changes in the hemimicellar environment.To summarize, this work reports the excited-state Raman spectrum of Ru(bpy)32+ in the adsorbed layers of a surfactant on a solid at a solid-liquid interface under in situ equilibrium conditions. This opens the general possibility of observing the adsorption phenomenon by yet another sensitive technique to provide basic information on adsorbed layers at solid-liquid interfaces.Acknowledgment. P.S. and J.T.K. thank the NSF and DOE for financial support. N.J.T. and J.K.B. thank the NSF, AFOSR, and NIH for financial support.

PALEPU and VINCENT C . REINSBOROUGH. Can. J. Chem. 66, 325 (1988). Conductance measurements were used to identify and to obtain association constants for the complexes formed between cyclodextrins (CD) with emphasis on P-cyclodextrin (PCD), and surfactants such as sodium dodecylsulfate (SDS) and tetradecyltrimethyl ammonium bromide. With both anionic and cationic surfactants, a C D forms predominantly a 2:l CD/surfactant complex while with both PCD and y C D the main species is I: 1. y C D binds much less strongly with surfactants than both a C D and PCD. Cyclodextrins destroy micelles by complexing the surfactant monomers more strongly than they are bound in self-association.RAMAMURTHY PALEPU et VINCENT C. REINSBOROUGH. Can. J. Chem. 66, 325 (1988) On a utilisk des mesures de conductance pour identifier et pour obtenir les constantes d'association des complexes qui se forment entre des cyclodextrines (CD) et des agents de surface, principalement entre la P-CD et le dodCcylsulfate de sodium (DSS), tant au-dessous qu'au-dessus de la concentration micellaire critique. Tant avec les agents de surface anioniques que cationiques, la a-CD forme principalement un complexe 2:l de CD:agent de surface; par ailleurs, les P-et y-CD forment principalement des complexes 1:l. La -y-CD se lie moins fortement que les a-et P-CD avec les agents de surface. Par comparaison avec leurs propres auto-associations, les cyclodextrines complexent avec les agents de surface monomkres plus fortement que les monomkres se complexent avec lui-m&mes et elles dCtruisent ainsi les micelles.[Traduit par la revue]

Micellar aggregation numbers, n, have been obtained for sodium dodecyl sulfate (SDS) micelles in cyclodextrin (CD) solutions through static fluorescence quenching. For -cyclodextrin, /3-cyclodextrin, (hydroxylpropyl)-/3-cyclodextrin, maltosyl-/S-cyclodextrin, and /-cyclodextrin solutions, n was found to be essentially unchanged from the 59 ±5 value found in sodium dodecyl sulfate solutions without cyclodextrin present, even though the critical micelle concentrations as measured conductometrically had increased. The increases in critical micelle concentrations were consonant, with 1:1 CD/SDS complexation predominating over other complexes in all CD systems except for -CD solutions, where the 2:1 a-CD/SDS complex prevailed. The association constants of the fluorescence quencher, 9-methylanthracene, with SDS and with each of the pure cyclodextrins were determined to ensure preferred binding of the quencher with SDS micelles rather than with CD. The substituted cyclodextrins, dimethyl-/3-CD and trimethyl-/3-CD, were not amenable to the fluorescence quenching method. The implications of these findings to drug delivery are examined.

RAMAMURTHY PALEPU and VINCENT C. REINSBOROUGH. Can. J. Chem. 67,1550Chem. 67, (1989. Pre-micellar and micellar sodium perfluorooctanoate solutions (SPFO) were examined conductometrically with added a-cyclodextrin (a-CD), P-cyclodextrin (P-CD), and y-cyclodextrin (y-CD). The order of stability of the 1: 1 inclusion complex was P-CD > y-CD > a-CD determined largely by the goodness of fit of the fluorocarbon chain in the CD cavity. Sodium ion electrode studies revealed that some ~a + ion is associated with the P-CD/SPFO complex. As shown by fluorine-19 nmr, P-CD girds the SPFO molecule snugly amidship with the terminal CF3 group still in solution. On the other hand, SPFO manages only a weak penetration of the fluorocarbon chain into the smaller a-CD cavity.

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