Spectroscopic study of propargyl chloride attachment on Si(100)−2×1

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

Selective adsorption of multifunctional molecules is rarely observed when the different functional groups react via nonactivated reaction channels. Although the latter is also the case for ether cleavage and the adsorption of C=C double bonds on the highly reactive Si(001) surface, we find that allyl ethers, which combine both functional groups, react on Si(001) selectively via the cleavage of the molecules' ether group. In addition, our XPS measurements at 90, 150, and 300 K indicate an increased reactivity of the ether group when compared to monofunctional ethers. STM investigations furthermore reveal different final adsorption configurations after ether cleavage of allyl methyl ether when compared to diethyl ether as the monofunctional reference molecule. The interaction of the two functional groups in one molecule thus leads to new reaction channels with higher reactivity for ether cleavage on Si(001). As a further consequence, the reactivity of the C=C double bond is suppressed up to room temperature, leading to the observed selective adsorption.

Atom-Economical Synthesis of Lewis Acidic Boron Containing Porous Organic Polymers via Hydroboration Polymerization for Basic Chemical Capture

Atom economy is one of the main concerns for material synthesis. Here, the facile synthesis of Lewis acidic boron-containing porous organic polymers (B-POPs) via hydroboration polymerization reaction of commercially available borane dimethyl sulfide complex (BH3 ∙SMe2 ) with multi-alkynes under mild reaction conditions is presented. This new synthetic method for B-POPs has the advantage of high atom economy. The resulted porous alkenyl borane polymers (PABPs) have unique features such as high boron content, strong Lewis acidity, and high surface areas. Owing to the strong Lewis acid-base interactions, PABPs exhibit excellent adsorptive capacity toward triethylamine (up to 841 mg g-1 ) and pyridine (up to 1396 mg g-1 ) vapor.

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

The reactivity and bonding of an ethinyl-functionalized cyclooctyne on Si(001) is studied by means of density functional theory. This system is promising for the organic functionalization of semiconductors. Singly bonded adsorption structures are obtained by [2 + 2] cycloaddition reactions of the cyclooctyne or ethinyl group with the Si(001) surface. A thermodynamic preference for adsorption with the cyclooctyne group in the on-top position is found and traced back to minimal structural deformation of the adsorbate and surface with the help of energy decomposition analysis for extended systems (pEDA). Starting from singly bonded structures, a plethora of reaction paths describing conformer changes and consecutive reactions with the surface are discussed. Strongly exothermic and exergonic reactions to doubly bonded structures are presented, while small reaction barriers highlight the high reactivity of the studied organic molecule on the Si(001) surface. Dynamic aspects of the competitive bonding of the functional groups are addressed by ab initio molecular dynamics calculations. Several trajectories for the doubly bonded structures are obtained in agreement with calculations using the nudged elastic band approach. However, our findings disagree with the experimental observations of selective adsorption by the cyclooctyne moiety, which is critically discussed.

Combined XPS and DFT investigation of the adsorption modes of methyl enol ether functionalized cyclooctyne on Si(001)

The reaction of methyl enol ether functionalized cyclooctyne on the silicon (001) surface was investigated by means of X‐ray photoelectron spectroscopy (XPS) and density functional theory (DFT). Three different groups of final states were identified; all of them bind on Si(001) via the strained triple bond of cyclooctyne but they differ in the configuration of the methyl enol ether group. The majority of molecules adsorbs without additional reaction of the enol ether group; the relative contribution of this configuration to the total coverage depends on substrate temperature and coverage. Further configurations include enol ether groups which reacted on the silicon surface either via ether cleavage or enol ether groups which transformed on the surface into a carbonyl group.

Dissociative adsorption of 3-chloropropyne on Si(111)-(7 × 7): binding and structure

To achieve silicon functionalization for the development of hybrid devices, multifunctional molecules may be employed to attach to the silicon surfaces. It is important to get a fundamental understanding about the molecule/silicon interface chemistry and the binding configuration. The surface chemistry of 3-chloropropyne (HC≡C-CH(2)Cl) on the Si(111)-(7 × 7) surface, as a model system for understanding the interaction of the multifunctional molecules with a silicon surface, was studied by X-ray photoelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HREELS), and density functional theory (DFT). The 3-chloropropyne adsorbs molecularly on the silicon surface at 110 K. A chemical reaction clearly occurs such that 3-choloropropyne bonds onto the Si(111)-(7 × 7) surface at room temperature by forming C-Si linkage through the cleavage of C-Cl bond, and preserving the ethyne C≡C triple bond. This functionalized silicon surface may act as an intermediate for the growth of multiple organic layers by further attaching other functional molecules.