Abstract: The solutions of rare earth complexes Sm(Phen)₂(TTA)(Bipy)(NO₃)₃ and Sm(L)_x(TTA)_4-x(NO₃)₃[L=Phen(1,10-phenanthroline) or Bipy(2,2′-bipyridine), x=4, 3, 2, 1, 0; TTA is 2-thenoyltrifluoacetone] in EtOH(1×10^-3 mol/L) were prepared. The coefficients of antenna effect are 31.5, 18.2 and 5.6 for Phen, Bipy and TTA, respectively, when the electron configuration of the excited state of the samarium atom in the complexes is ⁴D_1/2. The fluorescent intensity and the lifetime of the supramolecular encapsulation products of (CH₃)₃Si-MCM-41 and Sm³⁺ complexes are stronger and longer than those of the encapsulation products of MCM-41 and Sm³⁺ complexes respectively. The results show that the host with lipophilic channels is more favourable to the fluorescence of the rare earth complexes than the hydrophilic mesoporous molecular sieve. The fluorescent intensity of (CH₃)₃Si-MCM-41-Sm(Phen)₃(TTA)(NO₃)₃ is the strongest amongthe encapsulation series of Sm³⁺ complexes, which is assumed to result from the greatly reduction of SiO-H vibration relaxation in host (CH₃)₃Si-MCM-41 and the presence of the discrete strong luminescent centres of the guest molecules associated with the nanosized material′s structure. The luminescent decay halftime of the supramolecular materials is much shorter than that of the powder of the samarium complexes. The result shows that the ligand transferring energy from the triplet state to the singlet state of Sm³⁺(T₁→S, intersystem crossing) becomes higher. The fluorescent experimental results indicate that the interaction between the host and the guest influences the luminescent properties of the nanostructured supramolecular materials.

Key words: MCM-41(CH₃)₃Si-MCM-41, Supramolecular system, Luminescence, Exponential decay