Fluorescent mesoporous organosilicas containing 1,4-diureyl terephthalate moieties

• Three different synthesis routes for fluorescent organosilicas.
• Fluorescent bis-silylated precursor immobilized on mesoporous materials.
• Synthesis of new fluorescent PMO containing 1,4-diureyl terephthalate moiety.
• Co-condensation method to prepare fluorescent ordered mesoporous organosilica.

New fluorescent organosilicas were obtained starting from the incorporation of fluorescent dye diethyl 2,5-bis[N,N-(3-triethoxysilyl)propylurea]terephthalate (BT) in ordered mesoporous silica and in xerogel silica by three different synthesis routes: post-grafting in SBA-15 (BTG), simultaneous co-condensation of TEOS and BT dye in presence of structure directing agents (BTC) and sol–gel method (BTX). These hybrid materials were characterized by nitrogen adsorption/desorption isotherms, X-ray diffraction (XRD), transmission (TEM) and scanning electron microscopy (SEM), UV–vis diffuse reflectance and fluorescence spectroscopy. All materials showed interesting textural properties such as high surface area and mesoporosity. The BTC and BTG silica showed unimodal pore size distribution and hexagonal organized pore structure, with pore size presenting average diameters near to 6.0 nm. The photophysical behavior of BT dye in ordered and non-ordered hybrid materials is very similar to those recorded in diluted ethanol solution. This means that the structure of the dye was maintained after the insertion in the silica matrix and the dye molecules are surrounded by the silanol groups. All synthesis methods applied in this work showed to be efficient in the preparation of fluorescent materials in which the ordered or disordered mesoporosity is maintained even with the insertion of organic fluorescent group, enlarging the possibility of applications as optical sensors.

Figure optionsDownload as PowerPoint slide