Addition of hydrophilic and lipophilic compounds of biological relevance to the monoolein/water system II - 13C NMR relaxation study.
The addition of hydrophilic and hydrophobic molecules to the 1-monooleoyl glycerol (MO)/water (W) system has been investigated at a molecular level by 13C nuclear magnetic resonance (NMR) relaxation. Depending on the nature of the additive, the liquid crystalline phases of the MO/W binary system are modified. The 13C NMR spin lattice relaxation rates of the various MO carbons were determined in the presence of the additives for different types of L(2) and liquid crystalline phases. Data revealed that local dynamics are independent of type and amount of additive (within 5 wt.%), and also of the type of the structural arrangement. The curvature of the interface does not affect the local mobility of MO carbons, with the exception of the glycerol G3 and the carboxylic C1 carbons. Moreover, the presence of the double bond in the mid part of the hydrocarbon chain induces a levelling in the relaxation rates on the neighboring carbons. The 13C NMR spin lattice relaxation rates at two magnetic field strengths and the Overhauser enhancement were measured in the L(2) phase of the MO/W/sodium decanoate system. The use of a two-step model of relaxation allowed to estimate order parameters, and slow and fast motions of MO in the structured aggregate.
Murgia
S
S
Dipartimento Scienze Chimiche, Universita' di Cagliari, Cittadella Universitaria Monserrato, S.S. 554 Bivio Sestu, 09042, Monserrato-Cagliari, Italy.
Caboi
F
F
Monduzzi
M
M
D005782:Gels / Q000737:chemistry; D005989:Glycerides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D014867:Water / Q000737:chemistry*
D005782:Gels; D005989:Glycerides; D014867:Water; C005953:monoolein