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Abstract

This chapter discusses the optical applications of nanoporous materials. Porous materials are highly interesting and fascinating for scientists because of their unique porosity-related properties. Nanoporous materials are divided into three classes relative to the pore dimensions: microporous with pore diameters up to 2 nm, mesoporous with pore diameters from 2 to 50 nm, and macroporous with even bigger pores. New materials based on zeolites are treated as representatives of microporous materials and ordered mesoporous materials. Zeolites are synthesized mostly via a hydrothermal procedure. The various pathways for the incorporation of inorganic or organic guest species in the pore system of zeolites and ordered mesoporous materials include ion exchange—either in solution or in solid state—adsorption from the liquid or the gas phase, solid-state reaction, inclusion during the synthesis of the molecular sieve, covalent anchoring of guest species by grafting reactions, or intrazeolite synthesis within the zeolitic voids from small precursor species. A class of gas-sensitive materials based on zeolites consists of semiconductor nanoparticles incorporated in zeolites. The zeolite matrix is used to stabilize the nanoparticles and to prevent them from forming bigger agglomerates. Zeolites are especially useful because they additionally allow the accessibility of the clusters by small gas molecules. This leads to the development of materials that could be used as gas sensors. Considerable success has been achieved in synthesizing novel optically functional materials based on zeolite guest–host chemistry.