Vibrational Spectroscopic Studies of the Attachment Chemistry for Zirconium Phosphonate Multilayers at Gold and Germanium Surfaces

The attachment chemistry required for the sequential self-assembly of zirconium phosphonate (ZP) monolayers on gold and germanium surfaces is examined with a combination of attenuated total reflection (ATR-FTIR) and polarization modulation (PM-FTIR) Fourier transform infrared spectroscopies. On the germanium substrates, the conversion of an attached o-aminosilane monolayer to phosphate amide species creates a primer for the sequential deposition of multilayer films of zirconium 1,lO-decanediylbis(phosphonate) (Zr/DBP). On vapor-depoeited gold f i , a packed monolayer of 11-mercapto-1-undecanol (MUD) serves as the basis for a primer monolayer. PM-FTIR measurements show that phosphorylation of the terminal hydroxy groups results in a surface with a mixture of phosphate monoand diesters, which bind W+ to commence the self-assembly of the Zr/DBP multilayers. On both substrates, the alkyl chain regions of the ZP film are observed to be conformationally disordered due to the control of the lateral spacing in the f i by the inorganic (phoephonate-Zr-phoephonate) regions. Furthermore, the packing density, order, and chemical structure of the primer layer are found to influence the resulting ZP multilayer structure.