| A hierarchically structured material consisting of a 300 nm thick mesoporous silica film, prepared by a vapor-phase infiltration method that is microscopically patterned by a reactive wet stamping technique, is demonstrated. The two-dimensional hexagonal mesostructure consists of tubular pores of approx 2.4 nm in diameter that are aligned parallel to the film-pulling direction. The micropatterns, 1.5 pm wide strips oriented perpendicular to the direction of the nanopores and separated from each other by 1.5 microm gaps, were etched in such a manner so as to enable multiple regions of accessibility to the nanopores that would otherwise not be easy to access. Both the nanopore accessibility and orientation were confirmed by infiltration of a fluorescent polymer into the nanopores, resulting in polarization of the emission. After the etching process, mechanically interlocked molecules that act as gatekeepers were attached to the nanopore openings. Trapping and on-command release of luminescent probe molecules were demonstrated in these micropatterned mesoporous silica films. Two kinds of nanosystems based on azobenzene molecules attached inside the pores of the mesoporous silica are investigated. One system is operated by switching azobenzene molecules from trans conformation to cis and back. A change in polarity of the material was expected but was not observed. The other nanosystem is operated by forcing the azobenzene molecules to continuously switch between the two conformations. This agitation of azobenzene molecules is shown to facilitate the motion of other molecules through the pore. |
