Importance of the Anchor Group Position (Para versus Meta) in Tetraphenylmethane Tripods: Synthesis and Self-Assembly Features

• Published in: Chemistry : a European journal Vol. 22; no. 37; pp. 13218 - 13235
• Main Authors: Lindner, Marcin, Valášek, Michal, Homberg, Jan, Edelmann, Kevin, Gerhard, Lukas, Wulfhekel, Wulf, Fuhr, Olaf, Wächter, Tobias, Zharnikov, Michael, Kolivoška, Viliam, Pospíšil, Lubomír, Mészáros, Gábor, Hromadová, Magdaléna, Mayor, Marcel
• Format: Journal Article
• Language: English
• Published: WEINHEIM Blackwell Publishing Ltd 05.09.2016; Wiley; Wiley Subscription Services, Inc
• Subjects: Anchors; Chemistry; Chemistry, Multidisciplinary; Derivatives; Gold; Low temperature; molecular tripods; monolayers; Physical Sciences; Platforms; scanning probe microscopy; Science & Technology; Self assembly; Spectroscopy; Spectrum analysis; Surface chemistry; Synthesis; tetraphenylmethane; Tripods; X-ray absorption spectroscopy; X-rays; monolayers; COVALENT ORGANIC FRAMEWORK; MOLECULAR MOTORS; tetraphenylmethane; molecular tripods; GOLD SURFACES; scanning probe microscopy; ELECTRON-TRANSFER; AU; SPECTROSCOPIC CHARACTERIZATION; BETA-CYCLODEXTRIN; X-ray absorption spectroscopy; TAIL GROUP; RESONANT EXCITATION
• ISSN: 0947-6539; 1521-3765; 1521-3765
• DOI: 10.1002/chem.201602019

The efficient synthesis of tripodal platforms based on tetraphenylmethane with three acetyl‐protected thiol groups in either meta or para positions relative to the central sp3 carbon for deposition on Au (111) surfaces is reported. These platforms are intended to provide a vertical arrangement of the substituent in position 4 of the perpendicular phenyl ring and an electronic coupling to the gold substrate. The self‐assembly features of both derivatives are analyzed on Au (111) surfaces by low‐temperature ultra‐high‐vacuum STM, high‐resolution X‐ray photoelectron spectroscopy, near‐edge X‐ray absorption fine structure spectroscopy, and reductive voltammetric desorption studies. These experiments indicated that the meta derivative forms a well‐ordered monolayer, with most of the anchoring groups bound to the surface, whereas the para derivative forms a multilayer film with physically adsorbed adlayers on the chemisorbed para monolayer. Single‐molecule conductance values for both tripodal platforms are obtained through an STM break junction experiment. Tripod architectures: The film‐forming properties of tripodal tetraphenylmethanes are determined by the choice of the anchor group positions (see figure). The self‐assembly features and properties of both meta and para derivatives are analyzed through a range of techniques.