Photoparamagnetism in Solid Nucleic Acid–Cationic Dye Complexes

Abstract

USING electron paramagnetic resonance (EPR) techniques, we have demonstrated that when complexes between cationic dyes and the naturally occurring anionic polysaccharides (heparin and hyaluronic acid) or the synthetic polyanion sodium poly(ethylene sulphonate) are exposed to light, the complexes become paramagnetic. The EPR spectra showed no hyperfine splitting and the intensity of the signal was not temperature-dependent. The action of the light promotes electron transfer within the complex¹. We report here that the solid complexes between DNA, RNA and a range of cationic dyes exhibit a similar type of behaviour.