Unusual length dependence of the conductance in cumulene molecular wires

Journal article

Cumulenes are sometimes described as “metallic” because an infinitely long cumulene would have the band structure of a metal. Herein, we report the single‐molecule conductance of a series of cumulenes and cumulene analogues, where the number of consecutive C=C bonds in the core is n=1, 2, 3, and 5. The [n]cumulenes with n=3 and 5 have almost the same conductance, and they are both more conductive than the alkene (n=1). This is remarkable because molecular conductance normally falls exponentially with length. The conductance of the allene (n=2) is much lower, because of its twisted geometry. Computational simulations predict a similar trend to the experimental results and indicate that the low conductance of the allene is a general feature of [n]cumulenes where n is even. The lack of length dependence in the conductance of [3] and [5]cumulenes is attributed to the strong decrease in the HOMO–LUMO gap with increasing length.

Authors: Xu, W; Leary, E; Hou, S; Sangtarash, S; González, M

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: Angewandte Chemie International Edition
• Volume: 58
• Issue: 25
• Pages: 8378–8382
• Publication date: 2019-05-17
• Acceptance date: 2019-04-26
• DOI: 10.1002/anie.201901228
• EISSN: 1521-3773
• ISSN: 1433-7851
• Pmid: 31026371
• Language: English
• Keywords: cumulenes; molecular wires; conductance; single-molecule studies; break-junction