The water-soluble indolium-based fluorescence probes for detection of the extreme acidity or extreme alkalinity

In this work, 3,3′-(((1E,1′E)-(H,12H-5,11-methanodibenzo[b,f][1,5]diazocine-2,8-diyl)bis(ethene-2,1-diyl))bis(1,1-dimethyl-1H-benzo[e]indole-3-ium-2,3-diyl))bis(propane-1-sulfonate) (1), 3,3’-(((1E,1′E)-(6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine-2,8-diyl)bis(ethene-2,1-diyl))bis(3,3-dimethyl-3H-indole-1-ium-2,1-diyl))bis(propane-1-sulfonate) (2), 2,2’-((1E,1′E)-(6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine-2,8-diyl)bis(ethene-2,1-diyl))bis(1,3,3-trimethyl-3H-indol-1-ium) iodide (3) and 2,2’-((1E,1′E)-(6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine-2,8-diyl)bis(ethene-2,1-diyl))bis(1,1,3-trimethyl-1H-benzo[e]indol-3-ium) iodide (4) were designed and synthesized by ethylene bridging of the N-substituted indolium salts and the Tröger’s Base (TB) framework. The probes exhibited a longer absorption and emission wavelength and the emission wavelength of them in dichloromethane (DCM) was more than 600 nm, performed a red fluorescence. All of the probes could work on the extreme acidic and the extreme alkaline environments and showed a good liner response in the working pH range. Especially, 2 and 4 were soluble in water and manifested a good pH sensing in a water system. Also, ¹H NMR analysis illustrated how these dyes worked as the pH-sensitive fluorescence probes. In addition, they performed excellent reversibility, high selectivity and good photostability.     

Supernucleophilic systems based on functionalized surfactants in the decomposition of 4-nitrophenyl esters derived from phosphorus and sulfur acids: II. Influence of the length of hydrophobic alkyl substituents on micellar effects of functionalized monomeric and dimeric imidazolium surfactants

New dimeric functionalized surfactants, 3,3′-[2-(hydroxyimino)propan-1,3-diyl]bis(1-alkyl-1H-imidazol-3-ium) dichlorides (Alk = C₁₂H₂₅, C₁₄H₂₉, C₁₆H₃₃), underlie the supernucleophilic microorganized systems capable of abnormally fast cleavage of acyl-containing substrates. Micellar effects both of monomeric and dimeric imidazolium surfactants in the cleavage processes of 4-nitrophenyl esters of diethylphosphonic, diethylphosphoric, and 4-toluenesulfonic acids are governed mostly by the hydrophobicity of the reaction components (acceleration ～10²–10³ times). The unquestionable advantage of dimeric surfactants is their especially low critical micelle concentrations (≤10^?5 mol L^?1), providing a possibility to attain the same micellar effects at the surfactant concentration lower by an order of magnitude (and yet even lower) than in the case of monomeric analogs.     

Bisthiourea: thermal and structural investigation

Bisthiourea derivatives 1,1′-(ethane-1,2-diyl)bis(3-phenylthiourea), 1,1′-(propane-1,3-diyl)bis(3-phenylthiourea), and 1,1′-(butane-1,4-diyl)bis(3-phenylthiourea) have been synthesized and characterized by IR, ¹H NMR, and ¹³C NMR. Suitable crystals of 1,1′-(propane-1,3-diyl)bis(3-phenylthiourea) were grown for single-crystal X-ray analysis and from the data it was observed that they organize into the P-1 space group. The thermal decomposition of these compounds has been studied by TG–DSC.     

“Seems Bad Turns Good” – traces of precursor in dicationic ionic liquid lead to analytical application

Research on Chemical Intermediates - We explored a geminal dicationic ionic liquid (DCIL), 1′-(propane-1,3-diyl)bis(4-aminopyridin-1-ium) dibromide, [C3(Amp)2][Br]2, as a fluorescent probe...     

Synthesis,binding and fluorescence studies of a new neutral H-bonding receptor for anions based on 3,5-bis(trifluoromethyl)phenylurea

The synthesis and anion binding studies of the new neutral receptor 1,1′-(2,2′-(4,10-dimethyl-1,4,7,10-tetraazacyclododecane-1,7-diyl)bis(2-oxoethane-2,1-diyl))bis(3-(3,5-bis(trifluoromethyl)phenyl)urea) (L1) are reported. L1 is a macrocyclic ligand containing the 3,5-trifluoromethylphenylureido-binding fragment attached as a side arm on the tetraazacyclododecane. L1 is soluble in numerous organic solvents; the binding properties of L1 towards several simple anions (G) were investigated by NMR, UV–vis and fluorescence techniques in DMSO and CH₃CN solutions. L1 is able to bind F^? , Cl^?  and AcO^?  in both solvents; in addition, it binds Br^?  in CH₃CN. Fluoride shows the highest constant values in the halide series (F^?  > Cl^?  > Br^? ) and AcO^?  is the most strongly bound among all the anions investigated. L1 is able to signal the presence of the anions in solution by fluorescence change; in the case of acetate, this occurs in the visible range.     

Use of ionic liquid based chitosan as sorbent for preconcentration of fluoroquinolones in milk,egg, fish,bovine, and chicken meat samples by solid phase extraction prior to HPLC determination

The possibility of using ionic liquid based chitosan sorbent for the separation and preconcentration of fluoroquinolone antibiotics (marbofloxacin, enoxacin, ofloxacin, ciprofloxacin, and enrofloxacin) has been studied. For this reason, different ionic liquids were prepared and coated on the chitosan sorbent. The conditions of the preconcentration of fluoroquinolones on a microcolumn have been optimized and the extraction efficiencies of the prepared sorbents have been compared. The compounds were eluted with 5 mL of 20% NH₃ (v/v, MeOH) solution and determined by HPLC with diode array and fluorescence detector. The limits of detection were found as 4.23 µ g L^?1 for marbofloxacin, and 1.09 µg L^?1 for enoxacin; 3.23 × 10^?3 µg L^?1 for ofloxacin; 8.39 × 10^?3 µg L^?1 for ciprofloxacin; and 19.50 × 10^?3 µg L^?1 for enrofloxacin. The developed method was applied for the analysis of fluoroquinolone in milk, egg, fish, bovine, and chicken samples and the recoveries were obtained in the range 70–100%.     

Catalytic [6<Emphasis Type="Italic">π</Emphasis> + 2<Emphasis Type="Italic">π</Emphasis>]-Cycloaddition of 1,2-Dienes to Bis(cyclohepta-1,3,5-trien-7-yl)alkanes in the Presence of Ti(acac)<Subscript>2</Subscript>Cl<Subscript>2</Subscript>,–Et<Subscript>2</Subscript>AlCl

An efficient procedure has been developed for the synthesis of difficultly accessible 9,9′-(alkane-α,ω-diyl)bis[7-(diphenylmethylidene)bicyclo[4.2.1]nona-2,4-dienes] and 16,16′-(alkane-α,ω-diyl)bis(tricyclo-[9.4.1.0^2,10]hexa-2,12,14-trienes) in 55–84% yields by [6π + 2π]-cycloaddition of 7,7′-(alkane-α,ω-diyl)bis-(cyclohepta-1,3,5-trienes) to 1,1-diphenylpropa-1,2-diene and cyclonona-1,2-diene in the presence of the catalytic system Ti(acac)₂Cl₂–Et₂AlCl. The structure of the isolated compounds has been reliably proved by modern spectral methods.     

Organic Diodes Based on Redox-Polymer Bilayer-Film-Modified Electrodes

The synthesis of four electropolymerizable 2,2′-bipyridinium salts with tuned reduction potential (E₁^°) is described (N,N′-ethylene-4-methyl-4′-vinyl-2,2′-bipyridinium dibromide ( 4 ; E₁^° ?–0.48 V), 4-methyl-N, N′-(trimethylene)-4′-vinyl-2,2′-bipyridinium dibromide ( 5 ; E₁^°? ?0.66 V), N,N′-ethylene-4-methyl-4′-[2-(1H-pyrrol-1-yl)ethyl]-2, 2′-bipyridinium bis(hexafluorophosphate) ( 6b ; E₁^°? ?0.46 V), and 4-methyl-4′-[2-(1H-pyrrol-1-yl)ethyl]-N, N′-(trimethylene)-2,2′-bipyridinium bis(hexafluorophosphate) ( 7b ; E₁^°? ?0.66 V)). E₁^°-Tuning is based on the torsional angle C(3)–C(2)–C(2′)–C(3′), imposed by the N,N′-ethylene and N,N′-(trimethylene) bridge. The vinylic compounds 4 and 5 undergo cathodic, the pyrrole derivatives 6b and 7b anodic electropolymerization on glassy carbon electrodes from MeCN solutions, yielding thin, surface-confined films with surface concentrations of redox-active material in the range 5 · 10^?9 < Γ < 2.10^?8 mol/cm², depending on experimental conditions. The modified electrodes exhibit reversible ‘diquat’ electrochemistry in pure solvent/electrolyte. Copolymerization of 6b or 7b with pyrrole yields most stable electrodes. Bi ayer-film-modified electrodes were prepared by sequential electropolymerization of the monomers. The assembly electrode/poly- 6b /poly- 7b behaves as a switch, it transforms – as a Schmitt trigger – an analog input signal (the electrode potential) into a digital output signal (redox state of the outer polymer film). Forward-(electrode/poly- 7b /poly- 6b ) and reverse-biased assemblies (electrode/poly- 6b /poly- 7b ) were coupled to the electrochemical reduction of redox-active solution species, e.g. N- (cyanomethyl)-N′-methyl-4,4′-bipyridinium bis(hexafluorophosphate) ( 8 ). Zener-diode-like behavior was observed. Aspects of redox-polymer multilayer-film assemblies, sandwiched between two electronic conductors, are discussed in terms of molecular electronic devices.     

A dicationic ionic liquid-modified phosphotungstate hybrid catalyst for the heterogeneous oxidation of alcohols with H2O2

An ionic hybrid catalyst 1,1’-(butane-1,4-diyl)-bis(3-methylimidazolium) phosphotungstate(abbreviated [Dmim] 1.5 PW) has been prepared by anion-exchange of the divalent ionic liquid(IL) 1,1’-(butane-1,4-diyl)-bis(3-methylimidazolium) di(bromide) with the Keggin phosphotungstic acid H 3 PW 12 O 40,and characterized by IR,1 H NMR,13 C NMR,ESI-MS,TG,SEM,XRD,BET surface area measurements,elemental analysis,and melting point.The hybrid material was evaluated as a catalyst for the oxidation of alcohols with aqueous hydrogen peroxide under various conditions.The catalytic performance of [Dmim] 1.5 PW was also compared with related catalysts bearing other cations or anions.The new hybrid [Dmim] 1.5 PW proved to be an efficient liquid-solid heterogeneous catalyst for H2O2-based oxidation of alcohols,with the advantages of high conversion and selectivity,easy recovery,and quite good reusability.     

Ionic liquids versus ionic liquid-based surfactants in dispersive liquid–liquid microextraction for determining copper in water by flame atomic absorption spectrometry

This work compares the performance of dispersive liquid–liquid method (DLLME) as a prior step for determining copper by flame atomic absorption spectrometry (FAAS), when using the ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate (C₄MIm-PF₆) or the IL-based surfactant 1-hexadecyl-3-butylimidazolium bromide (C₁₆C₄Im-Br) as extractant solvents. For the water-insoluble C₄MIm-PF₆, the most conventional DLLME mode using acetonitrile as dispersive solvent was employed. For the water-soluble C₁₆C₄Im-Br, the in situ DLLME mode with lithium bis[(trifluoromethane)sulfonyl]imide (Li-NTf₂) as metathesis reagent was employed. In both approaches, some effective parameters such as volumes of extractant and dispersive solvents, concentration of complexing agent, pH of sample solution, salting-out effect and final diluting solvent to ensure compatibility with FAAS, were properly optimised. The optimum conditions for the IL-DLLME method using C₄MIm-PF₆ were: 100 μL of neat C₄MIm-PF₆, 1 mL of acetonitrile, 10 mL of water, no control of pH for environmental waters, NaCl content of 23 g L^?1, diethyl dithiocarbamate (DDTC) as complexing agent at 10 mg L^?1 and final dilution of the micro-droplet with acetonitrile up to 70 µL. The optimum conditions for the in situ IL-DLLME method using C₁₆C₄Im-Br were: 0.8 mL of acetonitrile, 10 mL of water containing C₁₆C₄Im-Br at 25.2 mmol L^?1, final dilution step of the micro-droplet with 200 µL of acetonitrile and remaining conditions as those of C₄MIm-PF₆. The analytical performance of both methods was similar, being slightly better for the IL-DLLME method using C₄MIm-PF₆, with limits of detection (LOD) of 3.3 µg L^?1 (versus 5.1 µg L^?1 when using C₁₆C₄Im-Br), precision values as intraday relative standard deviation (RSD in %) lower than 8.8% (being of 10% for the C₁₆C₄Im-Br method) and an enrichment factor of 54 (being 27 when using C₁₆C₄Im-Br). The DLLME-FAAS method with C₄MIm-PF₆ was used in the analysis of environmental waters with successful performance, with relative recoveries of 110% and 105%, and interday precision with RSD values of 21% and 7.4% for spiked levels of 60 and 160 µg L^?1, respectively. The results obtained when analysing an urban wastewater sample coming from an inter-laboratory exercise was comparable to those obtained for other 93 laboratories. The method was also valid for the determination of Cu²⁺ in presence of foreign ions commonly found in natural waters.     

Construction of a PbII coordination polymer from a semi-rigid ditopic 2,2-biimidazole derivative: synthesis,crystal structure and characterization

<!?tlsb=-0.04pt>A new Pb^II coordination polymer, poly[0.75(aqua)[μ₃-4,4′-(1H,1′H-[2,2′-biimidazole]-1,1′-diyl)dibenzoato-κ⁵O,O′;N;O′′,O′′′]]lead(II)] 1.25-hydrate], {[Pb(C₂₀H₁₂N₄O₄)(H₂O)_0.75]·1.25H₂O}_n or {[Pb(L)(H₂O)_0.75]·1.25H₂O}_n ( 1 ) [H₂L = 4,4′-(1H,1′H-[2,2′-biimidazole]-1,1′-diyl)dibenzoic acid], was synthesized under solvothermal reaction conditions and characterized using microanalysis, IR spectroscopy and thermogravimetric analysis. Single-crystal structure analysis reveals that a two-dimensional corrugated layer structure is formed in 1 and that neighbouring layers are further extended into a three-dimensional structure by hydrogen-bonding interactions. In addition, a fluorescence sensing experiment towards Cu²⁺ based on the polymeric Pb^II complex was carried out.     

Tetramethyldisilan-1,2-diyl-verbrückte Dicyclopentadienyl-und Diindenylmetalldichloride der 4. Gruppe – Kristallstruktur von

Tetramethyldisilane-1,2-diyl bridged Dicyclopentadienyl and Diindenyl Metal Dichlorides of the Group 4 Metals – Crystal Structure of Dicyclopentadienyl and diindenyl metal dichlorides of the type Cp′? SiMe₂SiMe₂? Cp′MCl₂ (Cp′ = C₅H₄, M = Ti ( 1 ), Zr ( 2 ), Hf ( 3 ); Cp′ = C₉H₇, M = Zr ( 4 ), Hf ( 5 )) were synthesized and characterized by means of their ¹H, ¹³C, ²⁹Si-n.m.r., MS, and IR spectra. The crystal structure of 2 was determined.     

Synthesis of (1H-pyrrol-2-ylsulfanyl)alkanoic acids

(1-Benzyl-1H-pyrrol-2-ylsulfanyl)acetic acid, 2- and 3-(1-benzyl-1H-pyrrol-2-ylsulfanyl)propionic acids, 1,1′-[1,4-phenylenebis(methylene)]bis[(1H-pyrrol-2-ylsulfanyl)acetic acid], and 1,1′-(hexane-1,6-diyl)bis-[(1H-pyrrol-2-ylsulfanyl)acetic acid] were synthesized for the first time by reactions of 1-benzyl-1H-pyrrole, 1,1′-[1,4-phenylenebis(methylene)]bis(1H-pyrrole), and 1,1′-(hexane-1,6-diyl)bis(1H-pyrrole) with thiourea, iodine, and the corresponding halogen-substituted alkanoic acids. 1-(4-Nitrophenyl)-1H-pyrrole failed to react with thiourea and iodine.     

Chiral and Nonchiral [OsX2(diphosphane)(diamine)] (X: Cl,OCH2CF3) Complexes for Fast Hydrogenation of Carbonyl Compounds

The osmium complexes trans‐[OsCl₂(dppf)(diamine)] (dppf: 1,1′‐bis(diphenylphosphino)ferrocene; diamine: ethylenediamine in 3 , propylenediamine in 4 ) were prepared by the reaction of [OsCl₂(PPh₃)₃] ( 1 ) with the ferrocenyl diphosphane, dppf and the corresponding diamine in dichloromethane. The reaction of derivative 3 with NaOCH₂CF₃ in toluene afforded the alkoxide cis‐[Os(OCH₂CF₃)₂(dppf)(ethylenediamine)] ( 5 ). The novel precursor [Os₂Cl₄(P(m‐tolyl)₃)₅] ( 2 ) allows the synthesis of the chiral complexes trans‐[OsCl₂(diphosphane)(1,2‐diamine)] ( 6 – 9 ; diphosphane: (R)‐[6,6′‐dimethoxy(1,1′‐biphenyl)‐2,2′‐diyl]bis[1,1‐bis(3,5‐dimethylphenyl)phosphane] (xylMeObiphep) or (R)‐(1,1′‐binaphthalene)‐2,2′‐diylbis[1,1‐bis(3,5‐dimethylphenyl)phosphane] (xylbinap); diamine=(R,R)‐1,2‐diphenylethylenediamine (dpen) or (R,R)‐1,2‐diaminocyclohexane (dach)), obtained by the treatment of 2 with the diphosphane and the 1,2‐diamine in toluene at reflux temperature. Compounds 3 – 5 in ethanol and in the presence of NaOEt catalyze the reduction of methyl aryl, dialkyl, and diaryl ketones and aldehydes with H₂ at low pressure (5 atm), with substrate/catalyst (S/C) ratios of 10 000–200 000 and achieving turnover frequencies (TOFs) of up to 3.0×10⁵ h^?1 at 70 °C. By employment of the chiral compounds 6 – 9 , different ketones, including alkyl aryl, bulky tert‐butyl, and cyclic ketones, have successfully been hydrogenated with enantioselectivities up to 99 % and with S/C ratios of 5000–100 000 and TOFs of up to 4.1×10⁴ h^?1 at 60 °C.     

A rapid selective colorimetric and ‘On–Off’ fluorimetric sensor for detecting Cu2+ ions in aqueous media based on a simple bis-schiff-base derivative

A simple colorimetric and fluorimetric ‘On–Off’ sensor L (3,3′-dimethyl -[1,1′-biphenyl]-4,4′-diyl)bis(azanylylidene)bis(methanylylidene)bis(naphthalen-2-ol) for Cu²⁺ ions bearing o-tolidine substituents has been designed and synthesised, and exhibits significant fluorimetric and colorimetric response for Cu²⁺ in DMSO/H₂O (8:2, v/v) HEPES buffer (pH 7.2) solution. The detection limit of the sensor towards Cu²⁺ is 7.25 × 10^? 8 M and the association constant K_a of 9.86 × 10⁴ M^? 1 was determined. Furthermore, other anions, including Fe³⁺, Hg²⁺, Ag⁺, Ca²⁺, Co²⁺, Ni²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Cr³⁺ and Mg²⁺ have almost no influence on the probe's behaviour. Test strips based on the sensor L were fabricated, which could act as convenient and efficient Cu²⁺ test kits.     

DFT Study of the Geometrical and Electronic Structures of Geminal Dicationic Ionic Liquids 1,3‐Bis[3‐methylimidazolium‐1‐yl]hexane Halides

In this work, the geometrical and electronic properties of the mono cationic ionic liquid 1‐hexyl‐3‐methylimidazolium halides ([C₆(mim)]⁺_X^?, X=Cl, Br and I) and dicationic ionic liquid 1,3‐bis[3‐methylimidazolium‐1‐yl]hexane halides ([C₆(mim)₂X₂], X=Cl, Br and I) were studied using the density functional theory (DFT). The most stable conformer of these two types ionic liquids (IL) are determined and compared with each other. Results show that in the most stable conformers, in both monocationic ILs and dicationic ILs, the Cl^? and Br^? anions prefer to locate almost in the plane of the imidazolium ring whereas the I^? anion prefers nearly vertical location respect to the imidazolium ring plan. Comparison of hydrogen bonding and ionic interactions in these two types of ionic liquids reveals that these ionic liquids can be formed hydrogen bond by Cl^? and Br^? anion. The calculated thermodynamic functions show that the interaction of cation — anion pair in the dicationic ionic liquids are more than monocationic ionic liquids and these interactions decrease with increasing the halide anion atomic weight.     

A one‐dimensional zinc(II) coordination polymer incorporating [1,1′‐biphenyl]‐4,4′‐dicarboxylate and N,N′‐bis(pyridin‐3‐ylmethyl)‐[1,1′‐biphenyl]‐4,4′‐dicarboxamide ligands

In the title compound, catena‐poly[[[N,N′‐bis(pyridin‐3‐ylmethyl)‐[1,1′‐biphenyl]‐4,4′‐dicarboxamide]chloridozinc(II)]‐μ‐[1,1′‐biphenyl]‐4,4′‐dicarboxylato‐[[N,N′‐bis(pyridin‐3‐ylmethyl)‐[1,1′‐biphenyl]‐4,4′‐dicarboxamide]chloridozinc(II)]‐μ‐[N,N′‐bis(pyridin‐3‐ylmethyl)‐[1,1′‐biphenyl]‐4,4′‐dicarboxamide]], [Zn₂(C₁₄H₈O₄)Cl₂(C₂₆H₂₂N₄O₂)₃]_n, the Zn^II centre is four‐coordinate and approximately tetrahedral, bonding to one carboxylate O atom from a bidentate bridging dianionic [1,1′‐biphenyl]‐4,4′‐dicarboxylate ligand, to two pyridine N atoms from two N,N′‐bis(pyridin‐3‐ylmethyl)‐[1,1′‐biphenyl]‐4,4′‐dicarboxamide ligands and to one chloride ligand. The pyridyl ligands exhibit bidentate bridging and monodentate terminal coordination modes. The bidentate bridging pyridyl ligand and the bridging [1,1′‐biphenyl]‐4,4′‐dicarboxylate ligand both lie on special positions, with inversion centres at the mid‐points of their central C—C bonds. These bridging groups link the Zn^II centres into a one‐dimensional tape structure that propagates along the crystallographic b direction. The tapes are interlinked into a two‐dimensional layer in the ab plane through N—H...O hydrogen bonds between the monodentate ligands. In addition, the thermal stability and solid‐state photoluminescence properties of the title compound are reported.     

Silver(I), nickel(II) N-heterocyclic carbene complexes based on bidentate bis-imidazolium salt with a quinoxaline linker: syntheses,structures, and characterization

Quinoxaline-bridged bidentate bis-imidazolium dicarbene ligand 1,1′-(quinoxaline-2,3-diyl)bis(3-methyl-1H-imidazol-3-ium) hexafluorophosphate salt H₂L·2PF₆ (3) was prepared by a two-step reaction based on 2,3-bis(imidazol-1-yl)quinoxaline (1). First, the 2,3-bis(imidazol-1-yl)quinoxaline reacted with CH₃I resulting in the 1,1′-(quinoxaline-2,3-diyl)bis(3-methyl-1H-imidazol-3-ium) iodide salt H₂L·2I (2), then through anion exchange reactions with NH₄PF₆ in water produced the desired bis-imidazolium bidentate ligand H₂L·2PF₆ (3). Reaction of the bidentate bis-imidazolium ligands H₂L·2PF₆ (3) with Ag₂O in acetonitrile gave the macrocyclic binuclear silver(I) carbene complex [Ag₂(L)₂]·2PF₆·CH₃CN (4). Nickel carbene complex [Ni(L)PPh₃Cl]·PF₆·2DMSO (5) was obtained via transmetalation of 4 with Ni(PPh₃)₂Cl₂ in DMSO. The bidentate carbene ligand is a chelating ligand in 5, while bridging in 4. The imidazolium ligand H₂L·2PF₆ (3) and transition metal carbene complexes 4 and 5 have been fully characterized by elemental analysis, NMR, ESI-MS spectroscopy, and X-ray diffraction analyses. Furthermore, the UV and luminescent properties of 3–5 were also studied.     

Conductivity,structure, and thermal properties of chitosan‐based polymer electrolytes with nanofillers

This paper focus on the effect of nanosize (<50 nm BET) inorganic alumina (Al₂O₃) filler on the structural, conductivity, and thermal properties of chitosan‐based polymer electrolytes. Films of chitosan and its complexes were prepared using solution‐casting technique. Different amounts of Al₂O₃ viz., 3, 4.5, 6, 7.5, 9, 12, and 15 wt% were added to the highest room temperature conducting sample in the chitosan–salt system, i.e. sample containing 60 wt% chitosan–40 wt% NH₄SCN. The conductivity value of the sample is 1.29 × 10^?4 S cm^?1. On addition of 6 wt% Al₂O₃ filler the ionic conductivity increased to 5.86 × 10^?4 S cm^?1. The amide and amino peaks in the spectrum of chitosan at 1636 and 1551 cm^?1, respectively, shift to lower wavenumbers on addition of salt. The glass transition temperature T_g for the highest conducting composite is 190°C. The increase in T_g with increase in more than 6 wt% filler content is attributed to the increase in degree of crystallinity as proven from X‐ray diffraction studies. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthese von triafulvalen-vorstufen durch ‘carben-dimerisierung’ von 1-halogeno-1-lithiocyclopropanen

Synthesis of Triafulvalene Precursors by ‘Carbene-Dimerization’ of 1-Halogeno-1-lithiocyclopropanes Bi(cyclopropylidenes) 7a , 7c , and 7e are available in a simple one-pot reaction by treating 1,1-dibromocyclo-propanes 5 at ?95° with BuLi and CuCl₂. Attempts towards triafulvalene precursors with good leaving groups are reported. The most promising attempt makes use of 2,2′-bis(phenylthio)-3,3′-bis(trimethylsilyl)-1,1′-bi(cyclopropylidene) (7c) which has been oxidized to give the bis(phenylsulfonyl) derivative 7g. So far, F^?-induced elimination experiments with 7g failed.