of the system (Figure , f), which is a measure of the total resistance of the material to flow, decreased with the increase in angular frequency. This behavior follows the Maxwell model and agrees with previous rheology studies for NaDC gels. The addition of the guest molecule pyrene, which is known to bind to the hydrophobic sites of the primary aggregates of bile salts, was used to probe if the presence of OTPh affects the properties of the primary aggregate binding site in NaDC aggregates. The fluorescence spectrum and singlet excited state lifetime of pyrene are sensitive to the local environment around pyrene. In addition, the long lifetime of the pyrene singlet excited state is suitable for fluorescence quenching studies, since the shortening of this lifetime occurs at low quencher concentrations. The inclusion of pyrene into protected supramolecular systems leads to a decrease of the quenching rate constant of excited pyrene and provides information on the mobility of the quencher to the site containing pyrene. Pyrene can also form excimers when an excited pyrene and a ground state pyrene are located in close proximity within a microheterogeneous system. These photophysical properties were compared for the fluorescence of pyrene in NaDC and OTPh/NaDC gels. The quenching of excited pyrene by nitromethane, as a neutral quencher, and iodide anion, as a negatively charged quencher, were studied to provide information on possible changes in the structure of the supramolecular binding site for pyrene when OTPh was added to the NaDC gel.