Femtosecond transient dynamics of a heptametallic HAT–ruthenium(II) complex. A photophysical study

A photophysical study of a heptametallic HAT–ruthenium(II) complex, {Ru(HAT)3[Ru(phen)2]6}14+ (where phen=1,10-phenanthroline and HAT=1,4,5,8,9,12-hexa-azatriphenylene), has been carried out using steady state and time resolved techniques. The absence of luminescence suggests that polycomplexation changes the properties of the Ru-bridging HAT luminophore inducing a decrease of the radiative rate constant and an enhancement of the non-radiative decay channel. By femtosecond transient absorption measurements a decay time of 1.9 ns has been measured for the 3MLCT state formed upon excitation at 590 nm. Furthermore the data give information on the relaxation processes leading to the formation of the MLCT triplet state. Upon excitaton, a single decay time of 1.4 ps has been determined. The lack of faster decays, within the instrumental time resolution, may indicate that this is a relaxation time from the Frank–Condon state produced upon excitation to the triplet MLCT state.