The Phosphorus Puzzle: Why Metal Phosphites Could Be the Missing Piece

It is well understood that phosphorylation of organic molecules is a keystone mechanism toward developing early cell function. However, the source of phosphorous in prebiotic chemistry is under debate. Phosphate minerals were abundant on the early Earth, but they are highly insoluble. In comparison, metal phosphites are significantly more soluble. While they may not have been preserved in the geological record, there are several plausible pathways for their formation under prebiotic conditions. We hypothesize that metal phosphites were a major source of phosphorus. To test our hypothesis, we synthesized and characterized metal phosphites, containing the most abundant cations on the early Earth (Mg2+, Ca2+, Fe2+, Fe3+). Then we reacted the metal phosphites with glycerol or propanol and looked for phosphonylated organic molecules. (n.b., Phosphonylated molecules contain a phosphite (PO33-), and phosphorylated molecules contain a phosphate (PO43-).) In nuclear magnetic resonance (NMR) experiments, we observe the formation of glycerol-a-phosphite and glycerol-b-phosphite when CaHPO3 and glycerol react at 60oC. Experiments investigating the reactivity of iron (II or III) phosphite and magnesium phosphite are ongoing.