Advances in host-guest chemistry of inorganic mesostructures ate creat
ing a new dimension in materials chemistry aimed at the synthesis of f
unctional mesoscopic systems. Mesostructured materials can now be made
with insulating, semiconducting and metallic properties. Guests, whic
h have recently been encapsulated within the channels of hexagonal mes
oporous silica hosts, MCM-41, include organic and inorganic polymers,
luminescent silicon clusters, buckminster-fullerenes, long-chain alkyl
thiolates, immobilized enzymes and a variety of inorganic, organometal
lic and organic compounds.