Complexes between β-Cyclodextrin and Aliphatic Guests as New Noncovalent Amphiphiles:  Formation and Physicochemical Studies

Abstract

The aim of this work was to develop new sugar nonionic surfactants from raw materials of plant origin. These nonionic surfactants are based on the noncovalent association between cyclodextrins (CDs) and fatty alcohols or fatty acids. We describe here (i) the preparation of various complexes between β-cyclodextrin (β-CD) and fatty alcohols or fatty acids, (ii) the evaluation of the surfactive properties of the complexes, and (iii) the structure of one of them which presents interesting surfactive properties. Among the prepared complexes, the β-CD/alcohol complexes present high surface tension efficiencies compared with β-CD/acid complexes. The surfactive properties of the β-CD/alcohol complexes are influenced by the length of the hydrocarbon chain and reach an excellent efficiency for guests having 10-12 carbon atoms. For the complex between β-cyclodextrin and undec-10-en-1-ol, the inclusion mode in aqueous solution was described by nuclear magnetic resonance techniques. The results showed a 1:1 stoichiometry and a dynamic process exchanging the two possible orientations of the guest relative to the β-CD.

Hydrogenated and Fluorinated Host–Guest Surfactants: Complexes of Cyclodextrins with Alkanes and Fluoroalkyl‐Grafted Alkanes

“…Two phases including excessive alkanes and clear aqueous phase without any precipitates were finally obtained on standing. Compared with the three phases of b-CD and long-chain alcohol with precipitates, [11] it showed that substituted CDs were able to enhance the solubility of complexes.…”

“…However, work dealing with the effect of reducing water surface tension, that is, the supramolecular surfactant indeed, are almost in blank. [10,11,12] CDs can include the hydrophobic part of surfactants and form various inclusion complexes. However, these CD/surfactant complexes usually exhibit no surface activity, [13] because the hydrophobic groups of surfactants are shielded by CDs.…”

“…[4,5] Although amphiphiles included by b-CD usually lose their unique amphiphilicity, [14] a peculiar counterexample is reported that high surface activity is observed in the solution of complexes of b-CD with undecenol and dodecanol. [11] In consideration of this structure containing a short hydrophobic tail and a large hydrophilic part but showing surface activity, and compared with the decreased surface activity of complexes of b-CD with corresponding long-chain acids in the same work, [11] it could be speculated that the long-chain Abstract: A novel type of surfactants named "host-guest surfactants" were designed and synthesized. The headgroup and hydrophobic tail of the new surfactants are connected by supramolecular interactions rather than covalent bonds.…”

“…11, [31,32] whereas modified b-CDs only form 1:1 complexes with these surfactants. [31,33] It has been suggested that the cavity of b-CD could accommodate eight CH 2 groups of the chain, [11,31,34] whereas for those modified b-CDs this maximum could be extended to 11-13, [33] when the chain coil through the formation of gauche kinks within the host cavity. [33] It should be noted that the occurrence of the headgroup made the neighboring CH 2 highly hydrated in the surfactant molecule and therefore a longer chain length of the surfactants could be stabilized by CDs in solution than that of alkA C H T U N G T R E N N U N G anes for the same 1:1 stoichiometry.…”

Self-Aggregation and Solubilizing Properties of the Supramolecular System Based on Azobenzenesulfonate Calix[4]arene and CTAB

“…The literature describes an approach based on the combination of several components of a diverse structure due to various noncovalent interactions, e.g. hydrogen bonds, [2] metal-ligand coordination, [3] electrostatic, [4][5][6] pi-stacking, [7] and "hostguest" interactions [8] with the formation of superamphiphiles, which allowed creating a large number of systems possessing the properties of nanocontainers [9] and molecular devices. [10] Due to the dynamic nature of the non-covalent interactions of the superamphiphiles, it becomes possible to easily control their self-assembly and the properties of the emerging structures under the influence of various external factors.…”