“In the presence of Cu 2+ , there is a reduction in the fluorescence intensity of the DNA— daunomycin complex , at pH values above 6·0.”
“In the visible region, at pH 5·2, the addition of Cu 2+ (10 −4 M) to a denatured DNA-daunomycin complex causes a spectral shift from 505 nm to 540 and 582 nm.”