Encapsulation and characterisation of cationic benzo[a]phenoxazines in zeolite HY

Abstract

Different cationic fluorochromophores were sucessfully encapsulated by ship-in-the-bottle synthesis into supercages of zeolite HY. The cationic fluorochromophores are N-(5-amino-10-methyl-9H-benzo[a]phenoxazin-9-ylidene)ethanaminium (1a), N-(10-methyl-5-(propylamino)-9H-benzo[a]phenoxazin-9-ylidene)ethanaminium (1b), N-(5-(isopentylamino)-10-methyl-9H-benzo[a]phenoxazin-9-ylidene)ethanaminium (1c) and N¹-((5-(isopentylamino)-9H-benzo[a]phenoxazin-9-ylidene)propane-1,3-diaminium)monobromide (1d). The success of encapsulation was proved by TGA and N₂ adsorption analysis showing that zeolite Y is an excellent host for the stabilization of these fluorochromophores. Photophysical characterisation of encapsulated fluorochromophores by UV-Visible absorption and fluorescence confirmed their location inside the zeolite supercages. Thus, it was possible to develop a new approach to synthesize materials possessing benzo[a]phenoxazinium derivatives, which are potential optical sensors with high stability, without the need for solution synthesis of fluorochromophores.