Probing the Indigo Molecule in Maya Blue Simulants with Resonance Raman Spectroscopy

摘要: Maya blue (MB) simulants were prepared from mixtures of indigo and palygorskite (ind–paly) investigated by resonance Raman UV–vis absorption spectroscopies together with thermogravimetric analysis, aiming to enlarge the understanding dye–clay interaction, relationship between color chemical stability, alleged formation dehydroindigo (DHI); for comparative purposes, other using sepiolite, laponite, montmorillonite. The results obtained here suggest that greenish hue develops when ind–paly is heated seems be linked a decrease in molecular symmetry, which causes an increase oscillator strength band at 500 nm (forbidden under C2h symmetry) bathochromic shift narrowing intense electronic transition 657 (indigo). DHI characteristic features are not observed spectrum (457.9 nm) system, contrary what happens L...