title: Monolayer properties of uronic acid bicatenary derivatives at the air-water interface: effect of hydroxyl group stereochemistry evidenced by experimental and computational approaches.
abstract: By screening uronic acid-based surfactant interfacial properties, the effect of the hydroxyl group stereochemistry (OH-4) on the conformation of bicatenary (disubstituted) derivatives at the air-water interface has been evidenced by experimental and computational approaches. Physical and optical properties of a monolayer characterized by Langmuir film balance, Brewster angle microscopy, and ellipsometry at 20 °C reveal that the derivative of glucuronate (C(14/14)-GlcA) forms a more expanded monolayer, and shows a transition state under compression, in the opposite to that of galacturonate (C(14/14)-GalA). Both films are very mechanically resistant (compression modulus > 300 mN m(-1)) and stable (collapse pressure exceeding 60 mN m(-1)), while that of C(14/14)-GalA exhibits a very high compression modulus up to 600 mN m(-1) like films in the solid state. Computational approaches provide single and assembly molecular models that corroborate the molecule expansion degree and interactions data from experimental results. Differences in the molecular conformation and film behaviours of uronic acid bicatenary derivatives at the air-water interface are attributed to the intra-H-bonding formation, which is more favourable with an OH-4 in the axial (C(14/14)-GalA) than in the equatorial position (C(14/14)-GlcA).
authors.affiliation: University of Liege, Gembloux Agro-Bio Tech, Passage des déportés 2, B-5030 Gembloux, Belgium. h.razafindralambo@ulg.ac.be
authors.forename: Hary
authors.initials: H
authors.lastname: Razafindralambo
authors.forename: Aurore
authors.initials: A
authors.lastname: Richel
authors.forename: Bernard
authors.initials: B
authors.lastname: Wathelet
authors.forename: Christophe
authors.initials: C
authors.lastname: Blecker
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Wathelet
authors.forename: Robert
authors.initials: R
authors.lastname: Brasseur
authors.forename: Laurence
authors.initials: L
authors.lastname: Lins
authors.forename: Jose
authors.initials: J
authors.lastname: Miñones
authors.forename: Michel
authors.initials: M
authors.lastname: Paquot
mesh_terms: D000388:Air; D006878:Hydroxides / Q000737:chemistry*; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D011312:Pressure; D013237:Stereoisomerism; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*; D014574:Uronic Acids / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D006878:Hydroxides; D013501:Surface-Active Agents; D014574:Uronic Acids; D014867:Water; C031356:hydroxide ion