Imposex in Sea Snails,Caused by Organotin (Tributyltin and Triphenyltin) Pollution in Japan: a Survey

A country-wide survey and laboratory experiments on imposex (a superimposition of male sex organs on female sea snails) in Japanese sea snails were carried out: 38 species were observed to be affected by imposex. For the rock shell, Thais clavigera , the percentage occurrence of imposex was 100% at almost all sites surveyed. The degree of imposex seemed to be positively correlated with the concentrations of tributyltin (TBT) and triphenyltin (TPT) in the species. The results of laboratory experiments showed that imposex in T. clavigera was initiated and promoted by both TBT and TPT. Many oviduct-blocked individuals, which were thought to be sterile, were observed in T. clavigera at sites near marinas and harbours. The effects of organotin pollution on the population of T. clavigera were observed at the sites near marinas. From the results of the additional country-wide survey on imposex in T. clavigera during 1993–1995, serious organotin pollution and imposex symptoms in the species are still continuing in Japan. © 1997 by John Wiley & Sons, Ltd.     

Search for triorganotins along the Mar del Plata (Argentina) marine coast: finding of tributyltin in egg capsules of a snail Adelomelon brasiliana (Lamarck, 1822) population showing imposex effects

Cases of imposex were clearly identified in Adelomelon brasiliana living in the Mar del Plata (Argentina) coastal area; percentages as high as 50.0% were determined among the samples studied. These were the first reported cases of ocurrence of imposex in this type of gastropod. Since this is one of the known tributyltin (TBTs) effects, and no previous reports of determination of TBTs in gastropods eggs were found, methods were developed for the speciation and quantitative determination of organotins in A. brasiliana egg capsules. Determination of organotins in samples collected in the Mar del Plata area showed contents of tributyltin chloride (TBT) as high as 400 ng l^?1 in water and 6.50 µg g^?1 in sediments of areas of intensive boat traffic. The results showed the presence of TBT in the egg capsules of A. brasiliana at three different instars (range 0.264–1.86 µg per egg). As far as we know, this is the first report of the finding of TBT in gastropod egg capsules. Copyright © 2004 John Wiley & Sons, Ltd.     

Structural Relationships obtained from the Coordination of α‐Picolinamide to the (Iminodiacetato)copper(II) Chelate: Synthesis,Crystal Structure,and Properties of (α‐Picolinamide)(iminodiacetato)copper(II) Dihydrate

The stoichiometric reaction of copper(II) hydroxycarbonate, iminodiacetic acid (H₂IDA = HN(CH₂CO₂H)₂) and α‐picolinamide (pya) in water yields crystalline samples of (α‐picolinamide)(iminodiacetato)copper(II) dihydrate, [Cu(IDA)(pya)] · 2 H₂O ( 1 ). The compound was characterised by thermal (TG analysis with FT‐IR study of the evolved gasses), spectral (IR, electronic and ESR spectra), magnetic and single crystal X‐ray diffraction methods. It crystallises in the triclinic system, space group P1, a = 8.8737(4), b = 10.23203(5), c = 15.7167(11) Å, α = 77.61(1)°, β = 103.89(1)°, γ = 80.32(1)°, Z = 4, final R1 = 0.056. The asymmetric unit contains two crystallographic independent molecules but chemically very similar ones. The Cu^II atom exhibits a square base pyramidal coordination (type 4 + 1). pya acts as N,O‐bidentate ligand supplying two among the four closest donor atoms of the metal [averaged bond distances (Å): Cu–N = 1.982(2), Cu–O(amide) = 1.972(2)]. IDA plays a N,O,O′‐terdentate chelating role [averaged bond distances (Å): Cu–N = 2.004(3), Cu–O = 1.941(2) and Cu–O = 2.242(2)]. The coordinating behaviour of pya in 1 is discussed on the basis of its N,O‐bidentate chelating role and the preference of the ‘Cu‐iminodiacetato' moiety [Cu(IDA)] to link the N‐heterocyclic donor of pya in trans versus the Cu–N(IDA) bond. Consistently the ligand pya is able to impose a fac‐chelating configuration to IDA one around the copper(II) as previously has been reported to mixed‐ligand complexes having a 1/1/2 Cu^II/IDA/N(heterocyclic) donor ratio or a closely related 1/1/1/1 Cu^II/IDA/N(heterocyclic)/N(aliphatic) one.     

Spectroscopic,thermal and antimicrobial properties of the copper(II) complex of Schiff base derived from 2‐(salicylidene) aminopyridine

Schiff bases and their complex combinations with metallic ions represent a class of compounds with antimicrobial activity. A ligand was prepared by condensation of the salicylaldehyde with 2‐aminopyridine obtaining 2‐(salicylidene) aminopyridine (SB) with a high capacity for complexing Cu(II) ions. The new compound has been characterized by physical constants (melting point, solubility, stability) and the chemical structure was confirmed by elemental, spectral (IR, UV–visible, ¹H NMR and ¹³C‐NMR) and thermal analyses. The elemental analysis gives a coordination ratio of 1:2 metal:Schiff base. Lethal dose 50 (DL₅₀) values of new Schiff base and their complex with metallic ions were established. The antimicrobial activity of this complex was tested in comparison with the activity of the corresponding Schiff base on strains of Staphylococcus aureus, Bacillus cereus, Bacillus subtilis, Escherichia coli, Candida albicans, and Klebsiella. These were compared with the activity of the reference drugs (chloramphenicol, tetracycline, ofloxacin and nystatin) on the above‐mentioned strains. It has been established that all compounds tested were very active against both Gram‐positive and Gram‐negative bacteria. Copyright © 2012 John Wiley & Sons, Ltd.     

Study on the Bond Covalency and Bond Susceptibility in NdCr_(1-x)M_xO_3 (M=Mn, Fe, Co)

IntroductionNdCrl-.M.Os(M=Mn,Fe,Co)'-'haveanorthorhombicperovskite-typestrUcture,andareallp-typesendconductors.lnNdCr,-.Mn.O,'andNdCr,-.Fe.O,',theaverage(Cr,Mn)-Oand(Cr,Fe)-Obonddistancesandeffectivemagneticmomentincreasewiththeincreasingdopinglevel,indicatingthatMn3 andFe3 ionsareinhigh-spinstateswith(dE)'(dY)'and(dE)'(dY)'electronconfigurationsrespectively.However,forNdCr,x.Co.O,'atlowtemperatures,theaverage(Cr,Co)-Obonddistancesandeffectivemagneticmomentsdecrease,suggestingtha…     

Synthetic,structural and spectroscopic studies of copper(II) complexes derived from the combination of the succinamate(−1) ligand with aromatic N,N′-chelates

The use of succinamic acid (H₂sucm)/N,N′-chelate (2,2′-bipyridine, bpy; 4,4′-dimethyl-2,2′-bipyridine, dmbpy; 1,10-phenanthroline, phen) ‘ligand blends’ in CuX₂·yH₂O (X = NO₃, y = 3; X = Cl, y = 0) chemistry has yielded the new complexes [Cu₂(Hsucm)₃(bpy)₂](NO₃)·0.5MeOH (1·0.5MeOH), [Cu₂(Hsucm)(OH)Cl(bpy)₂](OH)·3.6H₂O (5·3.6H₂O) and [Cu₂(Hsucm)₂Cl₂(phen)₂] (6). The succinamate(−1) ion behaves as a carboxylate ligand and exists in two different coordination modes in the structures of the above complexes, i.e., the common syn, syn μ₂-κO:κO′ in 1, 5 and 6, and the μ₂-κ²O:κO′ in 1. The primary amide group of Hsucm⁻ remains uncoordinated and participates in intermolecular hydrogen bonding interactions leading to 1D, 2D and 3D networks. Characteristic IR bands of the complexes are discussed in terms of the known structures and the coordination modes of the Hsucm⁻ ligands.     

Spin Crossover,Polymorphism and Porosity to Liquid Solvent in Heteroleptic Iron(III) {Quinolylsalicylaldimine/Thiosemicarbazone‐Salicylaldimine} Complexes

Heteroleptic iron(III) complexes of formula [Fe(qsal)(thsa)]?solvent have been synthesized: [Fe(qsal)(thsa)]?0.4 BuOH ( 1 ), [Fe(qsal)(thsa)]?0.5 MeCN ( 2 ) and [Fe(qsal)(thsa)]?0.5 THF, ( 3 ). The latter two show partial solvent loss at room temperature to yield [Fe(qsal)(thsa)]?0.1 MeCN ( 2′ ) and [Fe(qsal)(thsa)]?0.1 THF ( 3′ ), respectively. This family maintains a structural integrity which is analogous over different degrees of solvation, a rare occurrence in discrete molecular species. Uniquely, removal of MeCN from compound 2 leads to retention of crystallinity yielding the isostructural, fully desolvated compound [Fe(qsal)(thsa)] ( 2′′ ) and a new high spin polymorph, 4 . To the best of our knowledge, this is the first compound that forms polymorphs through a desolvation process. The desolvated mixture, 2′′ and 4 , is porous and can reabsorb MeCN and give rise to 2′ again. This illustrates the reversible single‐crystal‐to‐single‐crystal transformation of two polymorphs back to a purely original phase, 2′′ + 4 ? 2′ . The structural, magnetic and M?ssbauer features of the various samples are described in terms of spin crossover.     

Common Features in the Crystal Structures of the Compounds Bis(dimethylstibanyl)oxane and ‐sulfane,and the Minerals Valentinite and Stibnite (Grauspießglanz)

Bis(dimethylstibanyl)oxane ( 1 ) and ‐sulfane ( 2 ), the two simplest organoelement species with an Sb–E–Sb fragment (E = O, S), were prepared by alkaline hydrolysis of bromodimethylstibane and by oxidation of tetramethyldistibane with sulfur [18], respectively. As shown by an x‐ray structure analysis of compound 1 (m. p. < –20 °C; P2₁2₁2₁, a = 675.9(2), b = 803.1(2), c = 1666.8(4) pm at –70 ± 2 °C; Z = 4; R1 = 0.042), the molecules (O–Sb 198.8 and 209.9 pm, Sb–O–Sb 123.0°) adopt a syn‐anti conformation in the solid state and are arranged in zigzag chains along [010] via weak intermolecular O‥Sb interactions (258.5 pm, Sb–O‥Sb 117.8°, O‥Sb–O 173.5°) making use, however, of only one Me₂Sb moiety. Primary and secondary bond lengths and angles agree very well with corresponding values published for valentinite, the orthorhombic modification of antimony(III) oxide [3]. Bis(dimethylstibanyl)sulfane ( 2 ) (m. p. 29 to 31 °C) crystallizes in the uncommon space group P6₅22 (a = 927.8(3), c = 1940.9(7) pm at –100 ± 2 °C; Z = 6; R1 = 0.021). Owing to coordination numbers of (1 + 1) and (2 + 2) for both Me₂Sb groups and the sulfur atom, respectively, molecules with an approximate syn‐syn conformation (S–Sb 249.8 pm, Sb–S–Sb 92.35°) build up a three‐dimensional net of double helices which are linked together by Sb‥S contacts (316.4 pm). These parameters shed more light onto the rather complicated structure and bonding situation in stibnite (antimony(III) sulfide [4]). The molecular packing of compound 2 is compared with the structures of relevant inorganic solids, especially with that of β‐quartz [37].     

Oxovanadium(IV) and ruthenium(II) carbonyl complexes of ONS‐donor ligands derived from dehydroacetic acid and dithiocarbazate: Synthesis,characterization, antioxidant activity,DNA binding and in vitro cytotoxicity

A series of new complexes of oxovanadium(IV) [VO(L)(B)] and ruthenium(II) [Ru(CO)(PPh₃)₂(L)] ( 1.1- 1.3,  2.1–2.3 ) (H₂L = dehydroacetic acid Schiff base of S‐methyldithiocarbazate, H₂smdha ( 1 ) or S‐benzyldithiocarbazate, H₂sbdha ( 2 ); B = 2,2′‐bipyridine (bpy) or 1,10‐phenanthroline (phen)) have been synthesized. The structure of these complexes was authenticated using elemental analyses and spectroscopic techniques, and their magnetic properties and electrochemical behaviour were studied. The molecular structures of oxovanadium(IV) complexes [VO(smdha)(bpy)]?CH₂Cl₂ ( 1.1 ) and [VO(sbdha)(phen)]?2H₂O ( 2.2 ) were confirmed using single‐crystal X‐ray crystallography. Analytical data showed that the ligands 1 and 2 are chelated to the metal centres in a bi‐negative tridentate fashion through azomethine N, thiol S and deprotonated hydroxyl group. The antioxidant activity of the synthesized compounds was tested against 2,2‐diphenyl‐1‐picrylhydrazyl) radical, which showed that the complexes demonstrate a better scavenging activity than their corresponding ligands. The cupric ion reducing antioxidant capacity method was also employed and the total equivalent antioxidant capacity values were found to be higher for the oxovandium(IV) complexes. DNA binding affinity of the compounds was determined using UV–visible and fluorescence spectra, revealing an intercalation binding mode. Higher cytotoxicity for the complexes compared to their ligands was found against human liver hepatocellular carcinoma (HepG2) and breast adenocarcinoma (MCF7) cell lines using MTT assay.     

Tautomerism,protonation regioselectivity of 2-pyrrolidone and its complexation with palladium(II): an insight from the viewpoint of quantum chemistry

It has been established (AM1, PM3, RHF/6-31G**, MP2/6-31G**//RHF/6-31G**) that in the gaseous phase and in aqueous solution, the most thermodynamically stable tautomer of 2-pyrrolidone is lactame. According to PM3 evaluations with an explicit accounting for aqueous medium, the state of tautomeric equilibrium serves as a prerequisite to participation of 2-pyrrolidone's lactime tautomer (pyrroline-2-ol) in complexation with palladium(II) in aqueous solution. 2-Pyrrolidone protonation in the gaseous phase and in aqueous medium has been shown to proceed via the oxygen atom, corresponding to expectations on mesomeric displacement of electron density in the amide fragment. The aqueous medium stabilizes 2-pyrrolidone's lactime tautomer to a greater extent than for lactame, and an O-protonated cyclic amide compared to an N-protonated one. The stereodirective character of palladium(II) complexation with chloride ion and pyrroline-2-ol has been explained. The initially formed tetragonal–pyramidal adduct with an axial organic ligand rearranges into a precursor of the cis product, an intermediate with an extra coordinated axial chlorine atom. The less thermodynamically stable cis isomer of [PdCl₂(pyrroline-2-ol)₂] appears because its precursor is a lower energy intermediate of associative nucleophilic substitution. At a supramolecular level, cis product is capable of being stabilized by means of intermolecular dipole–dipole association in a crystal.     

New di‐ and triorganotin(IV) carboxylates derived from a Schiff base: synthesis,characterization and in vitro antimicrobial activities

A new carboxylic acid, 2‐{[5‐(2‐nitrophenyl)furan‐2‐yl]methyleneamino}benzoic acid (HOBZ), has been produced by reacting 5‐(2‐nitrophenyl)furfural with 2‐aminobenzoic acid. Reactions of NaOBZ with organotin chlorides led to formation of [Me₃Sn(OBZ)] ( 1 ), [Bu₃Sn(OBZ)] ( 2 ), [Me₂Sn(OBZ)₂] ( 3 ) and [Bu₂Sn(OBZ)₂] ( 4 ). Complexes 1 , 2 , 3 , 4 have been characterized using elemental analyses and infrared, ¹H NMR, ¹³C NMR, ¹¹⁹Sn NMR and ¹¹⁹Sn Mössbauer spectroscopies. In the solid state, the OBZ ligands might coordinate to tin in an anisobidentate fashion via the carboxylate group. The in vitro antimicrobial activity of all compounds has been screened against the following fungi: Aspergillus niger, A. flavus, A. parasiticus, Penicillium citrinum, Candida dubliniensis, C. lusitaniae, C. albicans, C. tropicalis, C. parapsilosis and C. glabrata; and against the following bacteria: Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, Streptococcus sanguinis, Escherichia coli, Citrobacter frendii, Salmonella typhimurium and Pseudomonas aeruginosa. Complexes 2 and 4 exhibited higher biocide activity in comparison to 1 and 3 and to the control drugs nystatin and miconazole nitrate for the yeasts, and chloramphenicol and ampicillin for the bacteria. The biological activity of 2 was superior to that of 4 . In addition, the toxicity of HOBZ, NaOBz and 1 , 2 , 3 , 4 were determined using Chlorella vulgaris, revealing low toxicity of the complexes at MIC₅₀ concentrations. We also performed cell viability studies, using XTT assay, displaying no change in the mitochondrial function after 2–4 h of exposure of the microorganism to the complexes at MIC₅₀ concentrations. The butyl‐containing complexes 2 and 4 display greater lipophilicities than do the methyl analogues 1 and 3 , thereby endowing 2 and 4 with superior abilities to cross the microbe cell membrane, the possible mechanism of action. Copyright © 2015 John Wiley & Sons, Ltd.     

Design of C2-symmetric salen ligands and their Co(II)- or Yb(III)-complexes,and their role in the reversal of enantioselectivity in the asymmetric Henry reaction

Reversal of enantioselectivity in asymmetric Henry reactions was achieved with novel chiral C₂-symmetric salen ligands bearing morpholine moieties by changing the Lewis acid center from Co(II) to Yb(III). The possible transition state models were supported by mass spectrometry experiments.     

Poly(ester amide)s derived from glycine,even‐numbered diols,and dicarboxylic acids: Considerations on the packing

A new sequential poly(ester amide) derived from 1,12‐dodecanediol, sebacic acid, and glycine was synthesized and characterized. Its crystalline structure was studied with transmission electron microscopy and X‐ray diffraction. The results were compared with results for a related polymer, derived from glycine, 1,6‐hexanediol, and succinic acid, that produced a lower methylene/carbonyl ratio. The crystalline structures of both polymers corresponded to a periodic arrangement of two layers of hydrogen‐bonded molecular chains, whose polymethylene sequences mimicked the packing of polyethylene and the majority of polyesters. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1036–1045, 2001     

Bis(dichlorosilyl)methylamine – Synthesis,Crystal Structure,and Conformational Analysis in the Gas Phase

A straightforward preparation has been found for bis(dichlorosilyl)methylamine, (SiHCl₂)₂NMe ( 1 ), involving reaction between H₂NMe and an excess of SiHCl₃, dissolved either in pentane or THF at 253 K. 1 and a side‐product, 1,3,5‐trichloro‐2,4,6‐trimethylcyclotrisilazane, (–SiHCl–NMe–)₃ ( 2 ), were identified by elemental analysis, mass spectrometry and ¹H‐NMR‐spectroscopy. Some physical, NMR‐ and IR spectroscopical properties of 1 were determined. The molecular and crystal structure of 1 was investigated by single crystal X‐ray diffraction. Selected structural parameters: r(Si–N) 169.7(5), r(Si–Cl) 203.1(2)–204.4(2), r(C–N) 150.0(8) pm; a(SiNSi) 123.6(3), a(SiNC) 118.3(4)/118.0(4)°. Ab initio force field data and infrared intensities were calculated for four conformers of 1 . Comparison of the observed and calculated IR spectra favours the two structures found ab initio provided that their actual abundancies are different from those calculated.     

Synthesis,characterization, and crystal structure of [Ni(dap(A)<Subscript>2</Subscript>)]<Subscript>2</Subscript> (dap(AH)<Subscript>2</Subscript>: 2,6-diacetylpyridine bis(anthraniloyl hydrazone))—a molecule possessing an infinite double helical chain in the solid state

Anthraniloyl hydrazide (AH) contains two −NH₂ groups, one of them is attached to the aromatic ring and the other is the hydrazinic, −NH₂. It is found that only the later reacts with the carbonyl compounds to form Schiff bases, while the former remains inert. The reasons behind this difference in reactivity are analyzed on the basis of semi-empirical calculations, which show that the lone pair of the ring −NH₂ is considerably delocalized over the ring, resulting in an accumulation of a positive charge on this particular nitrogen. Ni(II) complex of 2,6-diacetylpyridine bis(anthraniloyl hydrazone) has been prepared and characterized by various physico-chemical methods. The structure of the complex was determined by X-ray crystallography. It was found that in the solid state, the compound exist as a dimer, and two coordinated ligand moieties form a double helix around the two metal ions. H-bonding then results in extension of double helix to an infinite chain.     

Substituent Effect on the Electronic Properties and Nature of the W≡C Bond in trans‐Cl(OC)(H3P)3W(≡C‐para‐C6H4X) (X = H,F, SiH3, CN,NO2, SiMe3, CMe3, NH2, NMe2) Complexes: A Computational Quantum Chemistry Study

In this investigation, we describe substituent effect on the dipole moment, ionization potential, electron affinity, structure, frontier orbitals energy, in the trans‐Cl(OC)(H₃P)₃W(≡C‐para‐C₆H₄X) (X = H, F, SiH₃, CN, NO₂, SiMe₃, CMe₃, NH₂, NMe₂) complexes using MPW1PW91 quantum chemical calculations. The nature of chemical bond between the [Cl(OC)(H₃P)₃W]⁻ and [C‐para‐C₆H₄X]⁺ fragments was illustrated with energy decomposition analysis (EDA). Percentage composition in terms of the defined groups of frontier orbitals for these complexes was inspected to investigate the character in metal–ligand bonds. Quantum theory of atoms in molecules (QTAIM) was used for illustration of metal–ligand bonds in these complexes.     

Structural data on the packing of poly(ester amide)s derived from glycine,hexanediol, and odd‐numbered dicarboxylic acids

The crystalline structure of a series of Poly(ester amide)s derived from glycine, hexanediol, and odd‐numbered dicarboxylic acids has been studied using transmission electron microscopy and X‐ray diffraction. Polymers crystallize in an orthorhombic lattice with parameters a = 4.80 Å, b = 22.68 Å, and c in the 45–55 Å interval, depending on the number of methylenes of the chemical repeat unit. The structure of the glutaric derivative can be interpreted as a singular packing of six hydrogen‐bonded sheets. Amide and ester interactions between neighboring layers favor two different sheet arrangements that give rise to the observed superstructure. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2521–2533, 1999