Synthesis and optical properties of covalently bound Nile Red in mesoporous silica hybrids – comparison of dye distribution of materials prepared by facile grafting and by co-condensation routes

The fluorescence dye Nile Red (NR) can be covalently ligated to hexagonally ordered, mesoporous silica materials (MCM-41) via co-condensation and post grafting routes in order to investigate possible differences in the dye distributions. The obtained hybrid materials display emission properties similar to free NR but in contrast to free dye molecules even aqueous gels are luminescent, rendering these materials particularly interesting for biolabeling applications. All materials were structurally characterized by nitrogen sorption measurements, small angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). Their optical properties were characterized by UV/Vis and fluorescence spectroscopy.