Phenoxazine dyes in zeolite L, synthesis and properties

The preparation and characterisation of brightly luminescent dye-zeolite L host-guest microcrystals and of nitro, amino, N-acetyl, and N-alkyl phenoxazine dyes is reported. The synthesis of 3-ethylamino-7-ethyliminophenoxazinium nitrate (9) is based on five steps including simple and highly efficient silver-catalysed oxidation at room temperature, which can also be used to synthesise oxonine (6). 6 and 9 are inserted in about 1.5 mum long zeolite L crystals by means of ion exchange. The former from an aqueous suspension and the latter from 1-butanol by applying a selective ionophore. The orientation of the electronic transition dipole moment of 9 inside of the linear channels of zeolite L, as observed by fluorescence microscopy, is compared with that of four other selected dye-zeolite L microcrystals. (C) 2003 Elsevier Inc. All rights reserved.