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Biphasic kinetics and flip‐flop behaviour of vesicles of fluorocarbon amphiphiles with a 1,3‐disubstituted glycerol structure
Author(s) -
Liang Kangning,
Hui Yongzheng
Publication year - 1992
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610051014
Subject(s) - chemistry , fluorocarbon , vesicle , amphiphile , kinetics , nucleophile , bilayer , molecule , reaction rate constant , hydrolysis , polymer chemistry , organic chemistry , membrane , copolymer , biochemistry , physics , quantum mechanics , catalysis , polymer
Fluorocarbon amphiphiles with a 1,3‐disubstituted thioglycerol structure form stable unilamellar vesicles. The fluorocarbon bilayer of an amphiphile which has an ammonium salt as head group is an ‘insulator’ for the permeation of hydroxide anions. In the presence or absence of a fluorocarbon nucleophile, hydrolysis of a probe amphiphile carrying a cleavable p ‐nitrophenyl ester group in the vesicle under alkaline conditions shows a pattern of biphasic kinetics, in which the fast and slow reaction can be attributed to the hydrolysis of probe molecules at outer and inner surfaces of vesicles, respectively. The fact that the slow rate constant always remains constant at 0.25 min −1 at 25°C, independent of the pH of the system and of concentration of the nucleophile, indicates that the slow process is an outward flip‐flop process of probe molecules within the fluorocarbon domain.