Mono Anions Research Articles

Synthesis, characterization and catalytic properties of ruthenium(III) complexes containing 4-hydroxy-3-( p -X-phenylazo)-benzopyrane-2-one

Ruthenium(III) complexes of the type trans-[Ru(L)2(AsPh3)2]Cl (L = mono anions of 4-hydroxy-3-(p-X-phenylazo)-benzopyrane-2-one derivatives (For L1, X = H; L2, X = CH3; L3, X = Cl; and L4, X = NO2; AsPh3 = triphenylarsine) have been synthesized and characterized by elemental analysis, spectroscopic (IR, UV-VIS and ESR), magnetic and cyclic voltammetric techniques. The mechanism and the catalytic oxidation of benzyl alcohol, cyclohexanol and cinnamyl alcohol by trans-[Ru(L1)2(AsPh3)2]Cl with hydrogen peroxide as co-oxidant were described.

Fluorescent Receptor Bearing Two 2-Aminobenzimidazole Moieties for Dicarboxylates

A new neutral receptor containing 2-aminobenzimidazole moieties was synthesized. The binding properties of the host 1 toward dicarboxylates and mono anions have been examined by using fluorescence spectrometry. The host 1 effectively recognized malonate, succinate, glutarate, adipate, and pimelate with 1:1 binding through hydrogen bonding interactions, and it also recognized acetate with 1:1 binding.

Structural signatures of the complex formed between 3-nitro-4-hydroxybenzoate and the Zn(II)-substituted R(6) insulin hexamer.

3-Nitro-4-hydroxybenzoate (3N4H) is a probe of the structure and dynamics of the metal-centered His B10 assembly sites of the insulin hexamer. Each His B10 site consists of a approximately 12 A-long cavity situated on the threefold symmetry axis. These sites play an important role in the storage and release of insulin in vivo. The allosteric behavior of the insulin hexamer is modulated by ligand binding to the His B10 zinc sites and to the phenolic pockets. Binding to these sites drives transitions among three allosteric states, designated T(6), T(3)R(3), and R(6). Although a wide variety of mono anions bind to the His B10 zinc sites of R(3), X-ray structures of ligands complexed to this site exist only for H(2)O, Cl(-), and SCN(-). This work combines one- and two-dimensional (1)H NMR and UV-Vis absorbance studies of the structure and dynamics of the 3N4H complex, which establish the following: (1). relative to the NMR time scale, 3N4H exchange between free and bound states is slow, while flipping among three equivalent orientations about the site threefold axis is fast; (2). binding of 3N4H perturbs resonances within the His B10 zinc site and generates NOEs between ligand resonances and the insulin C-alpha and side chain resonances of ValB2, AsnB3, LeuB6, and CysB7; and (3).3N4H exchange for other ligands is limited by a protein conformational transition. These results are consistent with coordination of the 3N4H carboxylate to the His B10 zinc ion and van der Waals interactions with Val B2, Asn B3, Leu B6, and Cys A7.

Isomorphous phosphonoacetic acid salts with magnesium(II), manganese(II), cobalt(II), zinc(II) and copper(II)

Abstract All crystals of the title compounds, with general formula M2+(C2H4O5P–)2(H2O)2, (MAP), are isomorphous and crystallize in the space group P1̅ with Z = 2. The two crystallographically independent M2+ cations are situated on a center of symmetry and are octahedrally coordinated by two phosphonate monoanions and two water molecules. In the case of Cu2+ cation, Jahn-Teller effect causes strong extension of two Cu—O bonds. The mono anions coordinate the metal ions by one carboxylic and one phosphonate oxygen atom, which is facilitated by their specific overall conformation. In each monoanion, one of the phosphonate O atoms is nearly antiperiplanar ap to the carboxylic C atom, and the remaining phosphonate O atoms are nearly gauche (+sc and –sc) with respect to the mentioned C atom. The carboxylic O atoms are in positions close to +sc and –ac in relation to the phosphonate P atom. The complex molecules form well separated layers in all MAP compounds. The phosphonate and carboxylic groups act as donors in medium strong and weak intermolecular O—H...O hydrogen bonding and, as acceptors, in C—H...O hydrogen interactions in all structures. Additionally both crystallographically independent water molecules are donors of weak hydrogen bonding to phosphonate oxygen atoms from adjacent complex molecules.

Protonation-induced rearrangements in Langmuir films and redox properties of Langmuir–Blodgett films of 2-( n-alkyl)fulleropyrrolidines

The effect of protonation of the pyrrolidine ring nitrogen of 2-( n-alkyl)fulleropyrrolidines, C 60pyr–C m ( m=4, 6, 8, 10 and 12), on the properties of the Langmuir and Langmuir–Blodgett (LB) films was investigated. The isotherms of both surface pressure ( π) and surface potential change (Δ V) versus area per molecule ( A) for the Langmuir films of C 60pyr–C m were determined simultaneously. It was found that the longer the alkyl chain of the fulleropyrrolidine the larger is the film compressibility, κ, i.e., κ(C 60pyr–C 4)=(2.1±0.4)×10 −2 m mN −1, κ(C 60pyr–C 8)=(3.5±0.4)×10 −2 m mN −1 and κ(C 60pyr–C 12)=(4.1±0.5)×10 −2 m mN −1, as expected for the liquid surface films. The values of surface area at zero surface pressure ( A 1) differ in the range 0.6 nm 2 molecule −1 (for m=4–8) to 1.4 nm 2 molecule −1 (for m=10–12), indicating that all 2-( n-alkyl)fulleropyrrolidines form multilayer or aggregated films on neutral water subphase. However, acidification of the water subphase increases the A 1 values for all investigated fulleropyrrolidines up to ca. 1.9 nm 2 molecule −1, i.e., the value corresponding to maximum area occupied by a fulleropyrrolidine at horizontal orientation in a monolayer film. Apparently, 2-( n-alkyl)fulleropyrrolidinium cations formed at low pH are markedly de-aggregated in the films and their orientation is changed due to protonation of the pyrrolidine nitrogen. Similarly, however, less pronounced effects are observed if ionic strength of the subphase solution, I, is increased in the range 0≤ I≤1.0 mol dm −3 NaCl. The Langmuir films formed on a water subphase were the most stable with respect to the LB transfer onto 5 MHz Au–quartz crystal vibrators. Simultaneous cyclic voltammetry and piezoelectric microgravimetry at an electrochemical quartz crystal microbalance of these films showed at least two electroreductions where the fulleropyrrolidine mono anions were stable with respect to dissolution.

Reactions of [RuCl2(NO)(terpy)]+ (terpy = 2,2′ : 6′,2″-terpyridine) with mono anions such as NO2–, Br– and N3–, and structural studies on terpyridineruthenium having a nitrosyl ligand

[RuCl2(NO)(terpy)]PF6 ([1]PF6) has been synthesized by the reaction of K2[RuCl5(NO)] with terpy and characterized by single-crystal X-ray crystallography. [1]PF6 has a structure in which the two chloro ligands are located trans to each other with the nitrosyl ligand on the plane of the terpy ligand. Reactions of [1]PF6 with mono anions such as NO2−, Br− and N3− have been investigated. Its reactions with NO2− in H2O and CH3OH afford nitrosylterpyridineruthenium complexes, [Ru(OH)(NO2)(NO)(terpy)]PF6 ([2]PF6) and [RuCl(OCH3)(NO)(terpy)]PF6 ([3]PF6), respectively, whose geometrical configurations differ from that of [1]+. The Br−-substituted complex of [1]+, [RuBr2-(NO)(terpy)]PF6 ([4]PF6), and two solvated complexes, [RuCl2(CH3CN)(terpy)] ([5]) and [RuCl(CH3CN)2(terpy)]PF6 ([6]PF6), have been formed in its reactions with Br− and N3−. Structures of [2]PF6, [3]PF6 and [4]PF6 have been determined by singal-crystal X-ray crystallography and compared with each other.

Mixtures of Trihalide Anions in Isostructural BEDT-TTF Salts as Seen by Raman Spectroscopy

Low frequency Raman spectra have been recorded at room temperature for β-type structure of the (BEDT-TTF)2X single crystals (where BEDT-TTF is bis(ethylenedithio) tetrathiafulvalene and X stands for mono or mixed trihalide anions). This technique has permitted us to detect a presence of the (Br-I-Cl)−, (I-I-Cl)− and (Cl-I-Cl)− anions in addition to a mixture of the (I-I-I)−, (I-I-Br)− and (Br-I-Br)− anions in some recently grown single crystals. The observed low-frequency Raman bands were compared with the ab initio calculated vibrational frequencies of trihalide anions and a very good agreement between experimental and calculated data was found.

The universality of the electron spin relaxation in C60 mono radical anion salts: EPR studies of the model system [P(C6H5)4]2C60X

The C60 radical anion salts [P(C6H5)4]2C60X (X=Cl, Br, I) are grown via electrocrystallization and used as a model system to study the electron spin and nuclear spin dynamics as well as the molecular dynamics of C60 mono anions in the solid state, which obey universal laws. It is shown that [P(C6H5)4]2C60X is an exception among the fullerides, since the temperature dependence of the JT distortion, predicted for ionic C60, can be deduced.

Acid sensitivity as affected by physico-chemical stresses in Aeromonas hydrophila.

This work focuses mainly on the effect of NaCl along with other mono and divalent anions and cations at pH 4 on survival and virulence properties of Aeromonas hydrophila. To find the optimum stress condition, effects of several other physical factors on NaCl induction were also assayed. A. hydrophila collected from International Center for Diarrheal Disease Research, Bangladesh (ICDDR,B) was found to be more sensitive to pH 4.0 when grown in media containing 200 mM or more salt. Induction of acid sensitivity was rapidly gained in NaCl-supplemented broth at 37 C. There was only slight sensitization after 5 min, but a marked effect was observed within 30 min. Uninduced A. hydrophila gave an average of 40% survival after exposure to pH 4.0 for 5 min. However, NaCl-induced cells of this organism reduced the survival to a great extent having an average of 0.06%. Either increase in salt concentration (100 mM through 400 mM) or decrease (50 mM) resulted in decrease in percent survival when exposed to gradually increased concentrations of salt. The most effective dose for induction was 400 mM NaCl salt. NaCl-induction was found to be more pronounced in log-phase organisms. All other monovalent and divalent anions and cations tested were almost as effective as NaCl except KCl.

Transition from static to dynamic Jahn-Teller distortion in (P(C 6H 5) 4) 2C 60I

Air stable bulk single crystals of (P(C 6H 5) 4) 2C 60I can be grown by electrocrystallisation. We will prove that this salt is an excellent model system for the ferromagnetic [TDAE]C 60 and furthermore a good tool, to study the dynamics of C 60 mono anions in the solid state. We could directly observe the temperature dependence of the Jahn-Teller distortion of the C 60- and the transition from a static to a dynamic Jahn-Teller distortion at about 140 K. We will present detailed EPR linewidth and g-factor measurements at 9.7 and 34 GHz between 3.5 and 300 K.

PHOSPHOROCHLORIDATE AND DICHLOROTHIOATE IONS: APROTIC ACCESS AND EVIDENCE FOR CHLORIDE ION RELEASE TO FORM METAPHOSPHATE TYPE INTERMEDIATES

Abstract Monomeric, non-coordinated salts of the dichlorophosphoric, dichlorophosphorothioic and dithioic acid are obtained in high yields by dealkylation of the corresponding methyl esters using quaternary ammonium or phosphonium halides. The mono and dithioate anions react under mild conditions with 4-dimethylaminopyridine as trapping agent to form the thiometaphosphate adducts 11b and 11c. respectively. whereas the dichlorophosphate anion merely yields condensation products. The capability of the title compounds to act as metaphosphate type precursors by chloride ion release may be compared with the analogous behaviour of phosphorochloroimidate and chlorosulfate anions.

Synthesis of bis(alkylthio)bipyridils by nickel mediated homo coupling of halogenopyridyl alkyl sulphides

The homo coupling of some halogenopyridyl t-butyl sulphides with Ni(O) complex, formed in situ from nickel(II) chloride, triphenylphosphine and zinc dust in DMF, afforded bis(t-butylthio)bipyridyls in moderate to good yield. These compounds were dealkylated by electron transfer with sodium in HMPA; the resulting thiolate anions were directly treated with methyl iodide and the bis(methylthio)bipyridyls were obtained. The dealkylation with a solution of sodium in HMPA afforded the mono anions which, after treatment with methyl iodide, gave the t-butylthio(methylthio)bipridyls.

ChemInform Abstract: CHARACTERIZATION OF CHLOROCLOSOBORANE ACIDS AS ELECTROLYTES FOR ACID FUEL CELLS

AbstractH2B"C1" und HzßmCllo werden durch Ionenaustausch oder Elektrolyse durch eine Nation 125‐Membran aus den entsprechenden handelsüblichen Li‐Salzen in hochreiner Form dargestellt (Entwicklung von Reinigungprozeduren) und durch IR‐, Elektronen‐, N MR‐ und Massenspektren charakterisiert.

Characterization of Chloroclosoborane Acids as Electrolytes for Acid Fuel Cells

The perchloroclosoborane acids, and , were prepared in high purity and investigated as alternative electrolytes to in moderate temperature acid fuel cells. Procedures were developed for the purification of the acids prepared from commercially available salts. The purified acids were characterized by infrared, electronic, NMR, and mass spectroscopy. Concentrated aqueous solutions of the acids were found to have low ionic conductivity and a moderate water vapor pressure. The mono anions, and , formed from reactions of concentrated aqueous solutions or the solid hydrates of the acids. The and anions were also found to adsorb on electrocatalytic Pt surfaces.

PREPARATION AND ELECTROCHEMICAL BEHAVIORS OF IRON(III) OCTAETHYLPORPHYRINS COORDINATED BY CATECHOL MONO ANIONS

Abstract Iron(III) octaethylporphyrin complexes coordinated by mono anions of catechol and 3,5-di-tert-butylcatechol were prepared. These Fe(III) high-spin complexes showed an irreversible one-electron redox couple for the coordinated catechol anion, in addition to two one-electron quasi-reversible FeII/FeIII, and FeIII/FeIV redox couples.