# Chemistry in Extreme Environments: The Mystery of Molecular Complexity in Space

## TL;DR

This paper explores how complex molecules form in space despite extreme conditions, combining lab experiments and theoretical models.

## Contribution

The paper highlights recent advances in understanding the synergy between gas-phase and grain-surface chemistry in space.

## Key findings

- Both energetic and nonenergetic processes contribute to forming complex molecules in space.
- Quantum-chemical methods combined with simulations help interpret interstellar chemical processes.
- Interstellar chemistry is still poorly understood with incomplete reaction networks and limited predictions.

## Abstract

Molecular complexity
in the interstellar medium (ISM) poses one
of the most intriguing challenges in astrochemistry: how can chemical
reactions operate efficiently under the extreme physical conditions
of space? In this Outlook, we summarize recent advances in understanding
the molecular synthesis in the ISM, emphasizing the interplay between
gas-phase and grain-surface chemistry. Laboratory studies, ranging
from gas-phase kinetics at low temperature to the irradiation of interstellar
ice analogues, demonstrate that both energetic and nonenergetic processes
contribute to the formation of complex organic and prebiotic molecules.
We discuss how accurate exploration of reactive potential energy surfaces
by means of quantum-chemical methodologies combined with kinetic simulations
provide an atomistic interpretation of the interstellar processes.
Despite the advances of the past decade, interstellar chemistry remains
in its infancy: reaction networks are incomplete, and quantitative
predictions remain limited.