THE MECHANISM OF THE <b>9</b>,10‐DIBROMOANTHRACENE MEDIATED TRIPLET‐SINGLET ENERGY TRANSFER IN THE TETRAMETHYL‐<b>1</b>,2‐DIOXETANE ENERGIZED RUBRENE LUMINESCENCE*

Abstract

Abstract— The ternary chemiluminescent system consisting of tetramethyl‐dioxetane (TMD), 9 ,10‐dibromoanthracene (DBA) and rubrene (Ru) has been investigated in benzene solution and in polystyrene matrices. DBA has been found to mediate the energy transfer between excited triplet acetone ( 3 K), generated from TMD, and rubrene resulting in the enhancement of the Ru emission and reduction in the DBA emission. A detailed kinetic analysis confirms that ca. 50% of the enhanced chemilumines‐cence involves triplet‐singlet (TS) energy transfer from 3 K to DBA, followed by singlet‐singlet (SS) energy transfer from DBA to Ru, the remainder ca. 50% being due to reabsorption of DBA fluorescence by rubrene. It is concluded that the TS energy transfer is of the resonance type, occurring with a rate of k TS K.DBA = (1.4 ± 0.4) ± 10 9 M ‐1 s ‐1 and an efficiency of ø TS K.DBA = 0.3 ± 0.1. As expected, the SS energy transfer is also of the resonance type, taking place at comparable rates in benzene solution and in polystyrene matrices, is. k SS DBARU = 1.5 ± 10 10 M ‐1 and (2.2 ± 0.2) ± 10 10 M ‐1 s ‐1 , respectively.