Author(s):
Nilsson, Markus 
; Cabaleiro-Lago, Celia ; Valente, Artur J. M. ; Söderman, Olle
Date: 2006
Persistent ID: http://hdl.handle.net/10316/10628
Origin: Estudo Geral - Universidade de Coimbra
Document details
Interactions between Gemini Surfactants, 12-s-12, and β-cyclodextrin As Investi...
Description
The interaction between β-cyclodextrin (CD) and gemini surfactant of the type alkyl-α,ω-bis(dodecyldimethylammonium 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 (K11) higher than the second one (K21), but both relatively small in comparison with single C12-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. http://dx.doi.org/10.1021/la061220e
The interaction between β-cyclodextrin (CD) and gemini surfactant of the type alkyl-α,ω-bis(dodecyldimethylammonium 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 (K11) higher than the second one (K21), but both relatively small in comparison with single C12-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. http://dx.doi.org/10.1021/la061220e
Document Type
Article
Language English
Language English
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