Elucidating the Photoluminescence Quenching in Ensulizole: an Artificial Water Soluble Sunscreen

Abstract

Employing natural or arti cial sunscreens is essential to protect the skin from ultraviolet radiations that cause premature aging and develop melanoma and other forms of skin cancer. The 2-Phenylbenzimidazole-5-sulfonic acid, commonly known as ensulizole is a water-soluble arti cial sunscreen that absorbs mostly UV-B (280 nm − 315 nm) radiations and protects the skin against the harmful effects of these radiations. Steady-state absorption indicates a strong absorption feature at 303 nm and a weak at 316 nm that have been identi ed as π → π* and n → π* transitions, respectively. The photoluminescence (PL) spectra indicate that the PL of ensulizole is less Stokes-shifted in polar solvents and more Stokes-shifted in non-polar solvents. The average PL lifetime of ensulizole is longer in non-polar solvents as compared to polar solvents and it exhibits the shortest PL lifetime in aqueous medium that signi es its e ciency in water. This suggests in non-polar solvents intersystem crossing is the dominant mode of relaxation of the excited ππ* state. Furthermore, an increase of pH of ensulizole solution decreases the PL intensity and the lifetime.Stern-Volmer equation is employed to evaluate bimolecular quenching rate constant k q that suggests the diffusional dynamic mode of PL quenching is operative.

Exploring the photoexcited electron transfer dynamics in artificial sunscreen PBSA-coupled biocompatible ZnO quantum dots

“…Further details of the measurements are given in our previously reported work. 35 Cyclic voltammetry (CV) curves are recorded using a CH1660B electrochemistry workstation.…”

FeVO4 nanowires for efficient photocatalytic CO2 reduction

“…5(f) and Table S1† showed that the average emission lifetime of FeVO 4 nanowires (32.78 ns) was much longer than FeVO 4 bulk (1.41 ns), which revealing that the recombination of photogenerated carriers was more restrained in FeVO 4 nanowires. 41…”

“…5(f) and Table S1 † showed that the average emission lifetime of FeVO 4 nanowires (32.78 ns) was much longer than FeVO 4 bulk (1.41 ns), which revealing that the recombination of photogenerated carriers was more restrained in FeVO 4 nanowires. 41 In the photocatalytic experiment, the separation and transfer of photogenerated charges restricted the reaction activity. One of the important factors is that the higher conductivity means that the photogenerated carriers will migrate to the surface of the catalyst more quickly to participate in the chemical reaction.…”

Cu-Enhanced Efficient Förster Resonance Energy Transfer in PBSA Sunscreen-Associated Ternary CuxCd1–xS Quantum Dots

“…The samples were excited with a pulsed LED laser source at 306 nm, and the PL was measured at room temperature as described in our previously reported work. 30 …”

“… 29 2-Phenylbenzimidazole-5-sulfonic acid (PBSA), also recognized as “ensulizole”, is a renowned UV-B-type artificial sunscreen filter. 30 Previously, this compound was analyzed extensively as an environmental pollutant in the treatment of wastewater. 31 − 34 …”