Click Chemistry in Ultra‐high Vacuum – Tetrazine Coupling with Methyl Enol Ether Covalently Linked to Si(001)

Abstract

The additive-free tetrazine/enol ether click reaction was performed in ultra-high vacuum (UHV) with an enol ether group covalently linked to a silicon surface: Dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate molecules were coupled to the enol ether group of a functionalized cyclooctyne which was adsorbed on the silicon (001) surface via the strained triple bond of cyclooctyne. The reaction was observed at a substrate temperature of 380 K by means of X-ray photoelectron spectroscopy (XPS). A moderate energy barrier was deduced for this click reaction in vacuum by means of density functional theory based calculations, in good agreement with the experimental results. This UHV-compatible click reaction thus opens a new, flexible route for synthesizing covalently bound organic architectures.

Chemoselective Adsorption of Allyl Ethers on Si(001): How the Interaction between Two Functional Groups Controls the Reactivity and Final Products of a Surface Reaction

“…These two components are shifted toward higher binding energy when compared to literature reporting on carbon atoms in similar configurations; ,, this shift is attributed to the dative bond of the oxygen atom in the intact ether group of the molecule which in general shifts the position of the C 1s components to higher binding energies. , The remaining intensity can be largely reproduced by three smaller components (fits shown in red/orange) which are assigned to the reaction products after ether cleavage as shown in Figure f. The most intense component associated with this adsorption configuration (binding energy of 284.8 eV) is assigned to the C atoms present in the intact C=C double bond. ,− The component at the lowest binding energy (284.2 eV) is assigned to the carbon atom covalently bound to the silicon surface ,,,, and the peak at 286.7 eV is assigned to the carbon atom bound to an oxygen atom . The intensity ratio of these three components fits well with the assigned configuration.…”

“…The most intense component associated with this adsorption configuration (binding energy of 284.8 eV) is assigned to the C atoms present in the intact C=C double bond. 12,31−33 The component at the lowest binding energy (284.2 eV) is assigned to the carbon atom covalently bound to the silicon surface 9,12,25,33,34 and the peak at 286.7 eV is assigned to the carbon atom bound to an oxygen atom. 25 The intensity ratio of these three components fits well with the assigned configuration.…”

Tip-Induced Dissociation of Diethyl Ether on Si(001)─Influence of Molecular Structure on Final Reaction Products

“…Well-controlled functionalization of semiconductor materials on the nanoscale may open a wide range of new applications. − In this context, the reactions of organic molecules on silicon substrates are of particular interest as they bridge the fields of conventional silicon technology and organic electronics. − The latter benefits from the broad variety of functionalities available in organic chemistry. In order to better make use of the combination of these two classes of materials, the investigation of the adsorption processes of organic molecules on silicon surfaces and possible means of manipulating the adsorbates on the nanoscale play a key role.…”

Alkyne-Functionalized Cyclooctyne on Si(001): Reactivity Studies and Surface Bonding from an Energy Decomposition Analysis Perspective

“…In a second step, the bifunctional molecule can then react with further organic molecules, introducing the desired functionality. As a mechanism for the attachment of a second organic layer, click reactions [19][20][21] are a notable approach [22][23][24][25]. From a computational point of view, the presence of two reactive groups in bifunctional molecules leads to complex reactivity patterns.…”

“…Here, it is crucial that the second functional group reacts considerably slower with the surface than the cyclooctyne group to ensure selective adsorption (Figure 1). Following this recipe, several cyclooctyne derivates were experimentally and computationally designed and studied previously [18,22,23,41,[56][57][58][59].…”