Tetraaza[14]macrocyclic Transition Metal Complexes as DNA Intercalators

Six tetraazamacrocyclic copper(II) and nickel(II) complexes have been synthesised and their interactions with double-stranded DNA (calf thymus DNA) have been studied using circular and linear dichroism, as well as other spectroscopic methods. The ability of these complexes to intercalate between DNA base pairs has been demonstrated qualitatively and confirmed by determining the stoichiometry and association constant values; these were found to range from 8.5 × 103 – 2.8 × 104 L mol–1. The nickel(II) complexes, being more electron-deficient, seem to have higher binding abilities than guests containing the copper ion. It has also been shown that not only CD, but also linear dichroism, can be a very useful tool for carrying out qualitative DNA interaction studies.