Probing Zeolite Crystal Architecture and Structural Imperfections using Differently Sized Fluorescent Organic Probe Molecules

Frank C. Hendriks, Joel E. Schmidt, Jeroen A. Rombouts, Koop Lammertsma, Pieter C.A. Bruijnincx, Bert M. Weckhuysen*

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


A micro-spectroscopic method has been developed to probe the accessibility of zeolite crystals using a series of fluorescent 4-(4-diethylaminostyryl)-1-methylpyridinium iodide (DAMPI) probes of increasing molecular size. Staining large zeolite crystals with MFI (ZSM-5) topology and subsequent mapping of the resulting fluorescence using confocal fluorescence microscopy reveal differences in structural integrity: the 90° intergrowth sections of MFI crystals are prone to develop structural imperfections, which act as entrance routes for the probes into the zeolite crystal. Polarization-dependent measurements provide evidence for the probe molecule's alignment within the MFI zeolite pore system. The developed method was extended to BEA (Beta) crystals, showing that the previously observed hourglass pattern is a general feature of BEA crystals with this morphology. Furthermore, the probes can accurately identify at which crystal faces of BEA straight or sinusoidal pores open to the surface. The results show this method can spatially resolve the architecture-dependent internal pore structure of microporous materials, which is difficult to assess using other characterization techniques such as X-ray diffraction.

Original languageEnglish
Pages (from-to)6305-6314
Number of pages10
JournalChemistry - A European Journal
Issue number26
Publication statusPublished - 5 May 2017


The authors wish to thank Dr. Florian Meirer (Utrecht University, UU) for help with the data analysis. Dr. Javier Ruiz-Mart?nez (UU), Dr. Joost van der Lit (UU) and Dr. Zoran Ristanovi? (UU) are acknowledged for useful discussions, whereas ?zg?n Attila (UU) is acknowledged for providing the MFI crystal SEM images. This work is financially supported by a Top grant of CW-NWO. J.S. has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 702149. Dr. Machteld Mertens (ExxonMobil) and Prof. Mark E. Davis (California Institute of Technology) are acknowledged for providing the MFI and BEA crystals, respectively.

FundersFunder number
Horizon 2020 Framework Programme
H2020 Marie Skłodowska-Curie Actions702149
Horizon 2020
ExxonMobil Foundation


    • confocal fluorescence microscopy
    • crystal growth
    • fluorescent probes
    • polarization dependence
    • zeolites


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