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The effect of hydrophobic‐lipophilic interactions on chemical reactivity. 11. The dependence of the wrapping‐up capability of sodium carboxymethylamylose on its degree of substitution
Author(s) -
Jiang XiKui,
Li XingYa,
Huang BangZhou
Publication year - 1988
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.610010303
Subject(s) - chemistry , hydrogen bond , solvent , hydrophobic effect , iodine , titration , bromide , intramolecular force , dissociation constant , sodium , inorganic chemistry , crystallography , molecule , organic chemistry , biochemistry , receptor
The dependency of the wrapping‐up capability of sodium carboxymethylamylose (NaCMA) on its degree of substitution (D. S. = 0·00, 0·12, 0·18, 0·24, 0·29, 0·35 and 0·41) have been studied, using two guest species, iodine and cetyl‐trimethylammonium bromide (CTAB). The λ max values of NaCMA‐iodine helical inclusion complexes decrease with increasing D. S. values and the amounts of encapsulated iodine by NaCMA as measured by amperometric titrations also decrease with increasing D. S. values. With CTAB as the substrate, the largest number of binding sites, n , and the dissociation constants K d have been determined by the method of surface tension versus the CTAB concentration plots. The results show that n decreases while K d increases with increasing D. S. values. All these observations point to the fact that the wrapping‐up capability of NaCMA decreases with increasing degrees of substitution. The results are discussed in terms of host‐guest and host‐solvent hydrophobic‐lipophilic interactions as well as intramolecular hydrogen‐bonding.