Erik Maris J J, Parker Luke A, Stanciakova Katarina, Nikolopoulos Nikolaos, Berendsen Koen M H, van Blaaderen Alfons, Meirer Florian, Rabouw Freddy T, Weckhuysen Bert M
Inorganic Chemistry and Catalysis Group, Utrecht University, Debye Institute for Nanomaterials Science and, Institute for Sustainable and Circular Chemistry, Universiteitsweg 99, 3584 CG, Utrecht (The, Netherlands.
Optical Materials Engineering Laboratory, ETH Zürich, Leonhardstrasse 21, 8092, Zürich, Switzerland.
Chemistry. 2024 Jan 2;30(1):e202302553. doi: 10.1002/chem.202302553. Epub 2023 Nov 9.
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 m s . Furthermore, we saw that diffusion through the straight pores of zeolite-β is impeded when crossing the boundaries between zeolite subunits.
我们利用共聚焦激光扫描显微镜对小的荧光试卤灵染料分子进行研究，以观察其在大型（约10μm大小）β沸石晶体的分级各向异性孔结构中的分子可达性和扩散情况。试卤灵染料在生命科学和材料科学中广泛应用，但仅以其去质子化形式使用，因为质子化分子在水溶液中几乎不发荧光。在这项工作中，我们表明质子化的试卤灵在限制于沸石微孔内时实际上具有很强的荧光，从而能够进行荧光显微成像实验。我们发现J-聚集客体-客体相互作用导致测量的荧光强度降低，而使用非荧光间隔分子可以防止这种情况。我们通过从外部溶液引入试卤灵并跟踪其扩散到β沸石晶体中来表征孔空间。试卤灵分子最终在整个沸石中均匀分布，这表明存在一个完全可及的孔网络。这使得无需复杂分析就能对β沸石直孔中的扩散系数进行量化，我们得到的值为3×10⁻¹⁰ m² s⁻¹。此外，我们还发现，当穿过沸石亚基之间的边界时，通过β沸石直孔的扩散会受到阻碍。
