Abstract
The phosphorescent properties of closed shell metal chelates have been studied in EPA at 77°K. The compounds investigated include the acetylacetonates of magnesium and Group III-A metal ions (Al, Ga, In) as well as the trifluoroacetylacetonate and hexafluoroacetylacetonate chelates of aluminum. The results indicate that although the metal center does not greatly affect the position or vibronic structure of the acetylacetonate luminescence it is important in both intersystem crossing and radiative coupling to the ground state in these systems. It is also concluded that there is little or no interaction between the ligand rings in the emitting triplet state. Altering the electron distribution in the ligand ring by successively replacing the −CH 3 groups with −CF 3 groups results in a red shift in the location of the emission and a marked alteration in the vibronic envelope. The luminescence of single crystals of aluminum, indium and gallium acetylacetonate has also been investigated. All three crystals exhibit a broad, short-lived emission which is assigned as fluorescence from an excimer-like configuration.
Published Version
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