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

Catalysis of decomposition of dispiro(diadamantane-1,2-dioxetane) (1) in the presence of Eu^III and Tb^III tris(benzoyltrifluoroacetonate) complexes (Ln(btfa)₃) accompanied by the formation of adamantanone (2) and chemiluminescence (CL) was studied. The rate constants (k ₂) of decomposition of compound1 in the1·Ln(btfa)₃ complexes and their stability constants (K ₁) have been determined. The Arrhenius parameters of decomposition of1 (E _a= 22.4±0.7 kcal mol^?1, logA=10.2±0.8 for1·Tb(btfa)₃ andE _a=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 ofk ₂ andK ₁. The yields of excitation of the Ln(btfa)₃ chelates φ _Eu ^* =0.021±0.006 and φ _Tb ^* =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.