Effect of the Media on the Quantum Yield of Singlet Oxygen (O₂(¹Δ_g)) Production by 9H‐Fluoren‐9‐one: Microheterogeneous Systems

Abstract

The quantum yield (F D ) of singlet oxygen (O 2 ( 1 D g ) production by 9H-fluoren-9-one (FLU) is very sensitive to the nature of the solvent (0.02 in a highly polar and protic solvent, such as MeOH, to 1.0 in apolar solvents). This high sensitivity has been used for probing the interaction of FLU with micellar media and microemulsions based on anionic (sodium dodecyl sulfate, SDS; bis-(2-ethylhexyl)sodium sulfosuccinate, AOT), cationic (cetyltrimethylammonium chloride, CTAC) and nonionic (Triton X-100, TX) surfactants. Values of F D of FLU vary in a wide range (0.05 ± 1.0) in both microheterogeneous media and neat solvent, and provide information on the microenvironment of FLU, i.e., on its localization within organized media. In ionic and nonionic micellar media, as well as in four-component microemulsions, FLU is, to various extents, exposed to solvation by the polar and protic components of the microheterogeneous systems (water and/or butan-1-ol) in the micellar interfacial region (F D 0.05 ± 0.30). In contrast, in AOT reverse micelles (consisting of AOT as surfactant, cyclohexane as hydrophobic component, and water), FLU is located in the hydrophobic continuous pseudophase, and is totally separated from the micellar water pools (F D % 1.0).

Peroxyl radical reactions with carotenoids in microemulsions: Influence of microemulsion composition and the nature of peroxyl radical precursor

“…The carotenoids used in this study (77DH and ZETA) are selected because their radical spectra are wellresolved. Also, the different compositions of microemulsions used in this study and the pseudoternary phase diagram for the four components (SDS, 1-butanol, water and cyclohexane) have been reported by Martinez et al [21]. (single-column fitting image)…”

“…[1][2][3] depending on the type of the reacting free radical and the carotenoid [1][2][3]5,16,17]. Time-resolved peroxyl radical studies with carotenoids in micelles and microemulsions are very limited [18,19] although they can be used as simple models for cellular membranes [20][21][22]. Microemulsions are composed of water, oil (usually a hydrocarbon solvent such as cyclohexane), a cofactor (e.g.…”

“…Microemulsions can be classified according to the water to oil ratio into (1) water-in-oil (W/O) (2) oil-in-water (O/W). However, at intermediate ratios of water to oil, bicontinuous structures are formed where water and oil channels are separated by a monolayer of surfactant molecules [21]. Earlier studies have shown the schematic representations for W/O, O/W and bicontinuous microemulsions [21,23].…”

“…However, at intermediate ratios of water to oil, bicontinuous structures are formed where water and oil channels are separated by a monolayer of surfactant molecules [21]. Earlier studies have shown the schematic representations for W/O, O/W and bicontinuous microemulsions [21,23]. Unlike micelles, microemulsions have the advantage of the ability to dissolve large amounts of hydrophobic substances and to accommodate long molecules due to the presence of the oil and cofactor [24].…”

Photosensitizer‐Mesoporous Silica Nanoparticles Combination for Enhanced Photodynamic Therapy†

“…Particularly, Rose Bengal (RB) (Fig. 1), is extensively used as a singlet oxygen reference (79,(97)(98)(99)(100)(101)(102)(103)(104). According to its absorption range (no absorbance above 600 nm), RB is not considered a suitable PS for PDT.…”