Synthesis, characterization, and adsorption of novel fatty acid curcumin derivatives on cotton fibers pre-mordanted with iron(ii) sulfate heptahydrate.

This study investigates the effect of fatty acid modification on curcumin by evaluating (i) its photostability through photodegradation kinetics in DMSO under LED irradiation, and (ii) its ability to interact with pre-mordanted cotton fibers. Two novel monoacylated (MCFD) and diacylated (DCFD) curcumin fatty derivatives were synthesized via Steglich esterification using oleic acid as a model compound, achieving yields of 95 and 93.6%, respectively. Structural characterization was performed by FTIR, 1H NMR, and 13C NMR spectroscopy. The photodegradation behavior of curcumin and MCFD under the investigated conditions followed first-order kinetics; however, MCFD exhibited enhanced photostability, with a half-life of 542 min compared to 341 min for curcumin. Adsorption studies on cotton fibers pre-mordanted with FeSO4·7H2O revealed that dye uptake was influenced by both pH and temperature. Under neutral pH conditions, MCFD followed a pseudo-first-order kinetic model and was best described by the Langmuir isotherm, whereas turmeric extract followed a pseudo-second-order kinetic model and was better represented by the Freundlich isotherm. No measurable adsorption was observed for DCFD under the same conditions. Thermodynamic analysis indicated that the adsorption of both turmeric extract and MCFD was spontaneous and exothermic. Fatty acid modification altered the adsorption behavior of curcumin while preserving measurable interactions with pre-mordanted cotton fibers; independently, MCFD exhibited a longer photodegradation half-life than curcumin in DMSO. These results provide proof-of-concept evidence that fatty acid modification can enhance curcumin photostability while retaining its adsorption capacity onto pre-mordanted cotton fibers.