Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 6: Organic Molecules on Inorganic Substrates I: Electronic, Optical and other Properties

O 6.11: Talk

Monday, March 16, 2020, 13:15–13:30, REC C 213

Investigation of a Novel Tetrapodal Self-Assembled Monolayer for Orthogonal Orientation — •Valentina Rohnacher^1,2, Frank S. Benneckendorf^2,3, Sebastian Beck^1,2, Jan Freudenberg^2,3, Wolfram Jaegermann^2,4, Paolo Samorì⁵, Michael Zharnikov⁶, Uwe H.F. Bunz^2,3, Annemarie Pucci^1,2, and Klaus Müllen^2,7 — ¹KIP, Uni Heidelberg — ²InnovationLab, Heidelberg — ³TU Darmstadt — ⁴OCI, Uni Heidelberg — ⁵CNRS, Uni Strasbourg — ⁶PCI, Uni Heidelberg — ⁷MPIP, Mainz

Conformationally rigid multipodal molecules should control the orientation and packing density of functional head groups upon self-assembly on solid supports. Common tripods frequently fail in this regard, because of inhomogeneous bonding configuration and stochastic orientation. These issues are circumvented by a suitable tetrapodal diazatriptycene (DAT) moiety, bearing four thiol-anchoring group.
We performed infrared reflection-absorption spectroscopy (IRRAS) on DAT molecules assembled on gold substrates to probe the orientation. Together with the results of contact angle measurements, STM, NEXAFS and PES, a better understanding about the formation of self-assembled monolayers (SAMs) was achieved. We found out that DAT molecules form well-ordered SAMs on Au(111) substrates, whereby the tetrapodal scaffold enforces a nearly upright orientation of the terminal head group with respect to the substrate. Functionalization by condensation chemistry allows a large variety of functional head groups to be introduced to the tetrapod, paving the path towards advanced surface engineering and sensor fabrication.