Confinement effect on ultrafast events of a salicylideneaniline derivative within mesoporous materials

Abstract

We report on femtosecond (fs) studies of HBA-4NP interacting with MCM41, Al-MCM41 and SBA15 materials, and discuss the dynamics of caged monomers and J-aggregates. For MCM41 and Al-MCM41 composites, and upon excitation at 380 nm (monomers region) the ultrafast dynamics (250 fs and 2.5 ps for HBA-4NP/MCM41, 350 fs and 3.5 ps for HBA-4NP/Al-MCM41) is slower than that observed in solution due to aggregates formation inside the material pores. While exciting at 410 nm, we got a slower behaviour. However, for HBA-4NP/SBA15 composites, with a low loading, where the caged monomers are the main guests, we recorded faster dynamics (200 fs and 2 ps) independently on the pumping wavelength. These results show how the properties of mesoporous materials, especially its pore size and Al-doping, affect the nature of the formed composites and their ultrafast photodynamics.