Naphthalene-based periodic nanoporous organosilicas: I. Synthesis and structural characterization

Novel periodic nanoporous organosilicas (PNOs) were synthesized by direct co-condensation of tetraethylorthosilicate and of the prior synthesized compound triethoxy(naphthalen-1-yl)silane. Structural characterization of materials was performed with various techniques such as 1H and 13C nuclear magnetic resonance, X-ray powder diffraction, Fourier transform infrared spectroscopy, ultraviolet–visible and photoluminescence emission and excitation spectroscopy, differential thermal and thermo-gravimetric analyses, nitrogen porosimetry and helium pycnometry. Naphthalene-based moieties were grafted on the silicate matrix through oxygen bonds resulted to novel organosilicate final materials that exhibited high naphthalene content up to 17 wt.% with a corresponding 1.33 mmol/g molar concentration, high crystallinity, specific surface area larger than 1000 m2/g and pore size distributions in the microporous/mesoporous boundary. Optical properties have been found to be comparable to the naphthalene. The attachment of the optically active part to the mesopores walls and its specific tuning for blue/UV luminescence demonstrates that this type of the reported low cost materials can be considered as phosphors in UV Leds. Tuning by using the red shift of similar larger molecules, all simultaneously trapped within the PNO, may prove to be efficient white light phosphor. Moreover, the nonlinear active properties of the active naphthalene may also allow for novel applications. Finally, materials were studied for hydrogen and methane storage with Sieverts’ apparatus and demonstrated high H2 and CH4 weight proportions for PNOs materials at various temperatures up to 4.3 MPa and 3.5 MPa respectively as presented in part II.