Ordered porous materials as media for the organization of matter on the nanoscale

Abstract

Ordered porous inorganic compounds can now be synthesized with pore sizes between 0.3 nm and several tens of nanometers. The sharp pore size distribution of such materials and the ordered pore arrangement open possibilities for using them to organize matter on the nanometer scale. This overview highlights different aspects of this topic, using four selected examples: the spatial organization of molecules with high molecular hyperpolarizability to create a frequency-doubling element; the encapsulation of a laser dye which results in a new class of solid-state lasers; the encapsulation of small metal clusters in mesoporous ordered oxides; and the encapsulation of semiconductor clusters in such oxides. #

Zeolite-Dye Microlasers

“…1. The dye molecules were brought into the pores by in situ inclusion of the organic dyes during the synthesis [24], a method pioneered by the group of Schulz-Ekloff and Wöhrle [25]. The compound was hydrothermally synthesized as described in Ref.…”

Post-Synthesis Modification I

“…Attempts to incorporate CdTe clusters directly during the synthesis of Si-MCM-41 failed in the sense that, due to the exposure to 90°C for 2 d, CdTe clusters larger than the pore widths of Si-MCM-41 were formed. This was indicated by an emission around 620 nm [384]. A broad photoluminescence spectrum, in which the luminescence arises from electrons in deep trap sites at the particle surface and defects within the confined nanoparticles, was also observed for CdSe particles in Si-MCM-41 [386].…”

“…Ihlein et al studied the preparation of CdTe clusters confined in the pores of Si-MCM-41 [384]. CdTe clusters, the color of which is determined by the particle size, show a relatively strong luminescence, which is increased when a coating with a layer of CdO reduces the number of surface traps [385].…”

“…CdTe clusters, the color of which is determined by the particle size, show a relatively strong luminescence, which is increased when a coating with a layer of CdO reduces the number of surface traps [385]. About 0.1 wt.% loading of Si-MCM-41 was achieved by impregnation from a solution of preformed CdTe clusters stabilized in 1-mercaptoglycerol [384]. Under excitation at 254 nm at room temperature, the emission maximum of this composite material was found to be similar to that of the solution around 550 nm, indicating the presence of particles with diameters of approximately 2-2.5 nm.…”

Stable CdTe nanocrystals grown in situ in thiol-modified MCM-41 mesoporous silica: Control synthesis and electrochemical detection of Cu 2+

“…In this context Vietze and coworkers studied both the adsorption of pre-formed thioglycerolcapped CdTe on MCM-41 and the growth of MCM-41 in the nanocrystal aqueous suspension [19]. Authors observed that after adsorption on MCM-41 the emission of CdTe remained practically unchanged while when incorporated during the matrix synthesis, the emission was appreciably red-shifted.…”