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Many organic dyes are fluorescent in solution. In the solid state, however, quenching processes often dominate, hampering material science applications such as light filters, light‐emitting devices, or coding tags. We show that the dimethylene‐cyclopropanide scaffold can be used to form two structurally different types of chromophores, which feature fluorescence quantum yields up to 0.66 in dimethyl sulfoxide and 0.53 in solids. The increased fluorescence in the solid state for compounds bearing malonate substituents instead of dicyanomethide ones is rationalized by the induced twist between the planes of the cyclopropanide core and a pyridine ligand. [ABSTRACT FROM AUTHOR]

The photochemical reaction of iodine and graphene induces strong new Raman modes due to the formation of trans‐oligoene substructures in graphene domains. This unique reactivity was demonstrated before on defect‐free graphene, however leaving the influence of e. g. carbon vacancies, unexplored. Here, we investigate the photochemical reaction applied on graphene with varying average distances of lattice defects and statistically analyze the characteristic Raman modes which develop with the iodination reaction. We show that the iodination reaction does not lead to Raman‐active defects and thus, the newly formed trans‐oligoene substructures do not contribute to the D‐mode of graphene. A statistical analysis reveals the correlation between the average distance of lattice defects and the intensity of the v1‐mode. For defective graphene with average defect distances below ~1 nm no new Raman modes evolve, which is the lower limit of the substructure size probed at 532 nm and explains why this observation was not possible before using common graphene oxide as graphene source. [ABSTRACT FROM AUTHOR]

Azafullerenes are as yet the only synthetically available heterofullerenes. Herein, we present plausible reaction pathways towards pentaaryl azafullerenes, focusing on the reactivity of hydro-azafullerene intermediates and their regiochemistry. The X-ray structure of a β′-hydro-tetraaryl adduct is presented for the first time. The reactivity of dihydro-azafullerene adducts is demonstrated here through H-abstraction in mass spectrometric experiments. Moreover, hydride abstraction and subsequent hydroxylation is possible, as well as deprotonation followed by alkylation. [ABSTRACT FROM AUTHOR]

In this study, we use our recently prepared graphene oxide (GO) with an almost intact σ-framework of carbon atoms (ai-GO) to probe the thermal stability of the carbon framework for the first time. Ai-GO exhibits few defects because CO2 formation is prevented during synthesis. Ai-GO was thermally treated before chemical reduction and the resulting defect density in graphene was subsequently determined by statistical Raman microscopy. Surprisingly, the carbon framework of ai-GO is stable in thin films up to 100 °C. Furthermore, we find evidence for an increase in the quality of ai-GO upon annealing at 50 °C before reduction. The carbon framework of GO prepared according to the popular Hummers' method (GO-c) appears to be less stable and decomposition starts at 50 °C, which is qualitatively indicated by CO2-trapping experiments in μm-thin films. Information about the stability of GO is important for storing, processing, and using GO in many applications. [ABSTRACT FROM AUTHOR]

Oxo‐graphene nanoribbons (oxo‐GNRs) can be prepared by the oxidative unzipping of single‐walled carbon nanotubes. We present an orthogonal functionalization method for the functionalization of the rims and the π‐surface, respectively, what is only possible due to the high rim portion in oxo‐GNRs. In particular, X‐ray photoelectron spectroscopy could be used to follow the reaction and detect the marker atoms contained in the addends. We propose that the reported orthogonal functionalization strategy can also be applied on other oxo‐functionalized carbon materials, such as graphene quantum dots, or reduced graphene oxide flakes. [ABSTRACT FROM AUTHOR]