In this work a novel method for synthesis of 1,8-dihydroxynaphthalene melanin was presented, as well as the physicochemical properties, molecular structure, and characteristics of the pigment. The proposed synthesis protocol is simple and cost-effective with no enzymes or catalysts needed. The final product is not adsorbed on any surface, since the pigment is the result of autooxidation of 1,8-dihydroxynaphthalene.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
February 2025
Molecular dynamics and transport coefficients change significantly around the so-called Arrhenius crossover in glass-forming systems. In this article, we revisit the dynamic processes occurring in a glass-forming macrocyclic crown thiaether above its glass transition, revealing two crossover temperatures: at 309 and at 333 K. We identify the second one as the Arrhenius crossover that is closely related to the normal-to-supercooled liquid transition in this compound.
View Article and Find Full Text PDFIn this study, we employed dielectric spectroscopy to investigate the effect of temperature and pressure on the ion dynamics of phosphonium ionic liquids (ILs) differing by the length of an alkyl chain, [P][TFSI] ( = 2, 6, 8, 12). We found that both temperature and pressure dependence of dc-conductivity (σ) determined for all examined ILs herein exhibit unique characteristics, unusual for aprotic ILs. Two regions differing by ion self-organization have been identified from the derivative analysis of σ() data.
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