Exploring Feed Gas Influence in Plasma–Liquid Reactions: Imine Macrocycle Formation in Chloroform.

Feed gas composition critically influences plasma–liquid chemistry; with molecular gases like air, CO₂, or CH₄, both ionised and neutral fragments can undergo reactions in the gas phase before reaching the liquid, contributing to complex downstream chemistry. In contrast, plasmas generated from atomic, and particularly inert gases, produce fewer reactive species in the gas phase, making the chemistry more traceable. This has been studied extensively in water-based systems, where the absence of molecular fragments avoids the formation of diverse secondary species. As research in plasma-assisted synthesis advances, extending such studies to non-aqueous solvents becomes increasingly relevant. In these media, gas-phase metastables may play a critical role in activating bonds and directing reactivity.

This study explores noble gas plasmas in the synthesis of imine macrocycles—a reaction shown to be accelerated by non-thermal plasma (NTP), though the mechanism remains poorly understood. Early results indicate that, despite identical plasma setups, distinct chemical outcomes arise depending on the inert gas used, suggesting a link between excited species, like metastable species, and gas-dependent reactivity. This work aims to contribute to understanding how inert feed gases influence chemistry in plasma-driven organic synthesis.