Amine-containing (nano-) Periodic Mesoporous Organosilica and its application in catalysis, sorption and luminescence

In this work we introduce a novel Periodic Mesoporous Organosilica (PMO) material, where the walls of the PMO are constructed of a long linear amine precursor (3-trimethoxysilylpropyl)diethylenetriamine at 5% or 10% and 1,2-bis(triethoxysilyl)ethane. This AM-PMO is very simple to synthesize and we show that it can be used for a wide range of applications. After synthesis of the PMO, the dangling amine groups can be grafted with an aldehyde/ketone to form Schiff base ligand functionalized PMOs. Such PMOs can subsequently be reacted with lanthanide salts or lanthanide complexes yielding luminescent hybrid PMO materials. A potential application of such materials is heavy metal sensing. The AM-PMO2_nano@o-van@Eu material (o-van = o-vanilin) shows significant turn on fluorescence in the presence of Hg2+ ions. The obtained AM-PMO material was also evaluated as a heterogeneous catalyst in Knoevenagel condensation reaction. The reactions between various aldehydes and malononitrile, could proceed smoothly in the presence of AM-PMO2 presenting high conversions of 85-99% with great selectivity (> 99%). The AM-PMO additionally showed good CO2 adsorption behavior, similar to other previously reported PMOs with amine groups. However, the advantage of this material is its simplicity in preparation. In addition, the amine PMO can also be prepared in the form of nano-sized particles by altering the reaction parameters.