Triplet energy transfer in photoexcited diketone

The rate at which excitation energy transfers between chromophores of diketones was investigated. Energy transfer (ET) was induced by irradiation of the diketones with 313nm and 366nm ultraviolet light. The most significant aspect of this work is the assignment of rates for both exothermic and endothermic ET between the chromophores of a diketone molecule. By varying the most influential factors which determine ET rates, the difference in energy between the triplet excited states of each chromophore ($Delta$E) and the length of the alkyl tether linking the chromophores, two trends emerged. First, as the $Delta$E increased between two interacting chromophores within a given bichromophoric series of compounds, exothermic ET increased and endothermic ET decreased. Second, as the alkyl tether length connecting the two chromophores increased, both the exothermic and endothermic ET rates decreased. Intramolecular ET rates were derived by fitting the experimental photokinetic data with mathematical models.