Angle-dependent strength of a single chemical bond by stereographic force spectroscopy. Issue 19 (26th April 2022)

• Record Type: Journal Article
• Authors: Cai, Wanhao; Bullerjahn, Jakob T.; Lallemang, Max; Kroy, Klaus; Balzer, Bizan N.; Hugel, Thorsten
• Is Part Of: Chemical science. Volume 13:Issue 19(2022)
• Page Start: 5734
• Page End: 5740
• Publication Date: 2022-04-26
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d2sc01077a
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : Stereographic force spectroscopy reveals that a chemical bond ruptures along a fixed pathway such that the apparent bond strength strongly depends on the angle of force application. Abstract : A wealth of chemical bonds and polymers have been studied with single-molecule force spectroscopy, usually by applying a force perpendicular to the anchoring surface. However, the direction-dependence of the bond strength lacks fundamental understanding. Here we establish stereographic force spectroscopy to study the single-bond strength for various pulling angles. Surprisingly, we find that the apparent bond strength increases with increasing pulling angle relative to the anchoring surface normal, indicating a sturdy mechanical anisotropy of a chemical bond. This finding can be rationalized by a fixed pathway for the rupture of the bond, resulting in an effective projection of the applied pulling force onto a nearly fixed rupture direction. Our study is fundamental for the molecular understanding of the role of the direction of force application in molecular adhesion and friction. It is also a prerequisite for the nanoscale tailoring of the anisotropic strength of bottom-up designed materials.