Ultrafast Dynamics of the Medicinal Pigment Curcumin inside the Imidazolium Surface Active Ionic Liquid Containing Giant Vesicles and White Light Generation via Triple-FRET Technique

The naturally occurring yellow polyphenolic medicinalpigment curcuminshows ultrafast dynamics in the excited states. These ultrafast dynamicsare strongly influenced by the rigidity of the environments of thesystems. The present investigation unveils the ultrafast excited-stateintramolecular hydrogen atom transfer (ESIHT) (which is involved inthe antioxidant mechanism) and the solvation dynamics of curcumininside the imidazolium surface active ionic liquid (SAIL), 1-hexadecyl-3-methylimidazoliumchloride ([C(16)mim]Cl) micelle, and giant vesicles afterintroducing sorbitan monoesters (Span 20 and Span 80) in the aqueousmedium. Interestingly, the short hydrocarbon chain containing Span20 forms smaller, less rigid vesicles, and the long hydrocarbon chaincontaining Span 80 forms larger, more rigid giant vesicles after beingassembled with [C(16)mim]Cl. The ESIHT and the solvationdynamics are slower in Span 80, containing rigid vesicles, than thatin Span 20, comprising less rigid vesicles. Finally, we have establisheda three-component fluorescence resonance energy transfer (Triple-FRET)system to generate white light (WL) in the micelle and giant vesicles.Here the hydrophobic dye 1,6-diphenyl-1,3,5-hexatriene (DPH) actsas the donor, and the hydrophilic anticancer drug doxorubicin hydrochloride(DOX) serves as the acceptor along with the intermediate donor, curcumin.At a specific combination of the concentrations of these dyes in aparticular self-assembled system, WL is generated due to the triple-FRETphenomena.

Automated summary

This study reveals the ultrafast dynamics of the naturally occurring yellow polyphenolic medicinal pigment curcumin in the excited states, which is strongly influenced by the rigidity of the environments. The investigation also uncovers the ultrafast excited-state intramolecular hydrogen atom transfer (ESIHT) and solvation dynamics of curcumin in different self-assembled systems. Furthermore, a three-component fluorescence resonance energy transfer (Triple-FRET) system has been established to generate white light in micelles and giant vesicles.