Hexagonal mesoporous fluorescent hybrid materials with electron acceptor viologen units in the framework

Abstract

Mesoporous MCM-41-type fluorescent hybrid materials with methylene viologen units in the framework have been synthesized via the co-hydrolysis and -condensation of dichloride of N,N′-bis(triethoxysilylmethyl)-4,4′-bipyridinium (VP) and tetraethoxysilane (TEOS). The obtained hybrid materials are characterized by the small-angle X-ray diffraction (SAXRD), high-resolution transmission electron microscope (HR-TEM), Fourier transform infrared spectrometer (FTIR), solid-state 29Si NMR spectrum, nitrogen adsorption/desorption analyse, diffuse reflectance UV–VIS (DR UV-Vis), and confocal laser scanning fluorescence microscopy (CLSFM). The results show that the VP units are covalently bonded into the silica framework to form mesoporous hybrid materials. The obtained hexagonal mesoporous hybrid materials are found to emit fluorescence at ca.380 nm and 420 nm. The fluorescent intensity enhances with increasing the amount of the VP occupied in the silica framework, and it is not affected by the hexagonal or cubic array of the pore channels. It could be prospected that such hybrid materials would present great potential applications in drug delivery and fluorescence probing for medical diagnosis and synchronous therapy.