Quantum Interference Effect in Saturated Systems: Effect of Anchoring Group Position on Conductance of Bipiperidines and their in-situ Derived Dithiocarbamates.

Abstract

This study investigates quantum interference in σ-only molecular systems, focusing on the impact of anchoring group nature and its position. Using a combined approach of mechanically controlled break junction experiments and quantum transport calculations, we demonstrate that meta-connected σ-conducting bipiperidine-based molecular junctions exhibit higher conductance than para-connected ones. This trend is opposite to that of the trend typically observed in π-molecular systems, indicating the existence of distinctly different quantum interference phenomenon in σ-only molecular systems. Further, we show that anchoring group modifications achieved through in-situ dithiocarbamylation significantly alters the conductance and decay factors. We also elucidate the mechanism behind multiple conductance features observed in aliphatic bipiperidines with cyclic secondary amine and dithiocarbamate anchoring groups. This work demonstrates σ-quantum interference in bipiperidine-based molecular systems and highlights how changes in junction configuration, nature of the anchoring group and its position can be used to control conductance in σ-only molecular systems.