Novel photoactive lanthanide hybrids covalently grafted on functionalized periodic mesoporous organosilicons (PMOs) by Schiff-base derivative

Abstract

Novel functionalized periodic mesoporous organosilicons (Salen-PMOs) were synthesized by co-condensation of 1,2-bis(triethoxysilyl)ethane (BTEE) and the modified Salen-type Schiff-base compound N,N′-bis(salicylidene)ethylenediamine (Salen-Si) in the presence of Pluronic P123 surfactant as a template. N,N′-bis(salicylidene)ethylenediamine (Salen) grafted on the coupling agent 3-(triethoxysilyl)-propy-lisocyanate (TEPIC) was used as the precursor for the preparation of periodic mesoporous materials. The two kinds of resulting materials(denoted as Ln(Salen-PMOs)2 and Ln(Salen-PMOs)2phen, respectively Ln = Eu, Tb) were characterized in detail by Fourier-transform infrared spectra, ultraviolet–visible absorption spectra, small-angle X-ray diffraction, nitrogen adsorption/desorption isotherms, photoluminescence spectroscopy and luminescence decay time measurements. The results reveal that luminescent periodic mesoporous materials have high surface area, uniformity in the mesoporous structure and good crystallinity. Furthermore, the efficient intramolecular energy transfer in mesoporos material Ln(Salen-PMOs)2phen mainly occurs between the modified ligand Salen-Si and the central Eu3+ ion. In addition, the luminescent mesoporous hybrid containing terbium ions, designated as Tb(Salen-PMOs)2 and Tb(Salen-PMOs)2phen were also prepared, and were found to emit green photoluminescence characteristic of terbium ions.