A HREELS and DFT Study of the Adsorption of Aromatic Hydrocarbons on Diamond (111)

Abstract

Ultrathin layers of organic molecules can be assembled on group IV (e.g., silicon, germanium, diamond) semiconductor surfaces using surface analogues of cycloaddition reactions. We present a study of the chemisorption of benzene, toluene, and styrene on the Pandey chain of C(111) using high resolution electron energy loss spectroscopy and density functional theory calculations. Two cycloaddition reactions, namely, the [4 + 2] and [2 + 2], were examined. The [4 + 2] reaction is found to be thermodynamically unfavorable on C(111), while the [2 + 2] reaction involving the ring is slightly exothermic. In the case of aromatic molecules with an external unsaturated functional group, the reaction can proceed via the external functionality, thereby preserving the aromatic ring and providing further stability. Different reactivity patterns to the C(100) surface are rationalized on the basis of steric effects imposed by the geometrical structure of the Pandey chain. Our study demonstrates the potential of employing the Pandey chain as a template for assembling one-dimensional molecular structures on the diamond surface.

Interfacial Adhesive Properties between a Rigid-Rod Pyromellitimide Molecular Layer and a Covalent Semiconductor via Atomistic Simulations

“…Further progress in the device packaging and coating technology requires a deeper understanding of the processes that control structural developments within the interfacial layer of polyimide deposited on chemically dissimilar substrates, that is, inorganic materials. To date, nearly all theoretical studies of adhesion-related phenomena for organic matter deposited on covalent semiconductors, have focused either on single-molecule physi- or chemisorption, treated using advanced quantum chemistry methods − or development of various continuum elasticity/mechanics-based approaches to the problem of adhesion. − While the former approaches provide detailed and precise information about the corresponding systems, they lack the desired level of robustness and predictive capabilities for realistic-size systems. This is, largely, because of (1) limitations in system size (few hundreds atoms, at best) and because (2), until recently, quantum mechanical approaches have not included van der Waals (vdW) interactions, even though these appear to dominate interface energetics of bimaterials comprised of a soft organic polymer and a covalent solid.…”

“…However, the existing theoretical framework is not suitable for materials with significant vdW contributions. On the other hand, the continuum-level treatments − do not adequately incorporate all microscopic details of the interfaces, that is, they treat interfaces in an oversimplified manner, especially concerning the relationship between interface microstructure and energetics. All of the above suggests that there is a need to further our understanding of adhesive behavior via the development of theoretical and simulation-based models, specifically concerning bimaterial systems in which soft organic and covalently bonded inorganic constituents are paired.…”

Direct Functionalization of Nanodiamonds with Maleimide

“…Further derivatization with functional substituents can be achieved by catalyzed cross-coupling at the aryl site. As an alternative, functional aryls can also be appended to diamond films (e.g., via cycloadditions, [4 + 2] or [2 + 2]) − and to the π-system of thermally annealed nanodiamonds, , albeit using specific reagents and elevated temperature conditions . Here, we report on a protocol of direct functionalization by which maleimide-derivatized substituents can be appended to the outer shell of thermally annealed nanodiamonds under ambient conditions.…”