TY - JOUR

T1 - Chemistry of the Au-Thiol Interface through the Lens of Single-Molecule Flicker Noise Measurements

AU - Rashid, Umar

AU - Bro-Jørgensen, William

AU - Harilal, K. B.

AU - Sreelakshmi, P. A.

AU - Mondal, Reetu Rani

AU - Chittari Pisharam, Varun

AU - Parida, Keshaba N.

AU - Geetharani, K.

AU - Hamill, Joseph M.

AU - Kaliginedi, Veerabhadrarao

N1 - Funding Information: V.K. and U.R. acknowledge the funding support from the Indian Institute of Science, DST-INSPIRE (DST/INSPIRE/04/2018/002983), SERB-Core research grant (CRG/2020/002302). U.R., PA.S., and R.R.M. acknowledge the financial support from the Prime Minister Research Fellowship (PMRF), Government of India. K.N.P. acknowledges CSIR for Pool Scientist [SRA, 13(9206-A)/2021-POOL]. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Programme (Grant Agreement No. 865870). The authors highly acknowledge Prof. Gemma C. Solomon, Dr. Gustav Wiberg, Dr. Garima Jindal, Dr. Vignesh Palani, and Prof. Latha Venkataraman for their useful comments and suggestions. Publisher Copyright: © 2024 American Chemical Society

PY - 2024

Y1 - 2024

N2 - Chemistry of the Au-S interface at the nanoscale is one of the most complex systems to study, as the nature and strength of the Au-S bond change under different experimental conditions. In this study, using mechanically controlled break junction technique, we probed the conductance and analyzed Flicker noise for several aliphatic and aromatic thiol derivatives and thioethers. We demonstrate that Flicker noise can be used to unambiguously differentiate between stronger chemisorption (Au-SR) and weaker physisorption (Au-SRR′) type interactions. The Flicker noise measurements indicate that the gold rearrangement in chemisorbed Au-SR junctions resembles that of the Au rearrangement in pure Au-Au metal contact breaking, which is independent of the molecular backbone structure and the resulting conductance. In contrast, thioethers showed the formation of a weaker physisorbed Au-SRR′ type bond, and the Flicker noise measurement indicates the changes in the Au-anchoring group interface but not the Au-Au rearrangement like that in the Au-SR case. Additionally, by employing single-molecular conductance and Flicker noise analysis, we have probed the interfacial electric field-catalyzed ring-opening reaction of cyclic thioether under mild environmental conditions, which otherwise requires harsh chemical conditions for cleavage of the C-S bond. All of our conductance measurements are complemented by NEGF transport calculations. This study illustrates that the single-molecule conductance, together with the Flicker noise measurements can be used to tune and monitor chemical reactions at the single-molecule level.

AB - Chemistry of the Au-S interface at the nanoscale is one of the most complex systems to study, as the nature and strength of the Au-S bond change under different experimental conditions. In this study, using mechanically controlled break junction technique, we probed the conductance and analyzed Flicker noise for several aliphatic and aromatic thiol derivatives and thioethers. We demonstrate that Flicker noise can be used to unambiguously differentiate between stronger chemisorption (Au-SR) and weaker physisorption (Au-SRR′) type interactions. The Flicker noise measurements indicate that the gold rearrangement in chemisorbed Au-SR junctions resembles that of the Au rearrangement in pure Au-Au metal contact breaking, which is independent of the molecular backbone structure and the resulting conductance. In contrast, thioethers showed the formation of a weaker physisorbed Au-SRR′ type bond, and the Flicker noise measurement indicates the changes in the Au-anchoring group interface but not the Au-Au rearrangement like that in the Au-SR case. Additionally, by employing single-molecular conductance and Flicker noise analysis, we have probed the interfacial electric field-catalyzed ring-opening reaction of cyclic thioether under mild environmental conditions, which otherwise requires harsh chemical conditions for cleavage of the C-S bond. All of our conductance measurements are complemented by NEGF transport calculations. This study illustrates that the single-molecule conductance, together with the Flicker noise measurements can be used to tune and monitor chemical reactions at the single-molecule level.

U2 - 10.1021/jacs.3c14079

DO - 10.1021/jacs.3c14079

M3 - Journal article

C2 - 38381861

AN - SCOPUS:85186078508

VL - 146

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 13

ER -