Sensitized Phosphorescence with Anchored Naphthoate Energy Donors in Reverse Micelles

A series of cetyltrimethylammonium (CTA+) surfactants with naphthoate counterions have been used as donors of triplet-state energy for the acceptor blacetyl in reverse micelles of Aerosol OT (AOT). Microviscosities obtained by using fluorescence polarization measurements have been employed to describe the relative binding of different naphthoate counterions to the interfacial region of the micelle. Since the naphthoate moieties are associated with the CTA+ surfactant, they are anchored to the head groups in reverse micelles of AOT where biacetyl is solubillzed. Therefore, cetyttri-methylammonium naphthoate acts as a more efficient energy donor than the corresponding sodium salt that is not bound as effectively to the micelle interface. Counterion binding and several other parameters that affect the intensity of sensitized phosphorescence have been examined. © 1990, American Chemical Society. All rights reserved

Characterization of naphthoate surfactants in normal and reverse micellar systems via luminescence spectroscopy

Four surfactants with naphthoate counterions have been prepared from cetyltrimethylammonium bromide (CTAB). The normal micelles of these surfactants form with relative case compared to CTAB; however, the surfactants do not form reverse micelles in common organic solvents. In order to examine the naphthoate counterion behavior in reverse micelles, the surfactants were dissolved in reverse micelles of Aerosol OT (AOT). The microenvironments of the counterions in normal and reverse AOT micelles have been characterized by using counterion luminescence measurements, fluorescence quenching, and fluorescence probe studies. This characterization study represents a stage in the development of analytical methods based on energy transfer between the aromatic counterions and analytes in controlled proximity. Preliminary data showing examples of energy transfer between the naphthoate moiety and biacetyl in normal and reverse micelles are provided. © 1990

Determination of formation constants for .beta.-cyclodextrin complexes of anthracene and pyrene using reversed-phase liquid chromatography

The stoichlometry and apparent formation constants of anthracene and pyrene β-cyclodextrln (β-CD) complexes were determined by use of liquid chromatography. These values were measured in mobile-phase mixtures of methanol-water and in the same mixtures modified with 1 % v/v tort-butyl alcohol or cyclopentanol. The results show that anthracene forms a 1:1 complex with β-CD, and the apparent formation constant (K1) values in mobile-phase mixtures of 55 % v/v, 60% v/v, and 65% v/v methanol-water are 373, 242, and 136 M-1, respectively. Modification of the mobile-phase mixtures with 1% v/v tert-butyl alcohol or cyclopentanol produced a slight decrease in the anthracene K1 values. Pyrene exhibited prohibitively long retention times in the 55% v/v methanol-45 % v/v water mixture and also showed little interaction with β-CD in 60% v/v and 65% v/v methanol-water mixtures. However, a remarkable change in capacity factor was observed for pyrene in the presence of 1 % v/v tert-butyl alcohol or cyclopentanol. A stoichiometric ratio of 2:1 and apparent formation constant values of 1.88 X 107and 2.96 X 108 M-2 were determined for the β-CD:pyrene in 54% v/v methanol-45 % v/v mobile phase mixtures containing 1 % v/v cyclopentanol and 1 % v/v tert-butyl alcohol, respectively. The implication of β-CD:pyrene:alcohol ternary complex formation and analytical chemistry applications of the concomitant effects are discussed. © 1992, American Chemical Society. All rights reserved