Knowledge Bank

Jet-FTIR spectroscopy is a powerful technique to investigate small hydrogen bonded clusters} \textbf{118}, 2001, 331--359.}. The filet-jet-spectrometer combines a $600\times 0.2$,mm\textsuperscript{2} slit nozzle with a commercial FTIR-instrument} \textbf{219}, 2005, 379--388.}.\ Pyrrole is a five-membered heterocyclic aromat with hydrogen bond donor (N--H) and acceptor ($\pi$-system) functionalities. Weak \mbox{N--H$\cdots \pi$} hydrogen bonds} \textbf{108}, 2004, 6953--6967.} play an important role in biological systems. Therefore, weakly bound aggregates of pyrrole and some of its methylated derivatives have been systematically characterised by the filet-jet-spectroscopy.\ In pyrrole-2-carboxaldehyde, the additional carbonyl group offers a better hydrogen bond acceptor site and leads to the formation of more conventional N--H$\cdots$O hydrogen bonds. Its dimer has therefore been investigated as a small model system for hydrogen bonding in peptides.