Polarity profiling of porous architectures: solvatochromic dye encapsulation in metal–organic frameworks
Heidi A. Schwartz, Murat Atar, Matthias Spilles, M. A. Fill, M. A. Ott, Felix R. S. Purtscher, Josef M. Gallmetzer, Baris Öcal, Selina Olthof, Axel G. Griesbeck, Klaus Meerholz, Thomas S. Hofer, Uwe Ruschewitz
Abstract
Metal-organic frameworks (MOFs) have gathered significant interest due to their tunable porosity leading to diverse potential applications. In this study, we investigate the incorporation of the fluorosolvatochromic dye 2-butyl-5,6-dimethoxyisoindoline-1,3-dione ([double bond, length as m-dash]Phth) into various MOF structures as a means to assess the polarity of these porous materials. As a purely inorganic compound, zeolite Y was tested for comparison. The fluorosolvatochromic behavior of Phth, which manifests as changes in its emission spectra in response to solvent polarity, provides a sensitive probe for characterizing the local environment within the MOF pores. Through systematic variation of the MOF frameworks, we demonstrate the feasibility of using (fluoro-)solvatochromic dyes as probes for assessing the polarity gradients within MOF structures. Additionally, the fluorosolvatochromic response was studied as a function of loading amount. Our findings not only offer insights into the interplay between MOF architecture and guest molecule interactions but also present a promising approach for the rational design and classification of porous materials based on their polarity properties.