Premium
Tuning the Thermal Relaxation of a Photochromic Dye in Functionalized Mesoporous Silica
Author(s) -
Mühlstein Lea A.,
Sauer Jürgen,
Bein Thomas
Publication year - 2009
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200801619
Subject(s) - photochromism , silanol , materials science , photochemistry , merocyanine , mesoporous silica , mesoporous material , steric effects , chemical engineering , irradiation , fading , kinetics , surface modification , nanotechnology , organic chemistry , chemistry , catalysis , telecommunications , physics , decoding methods , quantum mechanics , computer science , nuclear physics , engineering
In this study, it is shown that the kinetics of the back‐switching reaction of a photochromic spirooxazine dye encapsulated in mesoporous silica materials can be significantly influenced both by the space available to the dye molecules and by the functionalization of the silica wall. Steric hindrance of the ring‐closing process due to high dye content or small pore size leads to a slow fading speed of the irradiated dye species. Further, the density of surface silanol‐groups present at the silica walls has an effect on the switching behavior of the dye because of their ability to stabilize the zwitterionic merocyanine isomers, thereby slowing the fading process from the open to the closed form. This stabilization effect is further enhanced in the presence of acidic functional groups, while, in contrast, basic functional groups reduce the stabilization of the open‐from dye isomers, and thus a faster decay of the irradiated species is observed. Control over the fading speed of photochromic dyes is interesting for applications requiring a particularly fast or slow fading speed.