The presence of OTPh in the NaDC gel did not alter the quenching rate constant of singlet excited state pyrene by nitromethane. In solution and in the gel, the decrease in the fluorescence intensity of pyrene with increasing concentrations of nitromethane led to a linear dependence with the nitromethane concentration of the ratio of the emission intensities in the absence and presence of nitromethane (Figure and S15). The Stern-Volmer constants (eq 2) were the same for pyrene in NaDC and OTPh/NaDC solutions and gels (Table ), leading to a calculated quenching rate constant of ((3.4 ± 0.2) ×10 8 M -1 s -1 ) based on the lifetimes of excited pyrene measured in both gels (380-381 ns). The quenching of excited pyrene was also measured using time-resolved experiments for the emission decay of pyrene in OTPh/NaDC gels (Figure ) and in the OTPh/NaDC self-assembly in solution (Figure ). The scattering of light at the start of the decay was excluded from the fit and the decays were fit to a sum of two exponentials (eq 1) where the short lifetime corresponds to the emissions from OTPh and NaDC impurities, while the long-lived species corresponds to the emission from excited pyrene (Fig. , see the SI for details on the fitting procedure). In the presence of nitromethane, the lifetime of excited pyrene is shortened and only one lifetime for pyrene was observed. In addition, the I/III ratio for the pyrene emission in the presence of nitromethane did not change. These observations suggest that pyrene is located in one type of environment in the NaDC aggregates in solution and in the gel. The quenching rate constants of (3.0 ± 0.1) ×10 8 M -1 s -1 (Table ) was determined from the dependence of the observed decay rate constant with the nitromethane concentration (Figure , eq. 3). The ratio of 24 ± 7 between the quenching rate constants in water and NaDC aggregates in aqueous solution is higher than for sodium cholate (9.2 ± 0.8), which is consistent with the formation of more hydrophobic and compact primary aggregates for NaDC containing two hydroxyl groups compared to sodium cholate, which has three hydroxyl groups. These results show that the incorporation of OTPh into the NaDC gel did not alter the structure of the primary NaDC aggregates to which pyrene binds.