In situ synthesis of lanthanide complex in urea cross-linked organic/inorganic di-ureasil hybrids via carboxylic acid solvolysis

Europium complexes with 1,10-phenanthroline (phen) were in situ synthesized in the formation of di-ureasil hosts by carboxylic acid solvolysis process. The resulting luminescent hybrid materials were characterized by Fourier transforms infrared (FTIR), diffuse reflection UV–Visible (DR UV–Vis) and photoluminescence spectroscopies. The results showed that the europium complex with phen was in situ formed and exhibited the characteristic emission lines of Eu3+ ions under UV irradiation. Almost no luminescence from the host or ligand (phen) could be detected, indicating that an efficient energy transfer between the ligand and the Eu3+ ions. From the maximum crystal-filed splitting allowed for the 5D0→7F1 transition, it can be deduced that there are at least two different Eu3+-local coordination sites. The 5D0 lifetime values are around 0.23 ms and around 1.07 ms, independently of the excitation wavelength.