Monitoring selected hydrogen bonds in crystal hydrates of amino acid salts: combining variable-temperature single-crystal X-ray diffraction and polarized Raman spectroscopy

Abstract

Predicting behaviour of hydrogen bonds with varying temperature, in particular-correlating donor-acceptor distances in the O-H···O hydrogen bonds with the frequencies of O-H stretching vibrations is important for understanding dynamics of biomolecules and phase transitions in crystals. A commonly used correlation suggested earlier in the literature is based on statistical analysis of different compounds [A. Novak, Structure and Bonding, 1974, 18, 177; K. Nakamoto, M. Margoshes, R. E. Rundle, J. Am. Chem. Soc., 1955, 77, 6480]. The present study is a rare example when correlations between geometry and energy parameters have been found for selected individual hydrogen bonds in the same crystalline compound at multiple temperatures. The properties of several types of O-H···O hydrogen bonds in bis(DL-serinium) oxalate dihydrate and DL-alaninium semi-oxalate monohydrate have been studied by a combination of variable-temperature single-crystal X-ray diffraction and polarized Raman spectroscopy. The changes in the hydrogen bonds geometry could be compared with the changes of the corresponding spectral modes. The correlation suggested by Novak is roughly followed, better for medium and weak, than for short hydrogen bonds. Fine details of spectral changes differ for individual bonds. The way how H-bonds are affected by cooling depends on their environment in the crystal structure. Short O-H···O hydrogen bonds in bis(DL-serinium) oxalate dihydrate expand or remain almost unchanged on cooling, whereas in DL-alaninium semi-oxalate monohydrate all strong H-bonds are compressed under these conditions. The distortion of individual hydrogen bonds on temperature variations is correlated with the anisotropy of lattice strain.

Molecular ferroelectric pyridin-2-ylmethanaminium perchlorate with phase transition induced by disorder of perchlorate

“…The vibration at 628 cm À1 comes from the inplane deformation of the perchlorate anion. 16,36 By varying temperature, Raman peak position shis before and aer the phase transition at 628 cm À1 (Fig. S2 †), it can also be seen that the perchloric acid disorder changes before and aer the phase transition.…”

Novel paste electrodes based on phosphonium salt room temperature ionic liquids for studying the redox properties of insoluble compounds

“…It should be noted though that for O O contacts so short as 2.45 Å, the OH group, in case of its presence in the complex, would produce the IR band at extremely low frequencies of ca. 500-1000 cm −1 [82,83], where it could be easily masked by the IR bands of skeletal vibrations. The oxidation state of the iron cation was confirmed by ESR (Fig.…”

Low-temperature phase transition in glycine–glutaric acid co-crystals studied by single-crystal X-ray diffraction, Raman spectroscopy and differential scanning calorimetry

“…7e), mainly because of the similar donor-acceptor distances in different hydrogen bonds. Therefore, it was not possible to follow the vibrations of selected individual hydrogen bonds and to correlate their temperature dependences with changes in the interatomic distances, as has been done for some other amino acid salts (Zakharov et al, 2011).…”