Probing the chemical reactivity of interfaces: Investigation on the interaction of dehydroindigo with Laponite by UV-vis, Raman and infrared spectroscopy

A significant bathochromic shift (65 nm) of the DHI π®Ï€* transition band in the visible region and changes in the relative intensities and position of the Raman bands at 1530, 1378 and 1167 cm−1 assigned to ν(NCCN), δ(CN) and ν(CN) respectively, indicate that the interaction is stronger than expected for the van der Waals and polarization forces involved in the external surfaces interactions with the siloxane groups. It was also observed that DHI presents an enhanced photochemical stability when interacting with Laponite. These results indicate that hydrogen bonding between a DHI nitrogen atom and the −SiOH or MOH groups is mainly responsible for the behavior present in the DHI + Lap system.