A Study on the Florescence Characteristics of Complexes Formed by 4'-Substituted Benzo-15-Crown-5 and Europium(Ⅲ)

The fluorescene characteristics of three guest-host complexes formed by 4'-substitued benzo-15crown-5 and (Ⅲ) were reported.The sequence of the quenching ability of crown ethers to the emission of excised Eu (Ⅲ) was found to be benzo-15-crown-5 (I_s)>4'- ntiro-benzo-15-crown (I_c)>4'formyl-benzo-15-crown-5 (I_b) and an enetgy transfer process from I_b to Eu(Ⅲ) was confirmed. The utilization of the ratio of -5D₀-⁷F₂/-5D₀-⁷F₁ (ETFP/MTFP) as a measure of the substituents on benzo-crown ethers upon the fluorasence features due to the change of symmetry of the microenvironment of Eu(Ⅲ) was first proposed.