Interactions between gemini surfactants, 12-s-12, and beta-cyclodextrin as investigated by NMR diffusometry and electric conductometry

Markus Nilsson, Celia Cabaleiro-Lago, Artur J. M. Valente, Olle Soderman

Forskningsoutput: TidskriftsbidragArtikelPeer review

51 Citeringar (Scopus)

Sammanfattning

The interaction between beta-cyclodextrin (CD) and gemini surfactant of the type alkyl-alpha,omega-bis(dodecyldimethyl-ammonium bromide) with different spacer lengths of 2, 8, and 10 carbons has been investigated by means of electric conductivity (EC) and proton self-diffusion NMR at 298 K. The formation of a 2: 1 (CD: gemini) complex in a two-step mechanism is observed with the first association constant (K-11) higher than the second one (K-21), but both relatively small in comparison with single C-12-tailed surfactant. The value of the association constants increased with spacer length both for the first and second associated CD, which indicates that the available space on the gemini molecule is important. The magnitudes of the association constant both for the first and second complexation are discussed. The first association constant is small ( when compared with the homologous single-chain surfactant) due to hydrophobic interaction between the hydrocarbon tails within the gemini molecule, while the second association constant shows no cooperativity and its magnitude is discussed in terms of steric constrains.

OriginalspråkEngelska
Sidor (från-till)8663-8669
Antal sidor6
TidskriftLangmuir
Volym22
Utgåva21
DOI
StatusPublicerad - 2006
Externt publiceradJa

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