A H-1-NMR STUDY OF CYCLODEXTRIN - HYDROCARBON SURFACTANT INCLUSION COMPLEXES IN AQUEOUS-SOLUTIONS

A H-1 NMR chemical shift (delta) study of a homologous series of hydro carbon (hc) (CxH2x+1CO2Na, x = 5, 7, 9, 11, 13) surfactants (S) has be en carried out in water and in binary solvent (D2O + cyclodextrin (CD) ) systems at 22 degrees C. Complementary H-1 NMR chemical shift (delta ) data of the cyclodextrins in binary (D2O + S) systems containing hc surfactants have also been obtained. Complex induced shift (CIS) value s for selected host or guest protons were found to increase as the alk yl chain (C-x) length of the surfactant increased. The CIS values are found to depend on the following factors: (i) the magnitude of the bin ding constant (K-i, i = 1:1, 2:1), (ii) the chain length of the surfac tant, (iii) the mole ratio of the host to guest species, (iv) the host -guest stoichiometry, and (v) the host-guest inclusion geometry. The C IS values of the CD-S systems have been analyzed using equilibrium mod els in which 1:1 complexes, 1:1 plus 2:1 complexes, and uncomplexed sp ecies are present. Differences in the binding affinity, stoichiometry, and inclusion geometry of the complexes formed between a given hc sur factant and the various cyclodextrins were observed.