Stability Study of Tyrosinate Radical in a Restricted Phyllomorphous Medium

Abstract

The elusive tyrosinate radical has been stabilized in the layers of synthetic laponite on intercalated tyrosinate ester molecules. According to EPR, XRD, and FT-IR data, the tyrosinate ester molecules adopt a horizontal orientation between the clay surfaces, with the aromatic rings almost perpendicular to the clay layers, giving an intersheet separation of 4.8 Å. The radical remains stable for over two months, while it is quickly reduced by nitric oxide. The observed long-term stability of the radical is due to electrostatic interactions with the negative surface of the clay as well as to sequestration phenomena which protect the radical from polymerization.