title: Influence of solvent and salt concentration on the alignment properties of acrylamide copolymer gels for the measurement of RDC.
abstract: The dependence of molecular alignment with solvent nature and salt concentration has been investigated for mechanically stretched polyacrylamide copolymer gels. Residual dipolar couplings (RDCs) were recorded for D(2)O, DMSO-d(6), and DMSO-d(6)/D(2)O solutions containing different proportions of the solvents and different sodium chloride concentrations. Alignment tensors were determined by fitting the experimental RDCs to the DFT-computed structure of N-methylcodeinium ion. Analysis of the tensors shows that the degree of alignment decreases with the proportion of DMSO-d(6) as well as with the concentration of sodium chloride, most likely due to enhanced ion-pair aggregation. Furthermore, rotation of the alignment tensor is observed when increasing the salt concentration.
authors.affiliation: Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares, Universidade de Santiago de Compostela, Campus Vida, 15782, Santiago de Compostela, Spain
authors.forename: Pablo
authors.initials: P
authors.lastname: Trigo-Mouriño
authors.forename: Armando
authors.initials: A
authors.lastname: Navarro-Vázquez
authors.forename: Víctor M
authors.initials: VM
authors.lastname: Sánchez-Pedregal
mesh_terms: D020106:Acrylamide / Q000737:chemistry*; D000465:Algorithms; D017666:Deuterium Oxide / Q000737:chemistry; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D005782:Gels / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular; D011108:Polymers / Q000737:chemistry*; D011789:Quantum Theory; D012965:Sodium Chloride / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry
chemical_list: D005782:Gels; D011108:Polymers; D012997:Solvents; D020106:Acrylamide; D012965:Sodium Chloride; D017666:Deuterium Oxide; D004121:Dimethyl Sulfoxide