N-Silylamine Junctions for Molecular Wires to Gold: The Effect of Binding Atom Hybridization on the Electronic Transmission

In molecular conduction studies, amine groups are often used as linkers between molecules and gold surfaces. We demonstrate using density functional theory (DFT) that N-silyl substitution of 1,4-benzenediamine (BDA) produces a highly polarizable junction with a conductance and electrostatic profile that depends strongly on the local hybridization. In BDA itself, a forced change in hybridization from sp3 to sp2 is predicted to increase the conductivity by an order of magnitude. N-silyl substitution is shown to make this effect accessible while maintaining a 5-fold conductance ratio and sufficient binding strength to allow junctions to spontaneously assemble. Hence N-silylamines are predicted to form useful, externally controllable molecular junctions.