Molecular Accessibility and Diffusion of Resorufin in Zeolite Crystals
Abstract
We have used confocal laser scanning microscopy on the small, fluorescent resorufin dye molecule to visualize molecular accessibility and diffusion in the hierarchical, anisotropic pore structure of large (~10 μm‐sized) zeolite‐β crystals. The resorufin dye is widely used in life and materials science, but only in its deprotonated form because the protonated molecule is barely fluorescent in aqueous solution. In this work, we show that protonated resorufin is in fact strongly fluorescent when confined within zeolite micropores, thus enabling fluorescence microimaging experiments. We find that J‐aggregation guest–guest interactions lead to a decrease in the measured fluorescence intensity that can be prevented by using non‐fluorescent spacer molecules. We characterized the pore space by introducing resorufin from the outside solution and following its diffusion into zeolite‐β crystals. The eventual homogeneous distribution of resorufin molecules throughout the zeolite indicates a fully accessible pore network. This enables the quantification of the diffusion coefficient in the straight pores of zeolite‐β without the need for complex analysis, and we found a value of 3×10−15 m2 s−1. Furthermore, we saw that diffusion through the straight pores of zeolite‐β is impeded when crossing the boundaries between zeolite subunits.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 09, 2023
- Source ID
- 10.1002/chem.202302553
Entities
People
- Alfons van Blaaderen
- Bert Weckhuysen
- Florian Meirer
- Freddy T Rabouw
- J J Erik Maris
- Katarina Stanciakova
- Koen M. H. Berendsen
- Luke A. Parker
- Nikolaos Nikolopoulos
Organizations
- Army Research Office
- Dutch Research Council
- ETH Zurich
- Netherlands Organisation for Applied Scientific Research
- Utrecht University