Solid-solid phase transitions in DL-norvaline studied by differential scanning calorimetry and Raman spectroscopy.
J Phys Chem B
; 114(3): 1294-300, 2010 Jan 28.
Article
in En
| MEDLINE
| ID: mdl-20043648
ABSTRACT
The structural modifications of the amino acid DL-Norvaline have been studied using differential scanning calorimetry (DSC) and Raman spectroscopy. DSC results showed that this amino acid undergoes two solid-solid phase transitions at -116.9 and -76.1 degrees C in the temperature range -130 to +300 degrees C. Raman spectroscopy was applied to complement DSC results. The combination of the two methodologies point out that the observed phase transitions correspond to an increment of disordering in the aliphatic side chain of amino acid, an augmentation of the rotational motion of the amino group and a decrease of the strength of the intramolecular hydrogen bonding of the initial dimers at low temperatures. The observed phase transitions of DL-norvaline are compared with those found in DL-norleucine.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Valine
/
Molecular Conformation
Language:
En
Journal:
J Phys Chem B
Journal subject:
QUIMICA
Year:
2010
Document type:
Article
Affiliation country:
Greece