Chemiluminescence and catalysis of decomposition of dispiro(diadamantane-1,2-dioxetane) in the presence of EuIII and TbIII tris(benzoyltrifluoroacetonate) complexes

Abstract

Catalysis of decomposition of dispiro(diadamantane-1,2-dioxetane) (1) in the presence of EuIII and TbIII tris(benzoyltrifluoroacetonate) complexes (Ln(btfa)3) accompanied by the formation of adamantanone (2) and chemiluminescence (CL) was studied. The rate constants (k2) of decomposition of compound1 in the1·Ln(btfa)3 complexes and their stability constants (K1) have been determined. The Arrhenius parameters of decomposition of1 (Ea= 22.4±0.7 kcal mol−1, logA=10.2±0.8 for1·Tb(btfa)3 andEa=23.4±0.6 kcal mol−1, logA=10.6±0.8 for1·Eu(btfa)3) and thermodynamic parameters of complex formation (ΔH=−5.5±0.5 kcal mol−1, ΔS=−10.4±0.7 e.u. for1·Tb(btfa)3 and ΔH=−5.8±0.5 kcal mol−1, ΔS=−10.9±0.7 e.u. for1·Eu(btfa)3) have been calculated from the temperature dependences ofk2 andK1. The yields of excitation of the Ln(btfa)3 chelates φEu*=0.021±0.006 and φTb*=0.12±0.04 have been determined. A higher efficiency of the occupation of the5D4-level of Tb3+ compared to those of the5D1- and5D0-levels of Eu3+ is caused by different efficiencies of the non-radiative energy dissipation in the Ln3+ ion after the intracomplex energy transfer from the3n,π*-state of2 to the resonance excited levels of lanthanides.