Conductive plastic crystal phases of the 1-alkyl-2-methyl pyrrolinium TFSA salts

Characterization of a new family of salts, based on a number of 1-alkyl-2-methyl pyrrolinium cations and the bis(trifluoromethane sulfonyl) amide anion (TFSA), is presented. From the thermal analysis, conductivity and X-ray diffraction (XRD) measurements, at least one of the compounds of the family, 1-ethyl-2-methyl pyrrolinium TFSA, was found to exhibit plastic crystal phases before melting and to exhibit high conductivity in the solid state (1×10⁻⁴ S cm⁻¹ at 25 °C). This plastic crystal behaviour is discussed in comparison with other members of this pyrrolinium salt family.

A new family of ionic liquids based on the 1-alkyl-2-methyl pyrrolinium cation

Five new salts based on 1-alkyl-2-methyl pyrrolinium ion are reported, two involving the iodide ion and three involving the bis(trifluoromethanesulfonyl) amide ion. The iodide salts have melting points around 100 °C, while the amide salts have melting points around room temperature. Two of the amide salts can be easily quenched into the glassy state and exhibit glass transition temperatures around −70 °C. The 2-methyl pyrrolinium cation bears structural similarities to the aromatic imidazolium cations on one hand and the cyclic ammonium cation family based on the pyrrolidinium cation on the other. The properties of the salts reported here are compared within these two related families of salts.

π-Selective stationary phases: (II) Adsorption behaviour of substituted aromatic compounds on n-alkyl-phenyl stationary phases

The frontal analysis method was used to measure the adsorption isotherms of phenol, 4-chlorophenol, p-cresol, 4-methoxyphenol and caffeine on a series of columns packed with home-made alkyl-phenyl bonded silica particles. These ligands consist of a phenyl ring tethered to the silica support via a carbon chain of length ranging from 0 to 4 atoms. The adsorption isotherm models that fit best to the data account for solute–solute interactions that are likely caused by π–π interactions occurring between aromatic compounds and the phenyl group of the ligand. These interactions are the dominant factor responsible for the separation of low molecular weight aromatic compounds on these phenyl-type stationary phases. The saturation capacities depend on whether the spacer of the ligands have an even or an odd number of carbon atoms, with the even alkyl chain lengths having a greater saturation capacity than the odd alkyl chain lengths. The trends in the adsorption equilibrium constant are also significantly different for the even and the odd chain length ligands.

Robust, electro-conductive, self-healing superamphiphobic fabric prepared by one-step vapour-phase polymerisation of poly(3,4-ethylenedioxythiophene) in the presence of fluorinated decyl polyhedral oligomeric silsesquioxane and fluorinated alkyl silane

A robust, electrically conductive, superamphiphobic fabric was prepared by vapour-phase polymerisation of 3,4-ethylenedioxythiophene (EDOT) on fabric in the presence of fluorinated decyl polyhedral oligomeric silsesquioxane (FD-POSS) and a fluorinated alkyl silane (FAS). The coated fabric had contact angles of 169° and 156° respectively to water and hexadecane, and a surface resistance in the range of 0.8–1.2 kΩ o⁻¹ . The incorporation of FD-POSS and FAS into the PEDOT layer showed a very small influence on the conductivity but improved the washing and abrasion stability considerably. The coated fabric can withstand at least 500 cycles of standard laundry and 10000 cycles of abrasion without apparently changing the superamphiphobicity, while the conductivity only had a small reduction after the washing and abrasion. More interestingly, the coating had a self-healing ability to auto-repair from chemical damages to restore the liquid repellency.

Physicochemical characterization of a new family of small alkyl phosphonium imide ionic liquids

Despite their promising properties, phosphonium based ionic liquids have attracted little attention as compared to their nitrogen-based cation counterparts. This study focuses on the properties of a family of small phosphonium imide ionic liquids, as well as the effect of lithium salt addition to these. The 6 ionic liquids were either alkyl, cyclic or nitrile functionalised phoshonium cations with bis(trifluoromethanesulfonyl)imide, NTf2, or bis(fluorosulfonyl)imide (FSI) as anion. Amongst the properties investigated were ionic conductivity, viscosity, thermal behaviour, electrochemical stability and the reversibility of electrochemical lithium cycling. All ionic liquids showed very promising properties e.g. having low transition temperatures, high electrochemical stabilities, low viscosities and high conductivities. Particularly the trimethyl phosphonium ionic liquids showed some of the highest conductivities reported amongst phosphonium ionic liquids generally. The combination of electrochemical stability, high conductivity and reversible lithium cycling makes them promising systems for energy storage devices such as lithium batteries.

2-Amino-3-aroyl-4,5-alkylthiophenes: Agonist allosteric enhancers at human A1 adenosine receptors

2-Amino-3-benzoylthiophenes are allosteric enhancers (AE) of agonist activity at the A₁ adenosine receptor. The present report describes syntheses and assays of the AE activity at the human A₁AR (hA₁AR) of a panel of compounds consisting of nine 2-amino-3-aroylthiophenes (3a-i), eight 2-amino-3-benzoyl-4,5-dimethylthiophenes (12a-h), three 3-aroyl-2-carboxy-4,5- dimethylthiophenes (15a-c), 10 2-amino-3-benzoyl-5,6-dihydro 4H-cyclopenta[b]thiophenes (17a-j), 14 2-amino-3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophenes (18a-n), and 15 2-amino- 3-benzoyl-5,6,7,8-tetrahydro-4H-cyclohepta[b]thiophenes (19a-o). An in vitro assay employing the A₁AR agonist [¹²⁵I]ABA and membranes from CHO-K1 cells stably expressing the hA¹AR measured, as an index of AE activity, the ability of a candidate AE to stabilize the agonist- A₁AR-G protein ternary complex. Compounds 3a-i had little or no AE activity, and compounds 12a-h had only modest activity, evidence that AE activity depended absolutely on the presence of at least a methyl group at C-4 and C-5. Compounds 17a-c lacked AE activity, suggesting the 2-amino group is essential. Polymethylene bridges linked thiophene C-4 and C-5 of compounds 17a-j, 18a-n, and 19a-o. AE activity increased with the size of the -(CH₂)_n- bridge, n ) 3 < n ) 4 < n ) 5. The 3-carbethoxy substituents of 17a, 18a, and 19a did not support AE activity, but a 3-aroyl group did. Bulky (or hydrophobic) substituents at the meta and para positions of the 3-benzoyl group and also 3-naphthoyl groups greatly enhanced activity. Thus, the hA₁AR contains an allosteric binding site able to accommodate 3-aroyl substituents that are bulky and/or hydrophobic but not necessarily planar. A second region in the allosteric binding site interacts constructively with alkyl substituents at thiophene C-4 and/or C-5.

Synthesis, polymerization and wool coating studies of 3-iso-butylpyrrole and 3-iso-pentylpyrrole

In a four-step method starting from pyrrole, the synthesis of 3-iso-butylpyrrole and 3-iso-pentylpyrrole, was achieved in 45 and 44% yields, respectively. Polymerization studies of these branched alkyl pyrroles are described and the results compared with those obtained for the unbranched structural isomers n-butyl and n-pentylpyrrole. A series of conductive textiles were produced by the chemical polymerization of the iso-alkylpyrroles using both solution and vapour polymerization techniques. Fabrics coated with poly-iso-alkylpyrrole formed using the solution polymerization method had a lower surface resistance than those formed using the vapour polymerization method. These conductivity results were in direct contrast to those previously obtained for 3-n-alkylpyrroles on fabrics. A remarkable crystal-like growth on the surface of the textile fabric was observed when solution polymerization of 3-iso-pentylpyrrole was employed—reinforcing the notion that subtle changes in monomer structure can drastically affect bulk polymer properties.

Photochromic wool fabrics from a hybrid silica coating

In this work, a photochromic wool fabric has been prepared by applying a photochromic-dye hybrid silica sol-gel onto the surface of fabric. The photochromic fabric was found to have a very quick optical response. Two types of silica were used as the matrix material, and the type of silica had a small effect only on the photochromic performance, the fabric washing fastness, and water contact angle, but affected the fabric handle property considerably. The silica from a precursor containing a long alkyl chain showed very little influence on the fabric handle and better photochromic performance than that containing a phenyl group.

Room-temperature insertion of elemental tellurium into the Cspł-Br and -I bonds of α-bromo-and α-iodopinacolone

Pinacolyltellurium(IV) dihalides, (t-BuCOCH₂)₂TeX₂ (X ) Br (1b), I (1c)) and Ar(t-BuCOCH₂)TeCl₂ (Ar == 1-C₁₀H₇ (Np) (2a), 2,4,6-Me₃C₆H₂ (Mes) (3a)), are readily prepared at room temperature by the oxidative insertion of elemental tellurium into the C_sp³-Br or -I bond of the α-halopinacolone and by the reaction of ArTeCl₃ with the pinacolone t-BuCOCH₃. The bromides Np(t-BuCOCH₂)TeBr₂ (2b) and Mes(t-BuCOCH₂)TeBr₂ (3b) can be prepared by the addition of bromine to the telluride Ar(t-BuCOCH₂)-Te or of α-bromopinacolone to ArTeBr. Variable-temperature ¹H and ¹³C NMR of the separate signals for the o-Me groups in 3a,b indicate a very high barrier to rotation about the Te-C(aryl) bond. Crystal diffraction data for 1c, 2a-c, and 3b show that intramolecular 1,4-Te …O(C) secondary bonding interactions (SBIs) are retained even in the presence of bulky aryl groups and intermolecular Te …X SBIs are subject to electronic population and steric congestion around the Te(IV) center in the solid state.

Synthesis, characterization and enantioselective free radical reductions of (1R,2S,5R)-menthyldiphenylgermane and its enantiomer

(1R,2S,5R)-Menthyldiphenylgermane and its enantiomer have been prepared in a few steps from germanium tetrachloride. The initial step in this sequence, namely the reaction between germanium tetrachloride and menthylmagnesium chloride, produces menthylgermanium trichloride, which is the exclusive product of this Grignard reaction, presumably due to the bulk of the menthyl group. When used at a low temperature (−78 °C) and in conjunction with Lewis acids, such as magnesium salts, these chiral germanes are capable of reducing ester functionalized radicals in high enantioselectivity, but in low-moderate yield. For example, (R)-naproxen ethyl ester was obtained in 15% yield and 99% ee by reaction in toluene of 2-bromonaproxen ethyl ester with (1R,2S,5R)-menthyldiphenylgermane in toluene at −78 °C in the presence of magnesium bromide. At 80 °C, (1R,2S,5R)-menthyldiphenylgermane reacted with primary alkyl radicals with a rate constant of 1.02 × 10⁶ M⁻¹ s⁻¹. Kinetic studies reveal the Arrhenius expression for this reaction to be: log(k/M⁻¹ s⁻¹) = (11.1 ± 0.4) − (34.6 ± 3.1)/θ where θ=2.3RT kJ mol⁻¹.