Picosecond transient absorption studies of dipyridophenazine

We report on ultrafast (200fs pulse durations) pump (267nm) and probe (430-700nm) studies of dipyrido -[3,2-a:2’,3’-c] phenazine (dppz) derivatives.These compounds are of interest as their metal polypyridyl complexes are used as photophysical probes for duplex DNA, where the dppz ligand can intercalate between the base pairs. Dppz, Me2dppz and F2dppz were studied to investigate changes occurring in their excited states over 1ns. In each case a transient decay and formation of a new species are seen in the 10 ®100ps region. The nature of these transients is discussed.