An interstellar synthesis of phosphorus oxoacids

Abstract

Phosphorus signifies an essential element in molecular biology, yet given the limited solubility of phosphates on early Earth, alternative sources like meteoritic phosphides have been proposed to incorporate phosphorus into biomolecules under prebiotic terrestrial conditions. Here, we report on a previously overlooked source of prebiotic phosphorus from interstellar phosphine (PH ₃) that produces key phosphorus oxoacids—phosphoric acid (H ₃PO ₄), phosphonic acid (H ₃PO ₃), and pyrophosphoric acid (H ₄P ₂O ₇)—in interstellar analog ices exposed to ionizing radiation at temperatures as low as 5 K. Since the processed material of molecular clouds eventually enters circumstellar disks and is partially incorporated into planetesimals like proto Earth, an understanding of the facile synthesis of oxoacids is essential to untangle the origin of water-soluble prebiotic phosphorus compounds and how they might have been incorporated into organisms not only on Earth, but potentially in our universe as well.

Abstract

Extraterrestrial sources may have provided prebiotic phosphorus to the early Earth. Here, the authors investigate the potential of phosphine-doped astrochemical analog ices to form phosphorus oxoacids as precursors to more complex prebiotic compounds.