Conductance in a bis-terpyridine based single molecular breadboard circuit

• Published in: Chemical science (Cambridge) Vol. 8; no. 2; pp. 1576 - 1591
• Main Authors: Seth, Charu, Kaliginedi, Veerabhadrarao, Suravarapu, Sankarrao, Reber, David, Hong, Wenjing, Wandlowski, Thomas, Lafolet, Frédéric, Broekmann, Peter, Royal, Guy, Venkatramani, Ravindra
• Format: Journal Article
• Language: English
• Published: England The Royal Society of Chemistry 2017
• Subjects: Chemical Sciences; Circuits; Conductance; Constituents; Electric charge; Electrodes; Estimates; Feature extraction; Terminals
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c6sc03204d

Controlling charge flow in single molecule circuits with multiple electrical contacts and conductance pathways is a much sought after goal in molecular electronics. In this joint experimental and theoretical study, we advance the possibility of creating single molecule breadboard circuits through an analysis of the conductance of a bis-terpyridine based molecule (
). The
molecule can adopt multiple conformations through relative rotations of 7 aromatic rings and can attach to electrodes in 61 possible single and multi-terminal configurations through 6 pyridyl groups. Despite this complexity, we show that it is possible to extract well defined conductance features for the
breadboard and assign them rigorously to the underlying constituent circuits. Mechanically controllable break-junction (MCBJ) experiments on the
molecular breadboard show an unprecedented 4 conductance states spanning a range 10
to 10
. Quantitative theoretical examination of the conductance of
reveals that combinations of 5 types of single terminal 2-5 ring subcircuits are accessed as a function of electrode separation to produce the distinct conductance steps observed in the MCBJ experiments. We estimate the absolute conductance for each single terminal subcircuit and its percentage contribution to the 4 experimentally observed conductance states. We also provide a detailed analysis of the role of quantum interference and thermal fluctuations in modulating conductance within the subcircuits of the
molecular breadboard. Finally, we discuss the possible development of molecular circuit theory and experimental advances necessary for mapping conductance through complex single molecular breadboard circuits in terms of their constituent subcircuits.