Ultrasonic Broadband Spectrometry of Liquids A Research Tool in Pure and Applied Chemistry and Chemical Physics

This review is a survey of the many scientific applications of ultrasonic broadbandspectrometry (absorption and velocity measurements with coherent sound waves)in liquids and liquid systems, covering, at present, a frequency range from nearly10 kHz to 10 GHz. Ultrasonic spectrometry has proved to be an almost universalresearch tool in many laboratories, one that is useful for investigation of variouschemical, biochemical, and physicochemical systems. Sound waves traversingliquids induce periodic perturbations in pressure and temperature, which can shiftequilibria, resulting in characteristic sound absorption and velocity dispersionspectra. An analysis of such spectra yields valuable information about thermodynamic and kinetic parameters of the particular system that is often difficult toobtain by other methods. Since such periodic perturbations imposed on the systemare incremental in nearly all cases, the system can be studied under equilibriumconditions. All nonlinear effects (heating, nonconstant fluid compressibility, andothers) are negligible, permitting, for instance, the application of linearized rateequations. In this review, various examples of measured broadband spectra arepresented. Related elementary processes are discussed. Among these are ionicand molecular reactions, including mechanisms of association and complexation,proton transfer, solvation, isomerization, interconversion, side-group rotation,hydrogen-bonding, as well as stacking processes and micelle formation. Specialattention will be given to the extensive research on chemical relaxation.Fundamental early and recent publications are cited and discussed. Many referencesare included with particular emphasis on less well known research and publicationsfrom countries of the former USSR. This review aims at a demonstration of thewidespread applications of modern ultrasonic techniques in many fields ofliquid-state research.     

Observation of power-Law scaling for phase transitions in linear trapped ion crystals

We report an experimental confirmation of the power-law relationship between the critical anisotropy parameter and ion number for the linear-to-zigzag phase transition in an ionic crystal. Our experiment uses laser cooled calcium ions confined in a linear radio-frequency trap. Measurements for up to ten ions are in good agreement with theoretical and numeric predictions. Implications on an upper limit to the size of data registers in ion trap quantum computers are discussed.     

Expedient Conversion of Lactose into Versatile Derivatives of Lactosamine and β-d-Galactosyl-(1→4)-d-mannosamine

Abstract

A practical, nine-step protocol is described for the preparation of synthetically useful N-acetyllactosamine (LacNAc) derivatives as well as LacNAc itself from lactose using the benzoylated oxime of lactos-2-ulosyl bromide 2 as the key intermediate. All steps are performed with simple reagents, do not require chromatography, are large-scale adaptable and allow overall yields of 30%.     

Organoboronium amphiphilic block copolymers

A new class of amphiphilic organometallic block copolymers with cationic organoboron pendant groups was developed. Selective replacement of one of the bromine substitutents on each boryl group of the block copolymer PSBBr₂‐b‐PS with an organometallic reagent ArM (ArM = 2,4,6‐trimethylphenyl copper, 4‐t‐butylphenyltrimethyl tin) followed by treatment with 2,2′‐bipyridine gave the novel block copolymers [ 3Ar ](Br)_n as light yellow solid materials that show good stability in air and moisture and high solubility in most organic solvents. Their structure and composition were confirmed by multinuclear NMR, GPC, and elemental analysis. Highly regular micellar aggregates form in block‐selective solvents (e.g., MeOH, toluene) as demonstrated by ¹H NMR, dynamic light scattering, and transmission electron microscopy. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6612–6618, 2009     

PAN composite membrane with different solvent affinities controlled by surface modification methods

Polyacrylonitrile (PAN) composite membranes with surface properties designed by either a chemical modification with ethylenediamine (EDA), or layer‐by‐layer (LbL) polyelectrolyte adsorption were investigated in this paper. Fourier‐transformed infrared (FTIR) spectroscopy and streaming potential measurements showed that the first step of the reaction with EDA in gas phase was the formation of ammonium salts with the reactive carboxylic groups present on the surface of the starting membrane. Part of the ammonium carboxylate groups was transformed in secondary amide linkages by a heat‐induced reaction. Poly(sodium styrenesulfonate) (NaPSS) and a polycation containing about 95 mol % of N,N‐dimethyl‐2‐hydroxypropyleneammonium chloride units in the backbone (PCA₅) were used as opposite polyions in the LbL film construction. The adsorbed polyion amount per every layer was controlled by the nature and concentration of the supporting electrolyte in polyelectrolyte deposition solution (NaBr and KBr). An almost linear increase of the adsorbed polyion amount versus the layer pair number was observed. The swelling degree (SD) in pure alcohols of the LbL‐modified PAN composite membrane decreased with the increase of the solvent polarity and with the decrease of the pore volume by pore filling with polyelectrolyte complex multilayer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4161–4171, 2005