The influence of copper on the optical band gap of heterometallic iodido antimonates and bismuthates.

Halogenido metalates of heavy main group elements are versatile semiconductor materials with broad applications. Especially the iodido metalates generally show small optical band gaps, making them suitable for photovoltaics. However, the most promising results have been generated using toxic lead-based materials, raising environmental concerns, while the related and far less toxic bismuth compounds show band gaps too large for direct use in photovoltaics.

Surface functionalization with nonalternant aromatic compounds: a computational study of azulene and naphthalene on Si(001).

Nonalternant aromatic π-electron systems show promises for surface functionalization due to their unusual electronic structure. Based on our previous experiences for metal surfaces, we investigate the adsorption structures, adsorption dynamics and bonding characteristics of azulene and its alternant aromatic isomer naphthalene on the Si(001) surface. Using a combination of density functional theory,molecular dynamics, reaction path sampling and bonding analysis with the energy decomposition analysis for extended systems, we show that azulene shows direct adsorption paths into several, strongly bonded chemisorbed final structures with up to four covalent carbon-silicon bonds which can be described in a donor-acceptor and a shared-electron bonding picture nearly equivalently.

Relevance of π-Backbonding for the Reactivity of Electrophilic Anions [B X ] (X=F, Cl, Br, I, CN).

Electrophilic anions of type [B X ] posses a vacant positive boron binding site within the anion. In a comparatitve experimental and theoretical study, the reactivity of [B X ] with X=F, Cl, Br, I, CN is characterized towards different nucleophiles: (i) noble gases (NGs) as σ-donors and (ii) CO/N as σ-donor-π-acceptors. Temperature-dependent formation of [B X NG] indicates the enthalpy order (X=CN)>(X=Cl)≈(X=Br)>(X=I)≈(X=F) almost independent of the NG in good agreement with calculated trends.

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

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.