M.K. Marchewka

Fourier transform IR and Raman spectroscopy and structure of carbohydrates

Abstract To determine the role of the skeletal base configuration of carbohydrate molecules, a comparative study was made, using IR and Raman spectroscopy, of theoretical calculations of the vibrational spectra of a series of carbohydrates differing in the configuration of CO (CH) bonds in various positions of the pyranose ring. The normal vibrations of carbohydrate molecules have, with few exceptions, close or coinciding frequencies; however, they differ greatly in the shape and contribution to the potential energy distribution (PED) of individual groups and bonds. Despite the cooperative character of the vibrations, each compound is characterized by a specific set of frequencies with a prevailing contribution to the PED of particular CO and CC bonds of the molecule. It is concluded that vibrations have a peculiar localization and that steric factors play an important role in the vibrational spectra of carbohydrates.

Crystal structure, vibrational spectra and nonlinear optical properties of L-histidinium-L-tartrate hemihydrate

Abstract Single crystals of a new L -histidinium salt: L -histidinium L -tartrate hemihydrate, [(C 3 H 4 N 2 ) + C 3 H 6 NO 2 ]·(C 4 H 5 O 6 ) − ·0.5H 2 O, were obtained by slow evaporation of an aqueous solution at room temperature. The compound crystallises in a non-centrosymmetric space group of the monoclinic system. The L -histidine molecule occurs in the zwitterion form, with additional protonation of the N(3) ring atom, while the tartaric acid is singly ionised with one COO − carboxylate group. The vibrational spectra are in full agreement with the structure obtained from X-ray crystallography. The salt is a good second harmonic generator: the SHG efficiency was measured as d eff =0.79 d eff (KDP).

Crystal structure, vibrational spectra and nonlinear optical properties of tetrakis(2,4,6-triamino-1,3,5-triazin-1-ium) bis(selenate) trihydrate crystal

Abstract X-ray single crystal diffraction and the vibrational spectroscopic analysis of a new melaminium salt, tetrakis(2,4,6-triamino-1,3,5-triazin-1-ium) bis(selenate) trihydrate, (C3H7N6+)4·(SeO42−)2·3H2O, is reported. The compound crystallizes in the non centrosymmetric space group of triclinic system. Second harmonic generation efficiency deff=0.4deff(KDP). Intense hydrogen-bonded network is present in the crystal structure of the complex with notable vibrational effects.

Structural physico-chemistry of cellulose macromolecules. Vibrational spectra and structure of cellulose

Abstract By the methods of Fourier transform infrared and Raman spectroscopy and theoretical conformational analysis, the conformational peculiarities of macromolecules of cellulose of various structural modifications have been studied. It has been shown that celluloses of structural modifications I, II and III differ in rotary isomerism of elementary links (form of macromolecules), rotamers of C6H 2 OH groups as a consequence of rotations around C5C6 and C6O6 bonds and system of intra- and intermolecular hydrogen bonds. The results obtained are of great importance for the development of a new scientific direction—structural physico-chemistry of cellulose macromolecules which consists in the establishment of interrelationship between the physical structure and conformational properties of macromolecules determined by their chemical structure and intra- and intermolecular interactions.

Vibrational spectra and the structure of medical biopolymers

Abstract The authors are making systematic studies of the main kinds of polysaccharides and proteins by Fourier transform infrared (FTIR) and Raman (FTR) spectroscopy. In this publication some new results directly related to medical practice and structural physico-chemistry of biopolymers are presented.

Structure and polarized IR and Raman spectra of Na2SeO4·H2SeO3·H2O crystal

Abstract Na 2 SeO 4 ·H 2 SeO 3 ·H 2 O crystals are orthorhombic, space group Cmc 2 1 , with α=9.615(6)A, b =11.193(12)A, c =9.615(10)A and Z =4. The crystal structure was determined from three-di- mensional X-ray diffraction data taken on an automatic diffractometer with MoKa radiation and refined by least-squares techniques to R =0.049 for 775 non-zero reflections. The selenate anions and selenious acid molecules occupy C s , sites and form infinite chains through hydrogen bonds with an O⋯O distance of 2.622(15)A. Water molecules of C s symmetry are attached to the selenious acid molecules by weak hydrogen bonds with an O⋯O distance of 2.957(25)A. The second proton (H (61)) of the water molecule interacts with two pairs of oxygen atoms belonging to the neighbouring chains. The stretching vibration of the strong hydrogen bonds (2.622 (15)A) shows a characteristic feature containing two strong bands at ≈ 2800 cm −1 (A) and 2400 cm −1 (B) and a very weak band at ≈ 1500 cm −1 (C), appearing in both IR and Raman spectra. The frequencies of the A and B bands are different in the IR spectra for the X( a ) and Z( c ) polarizations as well as in the polarized Raman spectra. This is due to a strong interaction /coupling between the νOH vibrations of the nearest hydrogen bonds in the same chain. The transition dipole moment of the νOH is almost parallel to the Se(1)⋯Se(2) direction. The δOH vibration gives bands in the region 1300- 1260 cm −1 , while γOH appears at ≈ 790 cm −1 . The internal vibrations of the selenate anions and selenious acid molecules are discussed in terms of a site and factor group effect. An assignment of their bands is proposed in terms of the approximate type of motions using the “oriented gas” model approach. The stretching vibrations of the water molecules appear, in fact, to be stretching vibrations of the hydrogen bonds. It is spectroscopically proved that the H (61) protons of water molecules interact with as many as four ozygens.

X-ray, phase transition, IR and Raman studies of the solid complex of bis(pyridine betaine)-sulphuric acid

Abstract Crystals of bis(pyridine betaine)-sulphuric acid complex are monoclinic, space group C2/c, a =12.464(2) A, b =10.771(2) A, c =12.541(3) A, β =101.20(3)°. The SO 4 2− group is located on a twofold axis and forms an U-shaped system, bridged by two short and identical H-bonds, with two protonated betaine molecules (O···O distances 2.472(7) A and O–H···O angle 165°). The solid state FTIR spectrum of the complex shows a carbonyl band at ca. 1722 cm −1 and a broad absorption extending from ca. 2800 down to 400 cm −1 . On deuteration the broad absorption shifts slightly to lower frequencies and the isotope ratio of the centre of gravity of the total absorption in the 2800–400 cm −1 region is υ ′ H / υ ′ D =1.07. The frequencies of the narrow skeletal vibration from the broad absorption were subtracted using second-derivative spectroscopy. The I and II order phase transitions were found by DSC method.

Growth and characterization of Melaminium bis (trichloroacetate) dihydrate.

Single crystals of melaminium bis (trichloroacetate) dihydrate have been grown successfully by slow evaporation solution growth technique at room temperature. Single crystal X-ray diffraction analysis reveals that the compound crystallizes in monoclinic system with non -centrosymmetric space group C2 with lattice parameters a=17.70 Å, b=8.44 Å, c=6.09 Å, α=90°, β=100.24°, γ=90° and V=900 (Å)3. The UV-Vis transmittance spectrum shows that the crystal has a good optical transmittance in the entire visible region with lower cutoff wavelength of 351 nm. The vibrational frequencies of various functional groups present in the crystal have been derived from FI-IR, FT-Raman and Confocal Raman analyses. The chemical structure of the compound was established by 1H and 13C NMR spectrum. TGA-DTA analysis reveals that the materials have good thermal stability and the melting point of the crystal is found to be 195°C. The dielectric response of the crystals was studied in the frequency range 50 Hz to 5 MHz at different temperatures and the results are discussed. Etching studies show the growth pattern of the crystals. The second harmonic generation efficiency was measured in comparison with KDP by employing powder Kurtz method.

Polarised FTIR and Raman spectra of betaine phosphite single crystal I. Paraelectric phase

Abstract Polarised IR and Raman spectra of the betaine phosphite (BPI = Betaine-H 3 PO 3 ) single crystals were measured at room temperature (paraelectric phase). The assignment of the bands is proposed on the basis of the oriented gas model approximation. The stretching vibrations ( v OH) of the hydrogen bonds give strong absorption extending from ca. 3000 cm −1 to 500 cm −1 in the IR spectra polarised parallel to the ferroelectric b(Z) axis (0(4)H(13)...0(4′) (PP2) hydrogen bond) and parallel to the X axis (0(2)H(12)...0(3) (BP) and 0(6)H(15)...0(6′) (PP1)) hydrogen bonds). Those absorptions show characteristic ABC structure with quite weak the A bands. The C bands (ca. 1600 cm − ) correspond to the fundamental νOH vibrations. The stretching vibrations of the PO bonds in the phosphite anions show unusual properties which may be explained either by strong coupling with the vibrations (stretching v OH and out-of-plane bending γOH) of the hydrogen bonds or by the disorder of the protons in the inter-phosphite (PP1 and PP2) hydrogen bonds. The betaine molecules are in the form of cations ((CH 3 ) 3 N + CH 2 COOH). Some internal vibrations ( v C=O, v s C 3 N) strongly interact with the stretching vibrations of the hydrogen bonds. Broad scattering (the broad wing of the Rayleigh line) is observed in the Raman spectrum X(zz)Y below 200 cm −1 . It originates either from a low wavenumber overdamped mode or from the disordering in the paraelectric phase.

Fourier transform Raman study of electrochromic crystalline hydrate films WO3·1/3(H2O)

Evolution of the vibrational spectra of electrochromic thin films WO3·1/3(H2O) during coloration-bleaching process has been studied by Fourier Transform Raman Spectroscopy. It is shown that protons or deuterons inserted into the film during the electrochromic coloration do not play only passive role of charge compensators but strongly distort the film lattice as well. The lattice distortion is reversible during bleaching process up to the charge density of 30 mC/cm2. For the larger coloration density the strong enhancement of Raman effect was observed.