Stable and metastable forms of poly(G)

Poly(G) is shown by ir spectroscopy to be capable of existence in a metastable form which is converted spontaneously at ambient temperature, or more rapidly on heating, to a stable form. The metastable form can be regenerated by freezing and thawing the solution. The high‐charge density of four‐stranded poly(G) makes it especially susceptible to electrostatic destabilization by use of Et 4 N + counterions, which screen electrostatic repulsion of multiple strands less effectively than alkali metal ions. Poly(G) has been obtained for the first time in the single‐stranded form in aqueous solution and shown to undergo a fully reversible helix–coil transition on heating.