Low temperature formation of pyridine and (iso)quinoline via neutral neutral reactions

TL;DR

This study demonstrates the gas phase formation pathways of nitrogen-containing aromatic molecules like pyridine and quinoline in extraterrestrial environments, suggesting their potential role as precursors to DNA and RNA bases.

Contribution

It provides experimental and computational evidence for the formation of key aromatic nitrogen compounds via neutral reactions at low temperatures in space.

Findings

Gas phase formation of H2CN and H2CCN radicals confirmed.

Modeling shows up to 75% synthesis of pyridine and related molecules.

Implications for prebiotic chemistry in extraterrestrial environments.

Abstract

Aromatic molecules represent fundamental building blocks in prebiotic chemistry and are contemplated as vital precursors to DNA and RNA nitrogen bases. However, despite the identification of some 300 molecules in extraterrestrial environments, the pathways to pyridine (C5H5N), pyridinyl (C5H4N), and (iso)quinoline (C9H7N) the simplest representative of mono and bicyclic aromatic molecule carrying nitrogen are elusive. Here, we afford compelling evidence on the gas phase formation of methylene amidogen (H2CN) and cyanomethyl (H2CCN) radicals via molecular beam studies and electronic structure calculations. The modeling of the chemistries of Taurus Molecular Cloud (TMC 1) and Titans atmosphere contemplates a complex chain of reactions synthesizing pyridine, pyridinyl, and (iso)quinoline from H2CN and H2CCN at levels of up to 75%. This study affords unique entry points to precursors of DNA and RNA nitrogen bases in hydrocarbon rich extraterrestrial environments thus changing the way we think about the origin of prebiotic molecules in our Galaxy.