (sulphur mustard) have been synthesized for use as reference compounds in a wide range of studies embracing analysis, metabolism, environmental degradation and decontamination.Compounds include products formed by hydrolysis, substitution and elimination reactions and their oxidised sulphoxide and sulphone analogues.A comprehensive series of methylthio, methylsulphinyl and methylsulphonyl derivatives has been synthesised in support of metabolic studies. Key words: Thiobis(2-chloroethane) and derivatives; analysis; metabolism; environmental degradation; decontamination
- Black, R. M.,Brewster, K.,Harrison, J. M.,Stansfield, N.
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- Crown Thioether Chemistry: Structural and Conformational Studies of Tetrathia-12-crown-4, Pentathia-15-crown-5, and Hexathia-18-crown-6. Implications for Ligand Design
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Tetrathia-12-crown-4 (12S4) in the solid state adopts a square conformation with the sulfur atoms at the corners, to yield a structure derived from fusion at the terminal S atoms of two "bracket" units. This macrocycle crystallizes in the monoclinic system, space group Cc, with a = 13.028(7) Angstroem, b = 12.884(5) Angstroem, c = 14.493(7), (β = 108.18(4) deg, and Z = 8.Pentathia-15-crown-5 (15S5) assumes an irregular conformation generated from two bracket units by fusion at one S atom and connection of the remaining two terminal S atoms by a -CH2CH2- linkage.This crown thioether also crystallizes in the monoclinic system, space group P21/n, with a = 16.444(3) Angstroem, b = 5.432(1) Angstroem, c = 18.255(3) Angstroem, β = 115.58(1) deg, and Z = 4.Hexathia-18-crown-6 (18S6) adopts a conformation produced by connection of two bracket units by two -CH2CH2- linkages.It crystallizes in the orthorhombic system, space group Fdd/2, with a = 20.466(1) Angstroem, b = 32.222(3) Angstroem, c = 5.213(4) Angstroem, and Z = 8.Analysis of these structures reveals a pronounced preference for gauche placement at C-S bonds.This preference causes the ubiquity of bracket units and contrasts with the antipathy to gauche placement of the C-O bonds in oxa-crown ethers.This marked difference derives from the difference in C-E bond lenghts, which changes nonbonded 1,4-interactions in both C-C-E-C and E-C-C-E fragments.
- Wolf, Robert E.,Hartman, JudithAnn R.,Storey, John M. E.,Foxman, Bruce M.,Cooper, Stephen R.
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p. 4328 - 4335
(2007/10/02)
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- Synthesis of SRS-active compounds
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A chemical synthesis of an SRS-A active compound from the reaction product of 1-halo-2-octyne and the ether of 2-penten-4-yn-1-ol including intermediates in the synthesis, some of which being antagonists of SRS-A useful for treating allergic reactions.
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