title: Diarmed (adamantyl/alkyl) surfactants from nitrilotriacetic acid.
abstract: The compounds presented here constitute a clear example of molecular biomimetics as their design is inspired on the structure and properties of natural phospholipids. Thus novel double-armed surfactants have been obtained in which nitrilotriacetic acid plays the role of glycerol in phospholipids. The hydrophobic arms are linked to the head group through amide bonds (which is also the case of sphingomyelin): (R1NHCOCH2)(R2NHCOCH2)NCH2CO2H (R1 being CH3(CH2)11, CH3(CH2)17, CH3(CH2)7CHCH(CH2)8, and adamantyl, and R2=adamantyl). The dependence of the surface tension with concentration shows the typical profile of surfactants since a breaking point, which corresponds to the critical aggregation concentration (cac), is observed in all cases. The cac of these diarmed derivatives are about 1-3 orders of magnitude lower than those of classical monoalkyl derivatives used as reference compounds. In contrast to conventional surfactants, reversed trends in cac values and molecular areas at the solution-air interface have been observed. This anomalous behavior is tied to the structure of the surfactants and suggests that long and flexible alkyl chains should self-coil previous to the aggregation or adsorption phenomena. Above cac all compounds form large aggregates, globular in shape, which tend to associate forming giant aggregates.
authors.affiliation: Departamento de Química Física, Facultad de Ciencias, Universidad de Santiago de Compostela, Avda. Alfonso X El Sabio s/n, 27002 Lugo, Spain. Electronic address: juanventura.trillo@usc.es.
authors.forename: Juan V
authors.initials: JV
authors.lastname: Trillo
authors.affiliation: Departamento de Química Física, Facultad de Ciencias, Universidad de Santiago de Compostela, Avda. Alfonso X El Sabio s/n, 27002 Lugo, Spain. Electronic address: jose.vazquez@usc.es.
authors.forename: José
authors.initials: J
authors.lastname: Vázquez Tato
authors.affiliation: Departamento de Química Física, Facultad de Ciencias, Universidad de Santiago de Compostela, Avda. Alfonso X El Sabio s/n, 27002 Lugo, Spain. Electronic address: aida.jover@usc.es.
authors.forename: Aida
authors.initials: A
authors.lastname: Jover
authors.affiliation: Departamento de Química Física, Facultad de Ciencias, Universidad de Santiago de Compostela, Avda. Alfonso X El Sabio s/n, 27002 Lugo, Spain. Electronic address: santiagodefrutos@hotmail.com.
authors.forename: Santiago
authors.initials: S
authors.lastname: de Frutos
authors.affiliation: Escuela de Química, Centro de Investigación en Electroquímica y Energía Química (CELEQ), Universidad de Costa Rica, San José, Costa Rica. Electronic address: susyhug24@yahoo.com.
authors.forename: Victor H
authors.initials: VH
authors.lastname: Soto
authors.affiliation: Department of Chemistry, "Sapienza" University of Rome, P. le A. Moro 5, 00185 Rome, Italy. Electronic address: luciano.galantini@uniroma1.it.
authors.forename: Luciano
authors.initials: L
authors.lastname: Galantini
authors.affiliation: Departamento de Química Física, Facultad de Ciencias, Universidad de Santiago de Compostela, Avda. Alfonso X El Sabio s/n, 27002 Lugo, Spain. Electronic address: francisco.meijide@usc.es.
authors.forename: Francisco
authors.initials: F
authors.lastname: Meijide
mesh_terms: D032701:Biomimetics / Q000379:methods*; D009571:Nitrilotriacetic Acid / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D013501:Surface-Active Agents; D009571:Nitrilotriacetic Acid
keywords: Adamantyl/alkyl surfactant; Diarmed surfactant; Equilibrium area at the interface; Molecular biomimetics; Nitrilotriacetic head group; Surfactant synthesis