Characterization of self-assembled thin films of zirconium phosphonate/aromatic diimides

The synthesis of three novel phosphonate-substituted aromatic diimides is described: N,N′-bis(2-phosphonoethyl)pyromellitimide (PPMI), N,N′-bis(2-phosphonoethyl)-1,4,5,8-naphthalenediimide (PNDI) and N,N′-bis(2-phosphonoethyl)-3,4,9,10-perylenediimide (PPDI). The imides are water-soluble, allowing spectroscopical studies to be performed in water. PPMI and PNDI exist in the monomeric form in water, but PPDI formed dimers. Self-assembled thin films of the three compounds were grown on phosphonate-primed silicon and quartz substrates by the zirconium phosphonate method. Film growth was followed by ellipsometry (silicon) and ultraviolet/visible absorption spectroscopy (quartz). The films obtained were highly thermally and solvolitically stable for all the three imides, making them excellent candidates for applications in nanotechnological devices.