Prebiotic Chemistry of Phosphite: Mild Thermal Routes to Form Condensed-P Energy Currency Molecules Leading Up to the Formation of Organophosphorus Compounds

Abstract

The in-fall of meteorites and interstellar dust particles during the Hadean–Archean heavy bombardment may have provided the early Earth with various reduced oxidation state phosphorus compounds and minerals, including phosphite (HPO32−)([Pi(III)]). The ion phosphite ([Pi(III)])has been postulated to be ubiquitous on the early Earth and consequently could have played a role in the emergence of organophosphorus compounds and other prebiotically relevant P species such as condensed P compounds, e.g., pyrophosphite ([PPi(III)]) and isohypophosphate ([PPi(III–V)]). In the present study, we show that phosphite ([Pi(III)]) oxidizes under mild heating conditions (e.g., wet–dry cycles and a prebiotic scenario mimicking a mildly hot-evaporating/drying pool on the early Earth at 78–83 °C) in the presence of urea and other additives, resulting in changes to orthophosphate ([Pi(V)]) alongside the formation of reactive condensed P compounds (e.g., pyrophosphite ([PPi(III)]) and isohypophosphate ([PPi(III–V)])) through a one-pot mechanism. Additionally, we also show that phosphite ([Pi(III)]) and the condensed P compounds readily react with organics (nucleosides and organic alcohol) to form organophosphorus compounds.