Partially π-exposed 3D carbohelicene for mechanical tuning of conductance and thermopower in single-molecule junctions.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 42045201.
- Also identified by DOI 10.1038/s41467-026-71293-3 and PMC identifier 13121714.
- Licence recorded as CC BY-NC-ND.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
Helicenes, composed of ortho-fused benzene rings, possess a spring-like π-backbone, enabling electron delocalization through both bonds and space. Theoretical predictions suggest that mechanical stretching or compression of molecular junctions in higher-order diazahelicenes could increase conductance and thermopower. However, this theory has not been experimentally verified, likely due to the difficulty of forming robust higher-order helicene molecular junctions using existing heteroatom anchors and the high electrical resistance of metal-heteroatom bonds. Thus, constructing mechanically stable single-molecule junctions through multipoint metal-π interactions would be ideal. Here we verify this theory using a 3D carbohelicene with a shielded π-face bearing bulky tert-butyl groups and an exposed π-face lacking tert-butyl groups. This partially π-exposed 3D carbohelicene forms a robust monolayer on the Au(111) substrate at room temperature through multipoint metal-π interactions. Using the break-junction technique, we demonstrate a compression-induced increase in both peak conductance (10<sup>-3</sup>-10<sup>-2</sup> G<sub>0</sub>) and thermopower (-44 μV/K).