Artículo
Shedding Light on the Dark Corners of Metal-Organic Framework Thin Films: Growth and Structural Stability of ZIF-8 Layers Probed by Optical Waveguide Spectroscopy
Allegretto, Juan Alejandro
; Dostalek, Jakub; Rafti, Matias
; Menges, Bernhard; Azzaroni, Omar
; Knoll, Wolfgang
Fecha de publicación:
11/2018
Editorial:
American Chemical Society
Revista:
Journal of Physical Chemistry A
ISSN:
1089-5639
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
Metal-organic framework (MOF) thin films are promising materials for multiple technological applications, such as chemical sensing. However, one potential limitation for their widespread use in different settings is their stability in aqueous environments. In the case of ZIF-8 (zeolitic imidazolate framework) thin films, their stability in aqueous media is currently a matter of debate. Here, we show that optical waveguide spectroscopy (OWS), in combination with surface plasmon resonance (SPR) spectroscopy, offers a convenient way for answering intriguing questions related to the stability of MOF thin films in aqueous solutions and, eventually provide a tool for assessing changes in MOF layers under different environmental conditions. Our experiments relied on the use of ZIF-8 thin films grown on surface-modified gold substrates, as optical waveguides. We have found a linear thickness increase after each growing cycle and observed that the growing characteristics are strongly influenced by the nature of the primer layer. One of our findings is that substrate surface modification with a 3-mercapto-1-propanesulfonate (MPSA) primer layer is critical to achieve ZIF-8 layers that can effectively act as optical waveguides. We observed that ZIF-8 films are structurally stable upon exposure to pure water and 50 mM NaCl solutions but they exhibit a slight swelling and an increase in porosity probably due to the permeation of the solvent in the intergrain mesoporous cavities. However, OWS revealed that exposure of ZIF-8 thin films to phosphate-buffered saline solutions (pH 8) promotes significant film degradation. This poses an important question as to the prospective use of ZIF-8 materials in biologically relevant applications. In addition, it was demonstrated that postsynthetic polyelectrolyte modification of ZIF-8 films has no detrimental effects on the structural stability of the films.
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Articulos(INIFTA)
Articulos de INST.DE INV.FISICOQUIMICAS TEORICAS Y APLIC.
Articulos de INST.DE INV.FISICOQUIMICAS TEORICAS Y APLIC.
Citación
Allegretto, Juan Alejandro; Dostalek, Jakub; Rafti, Matias; Menges, Bernhard; Azzaroni, Omar; et al.; Shedding Light on the Dark Corners of Metal-Organic Framework Thin Films: Growth and Structural Stability of ZIF-8 Layers Probed by Optical Waveguide Spectroscopy; American Chemical Society; Journal of Physical Chemistry A; 123; 5; 11-2018; 1100-1109
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