We demonstrate electrochemical deposition of a specially designed and synthesized sigma-pi-sigma molecular architecture, that is, N-(2-(4-diazoniophenyl)ethyl)-N'-hexylnaphthalene-1,8: 4,5-tetracarboxydiimide tetrafluoroborate (DHTT), on H-terminated Si substrates. Electrografting of DHTT on Si at 5 and 27 degrees C leads to the formation of monolayer and multilayers, respectively. DHTT monolayer exhibits a pronounced negative differential resistance (NDR) in the current-voltage characteristics with peak-to-valley current ratio of similar to 10. Theoretical simulations studies show that the observed NDR effect is intrinsic to the DHTT molecules. NDR effect has been explained using the ab initio molecular-orbital theoretical calculations. (C) 2010 Elsevier B. V. All rights reserved.