Excited-State N Atoms Transform Aromatic Hydrocarbons into -Heterocycles in Low-Temperature Plasmas.

The direct formation of -heterocycles from aromatic hydrocarbons has been observed in nitrogen-based low-temperature plasmas; the mechanism of this unusual nitrogen-fixation reaction is the topic of this paper. We used homologous aromatic compounds to study their reaction with reactive nitrogen species (RNS) in a dielectric barrier discharge ionization (DBDI) source. Toluene (CH) served as a model compound to study the reaction in detail, which leads to the formation of two major products at "high" plasma voltage: a nitrogen-replacement product yielding protonated methylpyridine (CHN) and a protonated nitrogen-addition (CHN) product.

Temperature-controlled electrospray ionization mass spectrometry as a tool to study collagen homo- and heterotrimers.

Collagen model peptides are useful for understanding the assembly and structure of collagen triple helices. The design of self-assembling heterotrimeric helices is particularly challenging and often affords mixtures of non-covalent assemblies that are difficult to characterize by conventional NMR and CD spectroscopic techniques. This can render a detailed understanding of the factors that control heterotrimer formation difficult and restrict rational design.