H-2 NMR relaxation and line shape analysis of water in a lamellar liquid crystalline phase formed by dodecyldimethylamineoxide (DDAO) and (H2O)-H-2
2001 (English)In: JOURNAL OF PHYSICAL CHEMISTRY B, ISSN 1520-6106, Vol. 105, no 50, 12524-8 p.Article in journal (Refereed) Published
Present study combines NMR relaxation and line shape analysis for heavy water in the lamellar liquid crystalline phase of DDAO/(2)-H2O, NMR spin-lattice, spin-spin relaxation times and the quadrupole splitting are measured at two temperatures and three different water contents in the hydration regime. A molecular picture of water hydration of the DDAO/(2)-H2O interface is extracted, which indicates a much more rapid water translational diffusion along the detergent interface, as compared to phospholipid interfaces. The local order and dynamics of the bound water are, however, not changing much between the two interfaces. This indicates, that local interactions of water with the headgroup are not much dependent on the actual phase or detergent system. This work also presents clear experimental evidence for a dip at the magic angle of the H-2 powder spectrum, as theoretically predicted. Raising the temperature removes this observed dip at the isotropic frequency. This corresponds to an increase in the correlation time tau (c) from 8.5 ns at 25 degreesC to 20 ns at 55 degreesC, where tau (c) is related to translational dynamics of water along the detergent/water interface. However, this counter-intuitive increase in tau (c) with temperature may be interpreted as a reorganization of water at the interface, as is further supported by increasing quadrupolar splittings with increasing temperature.
Place, publisher, year, edition, pages
2001. Vol. 105, no 50, 12524-8 p.
IdentifiersURN: urn:nbn:se:umu:diva-8676DOI: doi:10.1021/jp0119577OAI: oai:DiVA.org:umu-8676DiVA: diva2:148347