Reactivity of Benzophones in the Different Binding Sites of Sodium Cholate Aggregates

Abstract

The reactivity of excited benzophenone (Bp) and 4,4‘-dimethylbenzophenone (DMBp) in the presence of sodium cholate (NACh) aggregates was studied by following the kinetics of the excited triplet states and the ketyl radicals of both ketones. At low NACh concentrations only primary aggregates are present in solution. The ketyl radicals were formed from the reaction of the triplet ketones bound to the primary sites. The decay of the ketyl radicals occurred primarily by the reaction of these radicals in water. Some long-lived triplets included in the primary aggregate were also observed. A different reactivity was observed at higher NACh concentrations where secondary aggregates are present. The binding process associated with the secondary binding sites is much faster than for the primary site. The hydrogen abstraction reaction in the secondary binding site is too slow to compete with the exit process, but self-quenching competes efficiently, leading to a shortening of the triplet lifetimes for both ketones. From the dynamic results it was concluded that only a small number of NACh molecules (8−13) are needed to define the primary and secondary binding sites.

Spectrometric study on the interaction of sodium cholate aggregates with quercetin

“…As a result, quercetin bound with quercetin micelles shows further higher intensities of absorption and fluorescence than quercetin with NaC monomers and dimers. Bohne et al previously suggested that hydrophobic compounds with hydrophilic moieties prefer to be incorporated into bile salt aggregates at concentrations when secondary aggregates are formed [9][10][11]. Compared to NaC primary micelles, bigger solubilized space of secondary micelles can increase the extended aromatic conjugation of the planar geometry of quercetin and lead to more enhanced absorption and fluorescence of quercetin.…”

“…The study on the interaction of bile salts with curcumin reported by Patra et al disclosed that the physicochemical properties of curcumin changed dramatically with the addition of bile salts [8]. Bohne et al revealed that the binding sites and binding dynamics of bioactive compounds with bile salt aggregates are different in the primary micelles and the secondary micelles, depending on the structures of the incorporated bioactive compounds [9][10][11]. Owing to the presence of two different types of binding sites, bile salt micelles were suggested to be suitable for carrying both hydrophobic and hydrophilic bioactive molecules [12].…”

Kinetics of fast reactions of triplet states and radicals under photolysis of 4,4′-dimethylbenzophenone in the presence of 4-halophenols in micellar solutions of sodium dodecyl sulfate in magnetic field

“…1, curve 4) of a longer lived intermediate product, ketyl radical DBH • , is ob served. 9, 20 The absorbance (i.e., observed amount of rela tively long lived radicals DBН • ) increases substantially when an external magnetic field is applied (cf. intensities of absorbance at 530 nm detected 4 µs after laser pulse in the absence and presence of the external magnetic field in kinetic curves 2 and 1, respectively (Fig.…”

Effect of Solvent Polarity and Viscosity on the Guest Binding Dynamics with Bile Salt Aggregates†

“…Bile salts form aggregates in aqueous solution because of their amphiphilic nature, where one face of the molecule is hydrophobic and the other face is relatively hydrophilic (1–8). At low concentrations of monomer, small aggregates called primary aggregates are formed, while at high concentrations, the primary aggregates agglomerate further forming larger structures called secondary aggregates (Scheme 1) (2,4,7–23). The key feature of this supramolecular host system is that it contains two binding sites with different properties (16,22,24–26).…”