Fluorescence emission of pyrene in surfactant solutions

Abstract

The systematic description of the complex photophysical behaviour of pyrene in surfactant solutions in combination with a quantitative model for the surfactant concentrations reproduces with high accuracy the steady-state and the time resolved fluorescence intensity of pyrene in surfactant solutions near the cmc, both in the monomer and in the excimer emission bands. We present concise model equations that can be used for the analysis of the pyrene fluorescence intensity in order to estimate fundamental parameters of the pyrene-surfactant system, such as the binding equilibrium constant K of pyrene to a given surfactant micelle, the rate constant of excimer formation in micelles, and the equilibrium constant of pyrene-surfactant quenching. The values of the binding equilibrium constant K(TX100)=3300·10³ M⁻¹ and K(SDS)=190·10³ M⁻¹ for Triton X-100 (TX100) and SDS micelles, respectively, show that the partition of pyrene between bulk water and micelles cannot be ignored, even at relatively high surfactant concentrations above the cmc. We apply the model to the determination of the cmc from the pyrene fluorescence intensity, especially from the intensity ratio at two vibronic bands in the monomer emission or from the ratio of excimer to monomer emission intensity. We relate the finite width of the transition region below and above the cmc with the observed changes in the pyrene fluorescence in this region.

Free energy approach to micellization and aggregation: Equilibrium, metastability, and kinetics

“…(For alternative views, see Refs. [15,17].) For example, since many observations rely on fluorescence techniques, one should consider the effect of the fluorescent dye on the micellization [43].…”

“…This approach was criticized for its restriction to single-monomer kinetics, disregarding effects of micellar fusion and fission [15][16][17], and was argued to be limited to cases of high CMC and small aggregation number [16].…”

Synthesis, antibacterial activities and phospholipid membrane interactions of novel dialkyl 2,2’-disulfanediyldibenzoates

“…The onset of micellar formation when a surfactant is added to an aqueous solution of pyrene causes an abrupt decrease in the I1/I3 ratio, due to the solubilisation of pyrene molecule solubilized within the hydrophobic interior of micellar aggregates [25]. Figure 3 illustrates the fluorescence and CMC graph of compound 2.…”

Self-assembled Nanogels of Carborane-bearing Polysaccharides for Boron Neutron Capture Therapy

“…In contrast, the I 1 /I 3 ratio of the CAP decreased to around 1.1, which is consistent with the value normally obtained for pyrene following its incorporation into the hydrophobic core of a surfactant micelle. 20 The fluorescence quenching technique 21 was applied to determine the aggregation numbers of carborane in the hydrophobic nanodomains of the nanogels. The concentration dependence of the intensity of the pyrene emission at 384 nm in the presence of CAP nanogels (0.52.5 mg mL ¹1 ) was determined as a function of concentration of cetylpyridinium chloride (CPC), which was used as a fluorescence quencher.…”