Self-incorporation of a luminescent neutral iridium(iii) complex in different mesoporous micelle-templated silicas

Abstract

The neutral luminescent tris-cyclometallated 2-phenylpyridine iridium(III) complex, (fac-Ir(ppy)₃, [Ir]) following a self-assembling procedure, has been successfully located in the cavities of mesostructured silica materials through a surfactant-mediated process. Two different structure-directing agents, the cationic cetyltrimethyl ammonium bromide (CTAB) and the non-ionic poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (P123) were tested. The structural features induced by the metal complex incorporation can be explained by comparing the newly synthesized hybrid mesostructured materials with the corresponding undoped samples which were similarly prepared. X-Ray powder diffraction (XRD), nitrogen sorption, scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and UV-Vis spectroscopy were used to characterize the investigated materials. Medium-sized spherical particles of 800 nm were obtained using CTAB as a structure-directing agent whereas larger monolithic aggregates with a minimum dimension of 5–8 μm were obtained using P123. The new hybrids showed the typical hexagonal symmetry of analogously prepared materials. Moreover high luminescence quantum yield values were obtained for both hybrids as a result of a very good dispersion of the chromophore in the mesostructured matrices, thereby avoiding dramatic self-quenching phenomena. The approach described in this paper provides a simple synthetic way to prepare new luminescent silica-based materials by the inclusion of neutral metal-containing luminophores into the pores of a mesoporous hosting skeleton.