Nanochannels for supramolecular organization of luminescent guests

Zeolites and mesoporous silica are versatile host materials for the supramolecular organization of a large variety of guests. The inclusion of luminescent molecules, complexes, or nanoclusters into ordered one-dimensional channel systems is particularly intriguing, as the resulting host-guest compounds may exhibit unique properties such as optical anisotropy, efficient energy transfer, and enhanced stability. Several levels of organization have been realized for zeolite L, extending from the interior of a given crystal to the channel entrances and the external surface as well as from the microscopic to the macroscopic scale. The diverse chemistry that is involved in the development of a highly organized and functional host-guest material is illustrated by the design of molecules which are able to selectively adsorb at the channel entrances and establish communication between included guests and external objects. The importance of phthalocyanines as chromophores for this particular concept is exemplified. Based on the extensive research on zeolite L, possibilities and recent developments in the field of mesoporous silica hosts are discussed, revealing that despite the obvious differences between microporous and mesoporous host-guest materials, many similarities and analogies exist.