Near-infrared luminescence of periodic mesoporous organosilicas grafted with lanthanide complexes based on visible-light sensitization

A new periodic mesoporous organosilica material (named as bpd-PMO) was synthesized through co-condensation of bis(triethoxysilyl)ethane (BTEE) and a synthesized silsesquioxane precursor 4,4′-bis[Si(OEt)₃(CH₂)₄]-2,2′-bipyridine (bpd-Si) in the presence of cetyltrimethylammonium bromide (CTAB) surfactant as template. Subsequently, three near-infrared (NIR) luminescent PMO hybrid materials (named as Ln(dbm)₃bpd-PMO, Ln = Er, Nd, Yb) covalently linked with lanthanide complexes were successfully prepared via a ligand exchange reaction. The materials were characterized by XRD, N₂ adsorption–desorption isotherms, SEM, and fluorescence spectra, and the corresponding luminescent decay analyses were recorded. Of importance here is that the excitation spectra of the Ln(dbm)₃bpd-PMO extend to the visible-light range. Following the visible-light excitation, the Ln(dbm)₃bpd-PMO materials show the characteristic NIR-luminescence of the corresponding Ln³⁺ ions. The good NIR-luminescence properties of the Ln(dbm)₃bpd-PMO with the visible-light excitation would extend the potential applications of the PMO matrix to the NIR optical field.