Direct observation of radical intermediates during electron transfer between DNA and a ternary copper complex

► On photoexcitation intra-molecular electron transfer occurs from tryptophan (Htrp) to phenanthroline (phen) within [Cu(phen)(Htrp)]ClO4. ► In presence of CT DNA a ground state complex is formed between CT DNA and ternary copper compound. ► On photoexcitation of the complex an intermolecular electron transfer occurs from DNA base to phen instead of Htrp. ► Magnetic field effect has been used to detect the triplet born radical ions in solution and in reverse micelles.