Spectroscopic Studies of Colloidal Solutions of Nanocrystalline Ru(bpy)₃²⁺−Zeolite Y

Abstract

Preparation of suspensions of Ru(bpy) 3 2+ -zeolite Y has made it possible to use conventional optical transmission spectroscopic methods to examine the entrapped Ru(bpy) 3 2+ species within the zeolite. To prepare the suspensions, the surface hydroxyl groups of nanocrystalline zeolite Y were silylated using noctadecyltrichlorosilane. The hydrocarbon sheath on the surface of the zeolites prevented agglomeration of the particles and made the surface hydrophobic enough for dispersion in toluene. The spectroscopic properties of the entrapped Ru(bpy) 3 2+ were measured via transmission techniques. For low levels of zeolite in the suspension (1 mg/10 mL), the scattering was low, and the absorption and fluorescence spectra of Ru(bpy) 3 2+ -entrapped zeolite Y were quantitatively identical to the solution spectra with comparable Ru(bpy) 3 2+concentrations. This suggests that all of the Ru(bpy) 3 2+ inside the zeolite is being sampled and the extinction coefficient of the complex is not altered upon incorporation inside the zeolite. The nature of the quenching mechanism in the Ru(bpy) 3 2+-viologen-zeolite Y system was studied by steady-state fluorescence and lifetime measurements, and it was determined to be mostly due to static quenching. Intrazeolitic electron transfer from the photogenerated viologen radical to Ru(bpy) 3 3+ was followed by flash photolysis, and information about the dynamics of the electron-transfer process was obtained. Comparison of the electron-transfer and quenching data with previous studies on zeolite samples examined by diffuse reflectance methods led to the conclusion that, in reflectance measurements, mostly the surface of the zeolite is sampled. The suspensions, on the other hand, provide a method to examine molecules inside the crystal. Overall, this study demonstrates that zeolite-entrapped complexes can be examined using transmission spectroscopic techniques by using nanocrystalline zeolites with modified surfaces.

Synthesis of high-quality nanocrystalline zeolite Y using pseudoboehmite as aluminum source

“…Nanocrystalline zeolites had higher external surface area and shorter diffusion path than the micrometer-sized zeolites, which made the former be promising catalytic materials and adsorbents [1][2][3][4][5][6][7]. Zeolite Y has been extensively used in ion exchangement, adsorption, catalysis and other aspects.…”

“…Zeolite Y has been extensively used in ion exchangement, adsorption, catalysis and other aspects. Recently, there has been a great deal of interest in synthesis and application of nanocrystalline zeolite Y [6,[8][9][10][11].…”

Time-resolved photoluminescence analysis of distribution and migration of terbium ions in zeolites X

“…Alternative approaches in the analysis of the PL decays will be based on the Albery's dispersed kinetics model [38] or the maximum entropy method [39]. The first method was already applied to the emission lifetimes of Ru(bpy) 2+ 3 nanocrystalline zeolite suspensions [40] while the second has the capability of handling complex nonexponetial decays without a priori knowledge of their shapes.…”

Two‐Dye Core/Shell Zeolite Nanoparticles: A New Tool for Ratiometric pH Measurements

“…[26] In this respect, combining the possibility to synthesize nanosized zeolite particles with the optical properties of such dye-doped systems may offer new perspectives in developing multifunctional nanomaterials for biological applications. While a few papers have described the preparation of luminescent zeolite nanoparticles, [27][28][29] only one has shown their potential use as fluorescent biolabel. [30] In previous papers, we described the preparation of fluorescent zeolite nanoparticles involving 3-hydroxyflavone (3HF) as the guest dye and the zeolite b as the host matrix.…”