Confinement effect of nanocages and nanotubes of mesoporous materials on the keto forms photodynamics of Sudan I

We report on steady-state and picosecond-time resolved emission spectra of Sudan I interacting with MX (M = Na+, Li+), NaY and MCM-41 materials in solid state. The results indicate that the interaction of the dye with these materials largely increases the emission decay times of tautomers and conformers, respectively produced by an ultrafast excited-state intramolecular-proton-transfer and trans–cis isomerization. The observation is explained in terms of space and electronic confinements within the cavities. We show that the interactions of the dye with the frameworks are more diverse while the charge-balancing cations affect the excited-state dynamics to a similar extent.