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On‐Surface Activation of Trimethylsilyl‐Terminated Alkynes on Coinage Metal Surfaces
Author(s) -
Zhang Liding,
Zhang YiQi,
Chen Zhi,
Lin Tao,
Paszkiewicz Mateusz,
Hellwig Raphael,
Huang Tianjiao,
Ruben Mario,
Barth Johannes V.,
Klappenberger Florian
Publication year - 2019
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201900249
Subject(s) - alkyne , scanning tunneling microscope , x ray photoelectron spectroscopy , chemistry , trimethylsilyl , desorption , copper , adsorption , metal , covalent bond , molecule , surface modification , thermal desorption spectroscopy , supramolecular chemistry , photochemistry , nanotechnology , chemical engineering , materials science , organic chemistry , catalysis , engineering
The controlled attachment of protecting groups combined with the ability to selectively abstract them is central to organic synthesis. The trimethylsilyl (TMS) functional group is a popular protecting group in solution. However, insights on its activation behavior under ultra‐high vacuum (UHV) and surface‐confined conditions are scarce. Here we investigate a series of TMS‐protected alkyne precursors via scanning tunneling microscopy (STM) regarding their compatibility with organic molecular beam epitaxy (OMBE) and their potential deprotection on various coinage metal surfaces. After in‐situ evaporation on the substrates held in UHV at room temperature, we find that all molecules arrived and adsorbed as intact units forming ordered supramolecular aggregates stabilized by non‐covalent interactions. Thus, TMS‐functionalized alkyne precursors with weights up to 1100 atomic mass units are stable against OMBE evaporation in UHV. Furthermore, the TMS activation through thermal annealing is investigated with STM and X‐ray photoelectron spectroscopy (XPS). We observe that deprotection starts to occur between 400 K and 500 K on the copper and gold surfaces, respectively. In contrast, on silver surfaces, the TMS‐alkyne bond remains stable up to temperatures where molecular desorption sets in (≈600 K). Hence, TMS functional groups can be utilized as leaving groups on copper and gold surfaces while they serve as protecting groups on silver surfaces.