Thermodynamic Properties of Ternary Ionic Liquid Mixture Containing a Common Ion: Excess Molar Volumes,Excess Isentropic Compressibilities,Excess Molar Enthalpies and Excess Heat Capacities

In the present investigations, the excess molar volumes, \( V_{ijk}^{\text{E}} \), excess isentropic compressibilities, \( \left( {\kappa_{S}^{\text{E}} } \right)_{ijk} \), and excess heat capacities, \( \left( {C_{p}^{\text{E}} } \right)_{ijk} \), for ternary 1-butyl-2,3-dimethylimidazolium tetrafluoroborate (i) + 1-butyl-3-methylimidazolium tetrafluoroborate (j) + 1-ethyl-3-methylimidazolium tetrafluoroborate (k) mixture at (293.15, 298.15, 303.15 and 308.15) K and excess molar enthalpies, \( \left( {H^{\text{E}} } \right)_{ijk} \), of the same mixture at 298.15 K have been determined over entire composition range of x _i and x _j . Satisfactorily corrections for the excess properties \( V_{ijk}^{\text{E}} \), \( \left( {\kappa_{S}^{\text{E}} } \right)_{ijk} \), \( \left( {H^{\text{E}} } \right)_{ijk} \) and \( \left( {C_{p}^{\text{E}} } \right)_{ijk} \) have been obtained by fitting with the Redlich–Kister equation, and ternary adjustable parameters along with standard errors have also been estimated. The \( V_{ijk}^{\text{E}} \), \( \left( {\kappa_{S}^{\text{E}} } \right)_{ijk} \), \( \left( {H^{\text{E}} } \right)_{ijk} \) and \( \left( {C_{p}^{\text{E}} } \right)_{ijk} \) data have been further analyzed in terms of Graph Theory that deals with the topology of the molecules. It has also been observed that Graph Theory describes well \( V_{ijk}^{\text{E}} \), \( \left( {\kappa_{S}^{\text{E}} } \right)_{ijk} \), \( \left( {H^{\text{E}} } \right)_{ijk} \) and \( \left( {C_{p}^{\text{E}} } \right)_{ijk} \) values of the ternary mixture comprised of ionic liquids.     

Excess heat capacities and excess molar enthalpies of the mixtures containing tetrahydropyran,piperidine and cyclic alkanones

Journal of Thermal Analysis and Calorimetry - In the present study, molar heat capacities, $$\left( {C_{\text{P}}^{{}} } \right)_{123}$$ , at T/K = 293.15–308.15 K...     

Reactions of [Mn2(μ-pyS)2(CO)6] with bidentate N-donor ligands: Crystal structure of [Mn(η1-pyS)(bipy)(CO)3] (bipy = 2,2′-bipyridyl, pySH = pyridine-2-thiol)

The dimeric complex [Mn₂(-pyS)₂(CO)₆] (1) reacted with 2 equivalents of 2,2-bipyridyl (bipy), 1,10-phenanthroline (phen), and ethylenediamine (en) to give the corresponding monomeric complexes [Mn(¹-pyS)(bipy)(CO)₃] (2), [Mn(¹-pyS)(phen)(CO)₃] (3), and [Mn( ¹-pyS)(en)(CO)₃] (4). The pyS ligand in these complexes acts as a monodentate, two-electron donor ligand, which coordinates to manganese through the sulfur atom. This is confirmed by an X-ray structure determination of 2, which contains two structural isomers in the asymmetric unit. Crystals of this compound are the monoclinic, space group P2 ₁/c, a = 21.593(4), b = 10.463(2), c = 16.385(3) Å, = 102.468(13)°, V = 3614.5(12) ų, and Z = 8. The three CO groups are facially distributed in both isomers, but the relative positions of the pyS and bipy ligands are different.     

X-ray structure of [(μ-H)Os3(CO)10(μ-1,8-η2-C9H6N)]

Decacarbonyl--hydrido--1,8-²-quinoline-triosmium crystallizes in the triclinic space group P with a = 7.8551(6), b = 9.1283(8), c = 16.7915(8) Å, = 74.788(2), = 88.086(2), = 66.392(3)°, V = 1062.22(13)° ų, T = 150 K, and Z = 2. The molecule consists of an Os₃ triangle with the hydride and the heterocyclic ligand bridging the same Os—Os edge. The heterocyclic ligand is coordinated through the C(8) carbon and nitrogen atoms in a new -1,8-²-bonding mode. The Os—Os distances lie in the close range 2.8837(4)–2.9034(4) Å with an average value of 2.892(7) Å.     

Simultaneous Controllability of PSD and MWD in Emulsion Polymerisation

A sensitivity study of particle size distribution (PSD) and molecular weight distribution (MWD) responses to perturbations in initiator, surfactant, monomer and chain transfer agent in a semi‐batch emulsion polymerisation is presented. The objective is to provide a systematic study on the ability to simultaneously control both PSD and MWD, towards inferential control of end‐use product properties. This would lead towards identification of the practical feasible regions of operability. All inputs appeared to have an intrinsic and simultaneous influence on end‐time PSD and MWD. Trends shown in experimental results have been explained in a mechanistic sense and also compared to simulation results from a combined PSD/MWD population balance model. The preliminary comparison between experiment and simulation highlights areas to be focussed on with respect to model improvement.

     

Selective binding of L-glutamate derivative in aqueous solvents

A chiral bisguanidinium macrocycle binds N-Boc-L-glutamate in a 1 : 1 stoichiometry with significant selectivity in competitive solvent (DMSO-H(2)O).     

Permanganate transfer and reduction by D‐glucose in benzene–cetyltrimethylammoniumbromide aqueous solution: A kinetic study

The addition of cationic surfactant, cetlytrimethylammoniumbromide (CTAB), in benzene and aqueous potassium permanganate solution brought the MnO from the aqueous phase to the organic phase. At 525 nm, the absorbance of the organic phase increased until it reached a maximum, and then decreased with [CTAB]. The effect of [CTAB] on the reduction of permanganate by D ‐glucose in a benzene–CTAB system has been studied spectrophotmetrically. The observed effect on the rate constant is catalytic up to a certain concentration of CTAB; thereafter, a saturation phenomenon is observed with an increased concentration of CTAB. The oxidation reaction obeyed the first‐order kinetics with respect to the D ‐glucose. On addition of H₂SO₄, there was a decrease in the rate constants. There is evidence for the existence of manganese as a water‐soluble colloidal MnO₂. A detailed mechanism with the associated reaction kinetics is presented and discussed. © 2008 Wiley Periodicals, Inc. 40: 496–503, 2008     

Solid-state photochemical [2+2] cycloaddition in a hydrogen-bonded metal complex containing several parallel and crisscross C=C bonds

One-dimensional hydrogen-bonded complex [Zn(bpe)(2)(H(2)O)(4)](NO(3))(2).8/3 H(2)O.2/3 bpe (1, bpe=4,4'-bipyridylethylene) containing coordination complex cations [Zn(bpe)(2)(H(2)O)(4)](2+) with parallel and crisscross double bonds undergoes photochemical [2+2] cycloaddition in the solid state and produces tetrakis(4-pyridyl)cyclobutane (tpcb) in up to 100 % yield with rctt-tpcb (2a) as major and rtct-tpcb (2b) as minor product. The bpe ligands with crisscross conformation of C=C bonds appear to undergo pedal-like motion prior to photodimerization. Grinding single crystals to powder accelerates the pedal motion of crisscrossed olefins in the bpe ligands to parallel alignment and provides the rctt-cyclobutane stereoisomer 2a quantitatively. In addition, 100 % photodimerization of ground 1 indicates that the free bpe ligands, which are remote from each other in a pool of water, and NO(3)(-) ions moved toward each other to give a mixture of rctt- and rtct-tpcb isomers.     

Towards quantitatively reproducible substrates for SERS

There is a need for a method to facilitate the development of novel, reproducible colloidal surface-enhanced Raman scattering (SERS) substrates to encourage the use of SERS in applied studies. In this study we show for the first time that by using suitably designed SERS experiments in conjunction with multivariate analysis of variance (MANOVA), an objective assessment of colloidal SERS reproducibility can be made. This is demonstrated with the analyte cresyl violet, but could be extended to any analyte of interest for which reproducible SERS data are needed.     

New Epoxydammarane Triterpenes from Salvia santolinifolia

Three new 20,24‐epoxydammarane triterpenes, santolins A–C ( 1 – 3 ), were isolated from the AcOEt‐soluble fraction of the MeOH extract of Salvia santolinifolia (whole plant). Their structures were assigned based on ¹H‐NMR, ¹³C‐NMR (DEPT), and 2D‐NMR analyses, in combination with HR‐MS experiments and comparison with literature data of related compounds.