The covalent functionalization of carbon allotropes represents a main topic in the growing field of nano materials. However, the development of functional architectures is impeded by the intrinsic polydispersibility of the respective starting material, the unequivocal characterization of the introduced functional moieties, and the exact determination of the degree of functionalization. Based on a novel carbon allotrope functionalization reaction, utilizing λ(3) -iodanes as radical precursor systems, we were able to demonstrate the feasibility to separate and to quantify thermally detached functional groups, formerly covalently linked to carbon nanotubes and graphene through thermogravimetric GC-MS.

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Dwindling fossil fuels force humanity to search for new energy production routes. Besides energy generation, its storage is a crucial aspect. One promising approach is to store energy from the sun chemically in strained organic molecules, so-called molecular solar thermal (MOST) systems, which can release the stored energy catalytically. A prototypical MOST system is norbornadiene/quadricyclane (NBD/QC) whose energy release and surface chemistry need to be understood. Besides important key parameters such as molecular weight, endergonic reaction profiles, and sufficient quantum yields, the position of the absorption onset of NBD is crucial to cover preferably a large range of sunlight’s spectrum. For this purpose, one typically derivatizes NBD with electron-donating and/or electron-accepting substituents. To keep the model system simple enough to be investigated with photoemission techniques, we introduced bromine atoms at the 2,3-position of both compounds. We study the adsorption behavior, energy release, and surface chemistry on Ni(111) using high-resolution X-ray photoelectron spectroscopy (HR-XPS), UV photoelectron spectroscopy, and density functional theory calculations. Both Br2-NBD and Br2-QC partially dissociate on the surface at ∼120 K, with Br2-QC being more stable. Several stable adsorption geometries for intact and dissociated species were calculated, and the most stable structures are determined for both molecules. By temperature-programmed HR-XPS, we were able to observe the conversion of Br2-QC to Br2-NBD in situ at 170 K. The decomposition of Br2-NBD starts at 190 K when C–Br bond cleavage occurs and benzene and methylidene are formed. For Br2-QC, the cleavage already occurs at 130 K when cycloreversion to Br2-NBD sets in.

We have investigated the anchoring of the molecular energy carrier norbornadiene (NBD) to an atomically defined oxide surface. To this end, we synthesized a carboxyl-functionalized NBD derivative, namely 1-(2′-norbornadienyl)­pentanoic acid (NBDA), and deposited it by physical vapor deposition (PVD) under ultrahigh vacuum (UHV) conditions onto a well-ordered Co3O4(111) film grown on Ir(100). In addition, we performed a comparative growth study with benzoic acid (BA) under identical conditions which was used as a reference. The interaction and orientation of NBDA and BA with the oxide surface were monitored in situ during film growth by isothermal time-resolved infrared reflection–absorption spectroscopy (TR-IRAS), both below and above the multilayer desorption temperature. The thermal behavior and stability of the films were investigated by temperature-programmed IRAS (TP-IRAS), with help of density functional (DF) calculations. BA binds to Co3O4(111) under formation of a symmetric chelating carboxylate with the molecular plane oriented nearly perpendicular to the surface. At low temperature (130 K), intact BA physisorbs in form of dimers on top of the saturated monolayer. Upon annealing to 155 K, a reordering transition is observed, in which BA in the multilayer adopts a more flat-lying orientation. The BA multilayer desorbs at 220 K, whereas the surface-anchored BA monolayer is stable up to 400 K. At higher temperature (400–550 K), desorption and decomposition are observed. Very similar to BA, NBDA binds to Co3O4(111) by formation of a symmetric chelating carboxylate. In the multilayer, which desorbs at 240 K, hydrogen-bonded NBDA dimers are formed. Upon PVD of NBDA at 300 K, only a surface anchored carboxylate is stable. The anchored NBDA film shows a characteristic restructuring behavior as a function of coverage. At low coverage the NBDA, adopts a flat-lying structure in which the norbornadiene unit interacts with the Co3O4 surface. With increasing coverage, the norbornadiene units detach from the oxide and the NBDA adopts an upright-standing orientation. Similar to BA, the anchored film is stable up to 400 K and decomposes in the temperature region between 400 and 550 K, leaving behind hydrocarbon residues on the oxide surface.

Theoretische Beschreibung von Lösungsmitteleffekten. V. Der Mediumeinfluß auf die Lactim‐Lactam‐Tautomerie von Hydroxyazinen Der Lösungsmitteleffekt auf die Tautomeriegleichgewichte der Titelverbindungen wird mit Hilfe klassischer und quantenchemischer Versionen der Solvatonen‐ und der Reaktionsfeldtheorie berechnet. In Übereinstimmung mit dem Experiment ergeben alle getesteten Verfahren eine Gleichgewichtsverschiebung zugunsten der Lactamform. Zur quantitativen Beschreibung dieses Effektes ist jedoch das Reaktionsfeldmodell besser geeignet.