Metal ion independent conductance through bis-chelated metal complex molecular wires based on a bis(diphenylphosphino)aniline derivative

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 54; no. 19; pp. 7874 - 7881
• Main Authors: Gatto, Marco F, Sangtarash, Sara, Jago, David, Abram, R. Tom, Barrett, Eleanor, Sil, Amit, Koutsantonis, George A, Higgins, Simon J, Robertson, Craig M, Nichols, Richard J, Sadeghi, Hatef, Vezzoli, Andrea
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 13.05.2025
• Subjects: Aniline; Chelation; Coordination compounds; Copper; Devices; Gold; Ligands; Molecular orbitals; Phosphines; Quantum transport; Raman spectroscopy; Robustness; Transition metal compounds
• DOI: 10.1039/d5dt00292c
• ISSN: 1477-9226; 1477-9234

It is becoming increasingly evident that transition metal complexes impart desirable qualities in single-molecule electronics, and testing metallic centres in combination with appropriate ligands is salient to building the next generation of single-molecule devices. Metal-phosphine complexes have been the subject of very few studies, despite their extensive use in other areas of chemistry. In this contribution, we fabricated and studied robust single-molecule junctions using linear bis-chelated ligand-metal-ligand complexes of the type [M(PNP) 2 ]PF 6 (M = Cu( i ), Ag( i ) or Au( i ); PNP = bis(diphenylphosphino)aniline functionalised with methylthio contact groups). The robustness of the devices was evinced by surface-enhanced Raman spectroscopy (SERS) and scanning-tunnelling microscopy break junction (STM-BJ) methods, and the conductance of the devices was found to be independent of the central transition metal. Quantum transport calculations show consistent HOMO-LUMO gaps between the studied complexes in the transmission plots, supporting the experimental findings. This study shows that bis-chelation is a viable approach to the fabrication of stable and robust metal-phosphine devices. Bis(chelated) molecular wires allow fabrication of robust single-molecule junctions and show ion-independent charge transport properties.