Highly stable radical anions generated by reduction of aromatic diimides in zirconium phosphonate self-assembled films

ORGN 610

Rodrigo O. Marcon, marcon@umc.br and Sergio Brochsztain, brochsztain@umc.br. CIIB, Universidade de Mogi das Cruzes, Av. Dr Cāndido Xavier de Almeida Souza 200, Mogi das Cruzes SP, 08780-911, Brazil
Self-assembled thin films of N,N'-bis-(2-phosphonoethyl)-1,4,5,8-naphthalenediimide (PNDI), N,N'-bis-(2-phosphonoethyl)-3,4,9,10-perylenediimide (PPDI) and N,N'-bis-(2-phosphonoethyl)-1,2,4,5-benzenetetracarboxymide (PPMI) containing up to 50 layers of the aromatic diimides were grown on quartz slides using the zirconium phosphonate (ZP) technique. When the films were immersed in aqueous solutions of the reducing agent sodium dithionite, in situ reduction of the aromatic diimides was observed, generating radical anions and dianions. The radical anions formed within the films were rather stable, persisting for several minutes in the presence of atmospheric oxygen. Atomic force microscopy (AFM) images showed that the film surfaces were rather smooth and pin-hole free. These evidences suggest that the ZP films of three diimides are compact, stable, and well-organized. The capacity to stabilize diimide radicals that absorb light in virtually all of the visible range makes ZP films quite suitable for a variety of applications, such as solar energy collectors, chromic sensors, and conducting films.