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O: Fachverband Oberflächenphysik

O 24: Semiconductor Substrates: Adsorption

O 24.2: Vortrag

Montag, 20. März 2017, 17:45–18:00, WIL C307

Chemoselective adsorption of functionalized cyclooctynes on silicon — Marcel Reutzel¹, Niels Münster¹, Marcus A. Lipponer¹, Christian Länger², Ulrich Höfer¹, Ulrich Koert¹, and •Michael Dürr² — ¹Philipps-Universität, 35037 Marburg — ²Justus-Liebig-Universität, 35392 Giessen

The high reactivity of the silicon dangling bonds presents a major hindrance for chemoselective attachment of bifunctional organic molecules on Si surfaces, the first basic reaction step for the controlled organic functionalization of silicon. Due to the high reactivity of the dangling bonds, each functional group of a bifunctional molecule adsorbs with an initial sticking coefficient close to unity and thus the final adsorption product will typically consist of a mixture of molecules adsorbed via different functional groups.

We overcome this problem employing cyclooctyne as the major building block of our strategy [1]. Using XPS and STM, cyclooctyne derivatives with different functional side groups are shown to react on Si(001) selectively via the strained cyclooctyne triple bond while leaving the side groups intact. The achieved selectivity originates from the distinctly different adsorption dynamics of the separate functionalities: A direct adsorption pathway is demonstrated for cyclooctyne as opposed to the vast majority of other organic functional groups. The latter ones react on Si(001) via a metastable intermediate, which makes them effectively unreactive in competition with the direct pathway of cyclooctyne’s strained triple bond.

[1] Reutzel et al., J. Phys. Chem. C 120 26284 (2016).