Controlled alignment of molecular diodes via ionic assembly of cationic donor-(pi-bridge)-acceptor molecules on anionic surfaces.

Alignment of cationic donor-(pi-bridge)-acceptor molecules via metathesis with a self-assembled monolayer formed from sodium 3-mercapto-1-propanesulfonate results in ultra-thin rectifying Au-S-(CH2)3SO3-/A+-pi-D structures which exhibit optimum current ratios of 450 at +/-1 V for N-methyl-5-(4-dibutylaminobenzylidene)-5,6,7,8-tetrahydroisoquinolinium.