Photoluminescent and redox active periodic mesoporous organosilicas based on 2,7-diazapyrene

A novel redox-active, luminescent periodic mesoporous organosilica (PMO) based on 2,7-bis(3-trimethoxysilylpropyl)diazapyrinium diiodide (BDAP) was prepared. A 2,7-diazapyrene grafted mesoporous material (DAP-DAM-1) was also synthesized. BDAP loadings as high as 2.3% were achieved in well ordered BDAP-PMO materials. The photoluminescence properties of BDAP-PMO and DAP-DAM-1, along with a PMO based on 4,4′-bis(triethoxysilyl)-1,1′-biphenyl (BTEBp-PMO) were determined. The photoluminescence of BDAP-PMO, DAP-DAM-1, and BTEBp-PMO was quenched by nitrated explosive taggants including o-nitrotoluene, nitrobenzene, 2,3-dimethyl-2,3-dinitrobutane (DMNB), and nitromethane, suggesting the potential use of these PMOs as optical sensors for explosives. In the case of BDAP-PMO and DAP-DAM-1, exposure to nitrobenzene results in 81% quenching of fluorescence.