Tatiana V. Laptinskaya

Interference of Raman and parametric processes in small angle scattering

Abstract Angular spectra of light scattering by polaritons are discussed. The angular line shape in the case of interference between Raman and parametric processes is considered. It is shown that the angular line shape can be used for calculation of complex dielectric function ϵ and complex quadratic susceptibility χ at a given polariton frequency. The proposed method is used for measuring dispersion curves of Re χ, Im χ and Im ϵ for lithium-natrium formate crystal at frequencies 3000–3700 cm -1 .

Two-phonon excitations in α-HIO3 polariton spectra

Abstract Parametric scattering spectra in piezoelectric iodic acid and deutered iodic acid monocrystals at frequencies 840…5000cm−1are discussed. For some of the second-order vibrations dynamical parameters are calculated. A few vibrations are related and their influence on optical properties of crystals is determined.

Differences in reactivity of N -acetyl- and N,N -diacetylsialyl chlorides caused by their different supramolecular organization in solutions

O-Sialylation of a substituted indolin-3-one under phase-transfer catalysis conditions, which does not occur when N-acetylsialyl chloride is used, proceeds with N,N-diacetylsialyl chloride as the glycosyl donor. A study using dynamic light scattering of solutions of both sialyl chlorides under conditions close to the conditions used for glycosylation showed a difference in the correlation radii of light scattering particles in such solutions. This suggests that the introduction of an additional N-acetyl group into the sialyl chloride significantly alters the structure of the supramers of glycosyl donor, which apparently have an increased accessibility of individual molecules for the attack by a nucleophile, which increases its reactivity.

Influence of hydrogen bonds on the colloidal and fluorescent properties of detonation nanodiamonds in water, methanol and ethanol

ABSTRACT This paper presents the results of research of influence of hydrogen bonds with different strength on fluorescence and colloidal properties of detonation nanodiamonds with surface carboxylic groups in the solvents. It is established that the colloidal properties of detonation nanodiamonds are almost independent on hydrogen bonds strength in water, methanol and ethanol. The fluorescent properties of detonation nanodiamonds are dependent on the type of solvent: the more intensive fluorescent properties correspond to weaker hydrogen bonds in solvents.

The use of the novel glycosyl acceptor and supramer analysis in the synthesis of sialyl-α(2–3)-galactose building block

A new glycosyl acceptor to be used in sialylation was designed as a 3-hydroxy derivative of 4-methoxyphenyl β-d-galactopyranoside with 2-O-acetyl group and O-4 and O-6 protected as benzylidene acetal. Two alternative syntheses of this compound were compared. Sialylation of 3-OH group of the glycosyl acceptor with O-chloroacetylated N-trifluoroacetylneuraminic acid phenyl thioglycoside (NIS, TfOH, MeCN, MS 3 Å, -40 °C) was studied in a wide concentration range (5-150 mmol L-1). The outcome of sialylation generally followed the predictions of supramer analysis of solutions of sialyl donor in MeCN, which was performed by polarimetry and static light scattering and revealed two concentration ranges differing in solution structure and the structures of supramers of glycosyl donor. The optimized conditions of sialylation (C = 50 mmol L-1) were used to synthesize protected Neu-α(2-3)-Gal disaccharide (78%, α:β = 13:1), which was then converted to sialyl-α(2-3)-galactose imidate building block useful for the synthesis of complex sialo-oligosaccharides.

Raman scattering by non-ordinary polaritons in orthorhombic crystal

In this article we consider features of intensity distribution of the Raman scattering by non-ordinary polaritons in the frequency - wavevector coordinates. The most simple instances of scattering in the crystallographic symmetry plane of an orthorhomibic crystal are described to illustrate the main different between nonordinary polaritons spectra and ordinary ones. It is supposed that a polariton wavevector orientation is constant for each spectrum. We discuss also the actual experimental situation with scattering by polaritons in (alpha) -iodic acid crystal near the frequency of the valency OH-bond taken as an example.

Nonlinear response function for anisotropic polaritons in an orthorhombic crystal

In this article we consider the intensity distribution of the light scattering by anisotropic (nonordinary) polaritons in the wave number--wave vector coordinates. We propose formulae for polariton spectra numerical calculation which are adequate for any wave vector direction and for resonant and nonresonant frequency areas. The case of polariton branch splitting along the wave vector coordinate when this vector directs close to optical axis of orthorhombic crystal is discussed as an illustration of the method availability.