Second Harmonic Generation of C₆₀Incorporated in Alkali Metal Ion Zeolites and Mesoporous MCM-41 Silica

Abstract

Different loadings of C60 have been incorporated in mesoporous MCM-41 aluminosilicate as well as proton and alkali metal ion zeolites. These samples show non-linear optics activity whose efficiency increases upon C60 content, size of the alkali metal ion, and laser exposure. The later unprecedented second harmonic generation (SHG) enhancement effect can lead up to 2 orders of magnitude efficiency increase. After having irradiated the solid, the SHG enhancement decays upon standing in the dark toward the initial value of fresh and unexposed samples. EPR measurements and alternative generation of zeolite electron−holes ions pairs have ruled out triplet excited states and radical ions as responsible for this enhancement upon irradiation. One proposal at the moment is that this SHG activity enhancement arises from unstable photoproducts such as photoadduct or dimers. However, attempts to isolate any C60-derived photoproduct have met with failure so far.

Probing microporous materials with second-harmonic generation

“…Herance et al showed that the efficiency of guest molecules to generate SHG depends on the pore dimensionality of the interconnected pore system as follows: 1D > 2D > 3D [24]. A few studies have reported the SHG-activity of host/guest assemblies in which the host structure is mesoporous silica [78][79][80]. Typically the guest species are rather large [78,79], and in one instance the SHG-active chromophore was covalently attached to the silica walls during synthesis of the porous material [79].…”

Single-walled carbon nanotubes shell decorating porous silicate materials: A general platform for studying the interaction of carbon nanotubes with photoactive molecules

“…20 Due to their channel structure, ion-exchange properties, and molecular and size recognition, many ions and molecules have been immobilized within zeolites channels. [21][22][23][24][25][26] MCM-41 is also a silicate material such as zeolites, but with larger pores and a less crystalline structure. In this work we report how to efficiently cover the external surface of silicates (Zeolite-Y and MCM-41) with different pore sizes, framework structures and aluminum content with SWCNTs (Fig.…”

Self-Assembly of C60 π-Extended Tetrathiafulvalene (exTTF) Dyads on Gold Surfaces

“…Fullerene-based materials exhibit interesting characteristics such as photovoltaic responses, superconductivity upon doping with alkali metals, nonlinear optical properties, and biological activity . Furthermore, fullerenes have frequently been used as an efficient electron acceptor component in D−A linked molecules .…”