Rational design of lanthanide nano periodic mesoporous organosilicas (Ln-nano-PMOs) for near-infrared emission

Abstract

We present three Periodic Mesoporous Organosilica (PMO) materials: a PMO material functionalized with pyridine dicarboxamide (DPA-PMO) and two amine functionalized PMO materials (Am-PMO and Am-ePMO). The pyridine dicarboxamide ligands in the DPA-PMO material provide the tethering sites for Ln³⁺-coordination. A Schiff base reaction was carried out on the amine functionalized PMOs to introduce similar lanthanide coordination sites. The Nd and Yb modified nano-PMOs are evaluated as near-infrared (NIR) emitting luminescent materials. The DPA-PMO and Am-ePMO materials can act as good platforms for NIR luminescence. A significant enhancement in the decay time can be observed upon grafting an Yb(hfa)₃ complex to the PMO materials instead of YbCl₃. All of the DPA-PMO@Ln(hfa)₃ and Am-ePMO@Ln(hfa)₃ materials show characteristic NIR emission performance both in the solid state and in aqueous suspension.