Functionalization of Diamond(100) by Cycloaddition of Butadiene: First-Principles Theory

A first principles study of H2S adsorption and decomposition on a Ge(100) surface

We employed density functional theory (DFT) calculations to examine the adsorption configurations and possible reaction paths for H₂S on a Ge(100) surface.

A HREELS and DFT study of the adsorption of aromatic hydrocarbons on diamond (111)

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.

Functionalization of the semiconductor surfaces of diamond (100), Si (100), and Ge (100) by cycloaddition of transition metal oxides: a theoretical prediction

The viability of functionalization of the semiconductor surfaces of diamond (100), Si (100), and Ge (100) by traditional [3 + 2] cycloaddition of transition metal oxides has been predicted using effective cluster models in the framework of density functional theory. The cycloaddition of transition metal oxides (OsO(4), RuO(4), and MnO(4)(-)) onto the X (100) (X = C, Si, and Ge) surface is much more facile than that of other molecular analogues including ethylene, fullerene, and single-walled carbon nanotubes because of the high reactivity of surface dimers of X (100). Our computational results demonstrate the plausibility that the well-known [3 + 2] cycloaddition of transition metal oxides to alkenes in organic chemistry can be employed as a new type of surface reaction to functionalize the semiconductor X (100) surface, which offers the new possibility for self-assembly or chemical functionalization of X (100) at low temperature. More importantly, the chemical functionalization of X (100) by cycloaddition of transition metal oxides provides the molecular basis for preparation of semiconductor-supported catalysts but also strongly advances the concept of using organic reactions to modify the solid surface, particularly to modify the semiconductor C (100), Si (100), and Ge (100) surfaces for target applications in numerous fields such as microelectronics and heterogeneous photocatalysis.

Formation and characterization of organic monolayers on semiconductor surfaces

Organic-semiconductor interfaces are playing increasingly important roles in fields ranging from electronics to nanotechnology to biosensing. The continuing decrease in microelectronic device feature sizes is raising an especially great interest in understanding how to integrate molecular systems with conventional, inorganic microelectronic materials, particularly silicon. The explosion of interest in the biological sciences has provided further impetus for learning how to integrate biological molecules and systems with microelectronics to form true bioelectronic systems. Organic monolayers present an excellent opportunity for surmounting many of the practical barriers that have hindered the full integration of microelectronics technology with organic and biological systems. Of all the semiconductor materials, silicon and diamond stand out as unique. This review focuses upon the preparation and characterization of organic and biomolecular layers on semiconductor surfaces, with special emphasis on monolayers formed on silicon and diamond.

Density Functional Theory Investigation of Product Distribution following Reaction of Acrylonitrile on Diamond (001)-2×1 Surface

The reaction of acrylonitrile with the C(001)-2 x 1 surface has been investigated by employing density functional cluster model calculations. The calculations revealed eight possible reaction pathways for acrylonitrile with the surface dimer. Full geometry optimized structures were obtained for all adducts, including intra- and interdimer reaction products. These results were analyzed in terms of both the total energy values and the detailed optimized geometries. We find that the reaction of acrylonitrile with the diamond (001) surface occurs primarily through its nonpolar C=C group and the intradimer [2+2](cc) product is the dominant product. All these results are in good agreement with the experimental work by Schwartz. It is noteworthy that the isomerization process plays an important role in the chemisorption process. Both intradimer [4+2] product and interdimer [2+2](cc) product can isomerize to the intradimer [2+2](cc) product. The present study shows that the isomerization between intradimer [4+2] product and intradimer [2+2](cc) product is slightly favorable over the direct path to formation of the intradimer [2+2](cc) product.

The Cycloadditions of Various Substituted Carbenes, Silylenes, and Germylenes onto the Diamond (100) Surface: A Theoretical Exploration

The cycloadditions of 21 singlet substituted carbenes, silylenes, and germylenes onto the diamond (100) surface have been theoretically studied by means of density functional theory coupled with effective cluster models. The calculated reaction energies and reaction pathways have disclosed that the substituents play an important effect on the reaction profiles for the additions of carbenes, silylenes, and germylenes onto the diamond (100) surface. Our theoretical investigations illustrate that, irrespective of carbenes, silylenes, and germylenes, the cycloadditions of those with electropositive substituents (such as H and CH(3)) onto diamond (100) are much more favorable than those with electronegative and pi-donating substituents (such as F and NH(2)) both thermodynamically and kinetically. In broad perspective, we believe that a similar reactivity trend can also be extended to that of Si (100), Ge (100), fullerene, single-walled carbon nanotube, disilenes, digermenes, silenes, and germenes because all of these materials feature an analogous bonding motif.

Mechanism and Regioselectivity for the Reactions of Propylene Oxide with X(100)-2×1 Surfaces (X = C, Si, Ge): A Density Functional Cluster Model Investigation

We have performed density functional cluster model calculations to explore the mechanism and regioselectivity for the reactions of propylene oxide with X(100)-2x1 surfaces (X = C, Si, and Ge). The computations reveal the following: (i) the reactions on Si(100) and Ge(100) are barrierless and highly exothermic; (ii) the reactions on X(100) (X = Si and Ge) are initiated by the formation of a dative-bonded precursor state followed by regioselective cleavage of the C2-O bond (C2 directly connected to the methyl-substituent) in propylene oxide, giving rise to a five-membered ring surface species; and (iii) the reaction on C(100), although highly exothermic, requires a large activation energy and would be kinetically forbidden at room temperature.

Predicting Facile Epoxidation of the Diamond (100) Surface by Dioxiranes and Subsequent Ring-Opening Reactions with Nucleophiles

By means of density functional theory coupled with effective cluster models, we have theoretically predicted the viability of epoxidation of the diamond (100) surface by organic dioxiranes. In addition, subsequent ring-opening reactions of the as-formed epoxide surface species with some nucleophiles, including water, ammonia, and alcohol, have also been explored. The facile epoxidation of diamond (100) by dioxiranes presents a new alternative for oxidation of the diamond (100) surface. More importantly, the as-formed epoxide-like surface species would be a useful springboard for further functionalizations of the diamond surface given the well-known abundant chemistry of organic epoxides. Therefore, this approach provides another new route to chemical functionalization of the diamond surface, which is potentially useful for leading to the improvement of diamond behavior and constructing new hybrid diamond-based materials for wide potential applications in many fields. In perspective, implications for other theoretical work are also discussed.

Organic functionalization of the Si (100) and Ge (100) surfaces by cycloadditions of carbenes and nitrenes: a theoretical prediction

By means of density functional theory (B3LYP/6-31G*) coupled with effective cluster models, we predict that the well-known cycloaddition reactions of carbenes and nitrenes to alkenes in organic chemistry can be employed as a new type of surface reaction to organically functionalize the Si (100) and Ge (100) surfaces at low temperature. The well-established abundance of carbenes and nitrenes addition chemistry in organic chemistry provides versatile flexibility of functionalizing the surfaces of Si (100) and Ge (100), which can potentially impart new organic functionalities to the semiconductors surface for novel applications in a diversity of fields. Our predictions strongly advance the concept of using organic reactions to modify the solid surface in a controlled manner and quite intriguing chemistry can lie in the material featuring the analogous bonding motif. In further perspective, implications for other theoretical work, regarding disilenes, digermenes, silenes, and germenes that all feature the bonding motif similar to alkenes, are also discussed.

Functionalization of diamond (100) by organic cycloaddition reactions of nitrenes: a theoretical prediction

[structure: see text] We predict the viability of organic cycloadditions of nitrenes onto the diamond (100) surface. This new type of surface reaction can be employed to functionalize diamond surface at low temperature, which might introduce new functionalities to the diamond surface for novel applications in a diversity of fields.

Organic functionalization of diamond (100) by addition reactions of carbene, silylene, and germylene: a theoretical prediction

We present a theoretical prediction of the facile cycloadditions of carbene, silylene, and germylene onto the diamond (100) surface, a new type of surface reaction that can be employed to functionalize diamond surface at low temperature. This finding renders the plausibility that the diamond surface can be chemically modified by the well-known carbene addition chemistry, which might introduce new functionalities to the diamond surface for novel applications in a diversity of fields.

Hydroboration of C(100) surface, fullerene, and the sidewalls of single-wall carbon nanotubes with borane

Hydroboration of three allotropes of carbon, i.e., diamond (100) surface, [60]fullerene, and single-wall carbon nanotubes (SWNTs), with borane (BH(3)) has been explored by means of quantum chemical calculations. The calculations predicted that the hydroboration of C(60) and the C(100)-2x1 surface occurs readily, whereas the hydroboration of the sidewall of an armchair (5,5) SWNT is thermoneutral with a barrier height of 11.5 kcal/mol. This suggests that sidewall hydroboration, if viable, would be highly reversible on the (5,5) SWNT. The as-hydroborated carbonous materials can be good starting points for further chemical modification and manipulation of these carbonous materials, given the abundant chemistry of organoboranes.

Competition and selectivity of organic reactions on semiconductor surfaces: reaction of unsaturated ketones on Si(100)-2 x 1 and Ge(100)-2 x 1

A combined experimental and theoretical study of a model system of multifunctional unsaturated ketones, including ethyl vinyl ketone (EVK), 2-cyclohexen-1-one, and 5-hexen-2-one, on the Si(100)-2 x 1 and Ge(100)-2 x 1 surfaces was performed in order to probe the factors controlling the competition and selectivity of organic reactions on clean semiconductor surfaces. Multiple internal reflection infrared spectroscopy data and density functional theory calculations indicate that EVK and 2-cyclohexen-1-one undergo selective [4 + 2] hetero-Diels-Alder and [4 + 2] trans cycloaddition reactions on the Ge(100)-2 x 1 surface at room temperature. In contrast, on the Si(100)-2 x 1 surface, evidence is seen for significant ene and possibly [2 + 2] C=O cycloaddition side products. The greater selectivity of these compounds on Ge(100) versus Si(100) is explained by differences between the two surfaces in both thermodynamic factors and kinetic factors. With 5-hexen-2-one, for which [4 + 2] cycloaddition is not possible, a small [2 + 2] C=C cycloaddition product is observed on Ge(100) and possibly Si(100), even though the [2 + 2] C=C transition state is calculated to be the highest barrier reaction by several kilocalories per mole. The results suggest that, due to the high reactivity of clean semiconductor surfaces, thermodynamic selectivity and control will play important roles in their selective functionalization, favoring the use of Ge for selective attachment of multifunctional organics.

A DFT study of the 1,3-dipolar cycloadditions on the C(100)-2 x 1 surface

The 1,3-dipolar cycloadditions (1,3-DCs) of a series of 1,3-dipolar molecules onto the C(100)-2 x 1 surface have been investigated by means of hybrid density functional B3LYP method in combination with cluster model approach. It was found that 1,3-DCs on the C(100)-2 x 1 surface are more favorable over their molecular analogues both thermodynamically and kinetically. The enhancement of the reactivity on the surface due to the reduced overlap between the p(pi) orbitals of the surface C=C dimer should be important for the semiconductor industry because it might lead to a breakthrough in the fabrication of diamond films at low temperature.