The dehydration process in the DL-phenylglycinium trifluoromethanesulfonate monohydrate crystal revealed by XRD, vibrational and DSC studies.

Thermal analysis, X-ray diffraction and temperature-dependent IR spectroscopy were used to study the dehydration process of crystalline DL-phenylglycinium trifluoromethanesulfonate monohydrate (PGTFH), CHNO·CFSO·HO. PGTFH dehydrates in one step centred at 353 K and crystallizes in the monoclinic space group C2/c, whereas the anhydrous compound (PGTF) crystallizes in the triclinic space group P-1. The dehydration process in PGTFH is preceded by a weakening of both the noncovalent aromatic-aromatic interactions and the packing contacts.

Different β-alanine dimeric forms in trifluoromethanesulfonic acid salts. XRD and vibrational studies.

Two new crystalline salts: β-alaninium trifluoromethanesulfonate (β-AlaOTf) and bis(β-alanine) trifluoromethanesulfonate (β-2AlaOTf) were obtained. The former one contains diprotonated β-alanine dimer, the latter one monoprotonated β-alanine dimer. Both compounds were studied by single crystal XRD, vibrational (IR and Raman) spectroscopy and calorimetric method.

Vibrational, XRD and (13)C NMR studies of DL-phenylglycinium methanesulfonate crystal.

A new crystal formed by DL-phenylglycine and methanesulfonic acid (PGLYMS) was obtained and studied by X-ray diffraction, IR and Raman spectroscopy, solid state NMR and DSC methods. Additionally, theoretical computations for the phenylglycine cation were carried out (DFT/B3LYP/aug-cc-pVDZ). Our results show that PGLYMS does not exhibit any phase transitions and crystallizes in the P21/c space group of monoclinic system (Z=4).

Phase transitions in non-centrosymmetric pyridinium trifluoromethanesulfonate crystal: Vibrational studies.

Infrared spectroscopy (4000-400 cm(-1)) in the wide temperature range, from 11 to 473 K, has been used to investigate the non-centrosymmetric pyridinium trifluoromethanesulfonate crystal, exhibiting several phase transitions. The assignments of the bands observed in the studied spectra have been proposed. The temperature dependence of the wavenumbers and the full width at half maximum (FWHM) of the bands arising from some internal vibrations of the pyridinium cation and the triflate anion have been analyzed in order to achieve a knowledge of whether these both ions are involved in the phase transitions and what is the role of these both ions in these phase transitions.

Experimental evidence on interaction between xenon and bovine serum albumin.

Xenon gas interacts with bovine serum albumin (BSA) dissolved in a physiological buffer solution. The fluorescence quenching related to the Trp emission is reversible and depends linearly on the time of saturation by Xe. The most probable site of this interaction is Trp212.

Participation of xenon guest in hydrogen bond network of β-hydroquinone crystal.

In the β-hydroquinone (β-HQ)-Xe crystal, the Xe guest is placed between two hexagonal rings of coupled [···O-H···O-](6) H-bonds. This clathrate is treated as the model for monitoring the H-bonding system with the Xe participation. Three kinds of isotope effects due to the H/D substitution in the [···O-H···O-](6) bonds are considered: (i) structural changes in the clathrate (X-ray diffraction), (ii) variations of (129)Xe NMR signal of the guest (CP MAS), and (iii) variations of selected vibrations of the host (IR).

Polarised vibrational spectra of betaine ortho-phosphoric acid complex. Part II. Phase transitions studies.

Polarised infrared transmission and Raman spectra of betaine ortho-phosphoric acid crystal in temperature ranges 13-393 and 13-300 K, respectively are reported and discussed in relation to phase transitions: antiferrodistortive at T(c1) = 365 K and antiferroelectric at T(c3) = 81 K. The spectra are consistent with unit cell doubling below T(c3). The participation of all hydrogen bonds apparent in the crystal in the antiferroelectric phase transition was shown.