# Cosmic Silicate Surfaces Catalizing Prebiotic Reactions: Atomistic Modeling on the Polymerization of HCN

## TL;DR

This study shows how silicate surfaces in space can catalyze the formation of complex organic molecules from hydrogen cyanide, potentially aiding the emergence of life.

## Contribution

The study reveals how Mg-rich silicate surfaces catalyze HCN polymerization using atomistic simulations, showing lowered activation barriers and feasible reaction conditions.

## Key findings

- Mg2SiO4 surfaces lower HCN polymerization activation barriers by ∼120–220 kJ mol–1.
- Reactions are feasible above 300 K on asteroids and planetary surfaces.
- Water enhances reaction steps by aiding proton transfer.

## Abstract

Hydrogen cyanide,
HCN, is a fundamental building block in astro-
and cosmochemical environments, known for its ability to form prebiotically
relevant molecules such as nucleobases. Although its polymerization
is inhibited under the cold, dilute conditions of the interstellar
medium, the higher temperatures of more evolved rocky bodies, combined
with the presence of mineral surfaces, can catalyze the reaction.
In this study, we use atomistic simulations grounded on the density
functional theory (DFT) to elucidate the complete tetramerization
pathway of HCN to diaminomaleonitrile (DAMN) and diaminofumaronitrile
(DAFN), catalyzed by the crystalline Mg2SiO4 forsterite (120) surface. Results demonstrate that the intrinsic
acid–base properties of the surface facilitate chemical bond
formation/cleavage needed for HCN oligomerization, lowering activation
barriers by ∼120–220 kJ mol–1 with
respect to the gas-phase. Kinetic analyses reveal that the reactions
are feasible at temperatures above 300 K, particularly under conditions
present in warm, rocky bodies such as asteroids, meteorites, and planetary
surfaces. The presence of water further accelerates key steps by assisting
proton transfer processes. These findings support a model in which
Mg-rich silicate minerals (abundant in the early Solar System) may
have directly catalyzed the formation of complex organic molecules,
which, in turn, are precursors of more complex biomolecules, thereby
contributing to the essential chemical inventory for the emergence
of life on early Earth and other primitive planets with propitious
conditions.