Ruthenium–amine complexation for constructing self-assembled molecular films

A redox active self-assembled monolayer consisting of ethylenediamine moieties coordinated to RuIII ions was prepared through a vapor phase silane coupling of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPS) molecules onto a SiO2/Si substrate, followed by complexation of RuIII ions in an aqueous RuCl3 solution. A similar SAM with 3-aminopropyltriethoxysilane did not provide surface RuIII-complex, indicating that chelation ability plays a key role in immobilizing RuIII ions at the surface. The RuIII chelated AEAPS-SAM gave a couple of RuIII/RuIV redox peaks at +1.0 and −0.1 V vs. Ag/AgCl (3 mol dm−3 NaCl).