Tuning porphyrin/DNA supramolecular assemblies by competitive binding

Addition of an intercalating but nonaggregating porphyrin, AuT4, to a preformed adduct between DNA and a strongly aggregating porphyrin, t-H2Pagg, permits control of the extent of aggregation of the latter. The size and the intensity of the ICD and RLS signals depend linearly on the concentration of the intercalating dye and decrease markedly on increasing the concentration of the available binding sites on the biopolymer template.