Systems consisting of layered structures and photoactive molecules have been studied extensively. The structures of resulting complexes may be controlled by UV–Vis radiation, which subsequently affects their materials properties. This study describes a synthesis route for obtaining a photoresponsive kaolinite intercalation compound. The material was prepared by co-intercalating azobenzene and benzylalkylammonium chlorides into a methoxy form of kaolinite. The resultant materials possessed large basal spacing values in the range of 45–55 Å. The UV–Vis and Fourier-transform infrared spectroscopy analyses confirmed the reversible photoisomerization of azobenzene upon exposure to UV and Vis radiation. This phenomenon was significantly influenced by the type and amount of co-intercalated molecules. Upon multiple trans–cis conversions, the azobenzene partially evaporated. For the first time, a kaolinite-based material was prepared that exhibited photochromic behaviour upon UV and Vis irradiation.

Intercalation of an ammonium amphiphile having an azobenzene chromophore, 4-dodecyloxy-4 ‘-(trimethylammoniopentyloxy)azobenzene and 4-(ω-trimethylammoniodecyloxy) -p’- (octyloxy)azobenzene bromide, into the layered silicate magadiite (ideal formula Na2Si14O29·nH2O) was carried out by a conventional ion exchange reaction in an aqueous medium. An intercalation compound with the ideal formula {(C12AzoC5N+)1.4H0.6·Si14O29·nH2O} was obtained. Based on the change in the basal spacing (to 4.21 nm) after the reaction and the visible absorption spectrum of the product, the intercalated azo dyes appear to form a J-aggregate in the interlayer space of magadiite. Under UV and visible light irradiation, the intercalated azo chromophore exhibited reversible transcis isomerization in the interlayer space of magadiite. This is the first successful report of photochemical reactions of guest species in the interlayer space of magadiite.

The following article is an edited transcript based on the MRS Medalist presentation given by C. Jeffrey Brinker (Sandia National Laboratories and the University of New Mexico) on December 3, 2003, at the Materials Research Society Fall Meeting in Boston. Brinker received the Medal for “his pioneering application of principles of sol-gel chemistry to the self-assembly of functional nanoscale materials.” Nature combines hard and soft materials, often in hierarchical architectures, to obtain synergistic, optimized properties with proven, complex functionalities. Emulating natural designs in robust engineering materials using efficient processing approaches represents a fundamental challenge to materials chemists. This presentation reviews progress on understanding so-called evaporation-induced silica/surfactant self-assembly (EISA) as a simple, general means of preparing porous thin-film nanostructures. Such porous materials are of interest for membranes, low-dielectric-constant (low-k) insulators, and even ‘“nano-valves” that open and close in response to an external stimulus. EISA can also be used to simultaneously organize hydrophilic and hydrophobic precursors into hybrid nanocomposites that are optically or chemically polymerizable, patternable, or adjustable.