Controlling photoreactions with confinement: Photochemistry of benzoin alkyl ethers within water soluble p-sulfonato calix[n]arenes

This publication pertains to the exploration of supramolecular assemblies to control excited state chemistry. One of our long-range scientific goals is to develop, on the basis of well-established rules of molecular organic photochemistry and supramolecular chemistry, a model to predict the photobehavior of organic molecules in restricted spaces, in general. We present the results of our studies on the photochemistry of benzoin alkyl ethers included within calixarenes in water. While in isotropic solution benzoin alkyl ethers yield products of Norrish Type I reaction, as guest-host complex with calixarenes they preferentially yield products of Norrish Type II reaction. The current observation suggests that rules of physical organic chemistry and photochemistry developed based on solution chemistry cannot be simply extended to supramolecular assemblies. (C) 2008 Elsevier B.V. All rights reserved.