Direct Visualization of Chemically Resolved Multilayered Domains in Mixed-Linker Metal–Organic Frameworks

Published

June 15, 2023

Author(s)

Andrea Centrone, Belén Lerma-Berlanga, Adam Biacchi, Carmen Fernández Conde, Georges Pavlidis, Carlos Martí-Gastaldo

Abstract

The modular synthesis approach for assembling inorganic nodes and organic multidentate linkers into reticular solids enables rational engineering in porous materials known as metal-organic frameworks (MOFs). Incorporation of two or more linker types in MOF crystals is an emerging paradigm for engineering their pores to achieve complex functionalities, by virtue of chemically heterogeneous domains. However, this strategy is challenged by the insufficient spatial resolution of conventional, chemically sensitive techniques that hinders the verification of rational design. Here we leverage the high spatial resolution and chemical specificity of infrared nanoscopy in combination with high-throughput diffraction-limited hyperspectral photoluminescence imaging to determine the composition of individual crystals of linker-exchanged UiO-68 mixMOF. Contrary to previous assumptions, the MOF crystals consist of a 3-layer onion-like structure composed ofa UiO-68 core, an intermediate mixMOF layer with a gradient in linker composition and an external shell that consist mainly of hydrogen-bonded linker molecules, rather than a crystalline MOF. Since this outer layer is also found in prototypical UiO-68 MOFs and it is insoluble, we speculate that it consists of a protoMOFs which precedes the formation of the MOF crystalline phase. This study advances our analytical capabilities for studying and engineering heterogeneous domains in mixMOF individual crystals down to the nanoscale.

Citation

Advanced Functional Materials

Volume

33

Issue

41

Pub Type

Journals

Download Paper

https://doi.org/10.1002/adfm.202302357

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Keywords

Metal-Organic Frameworks, multivariate MOF, photothermal induced resonance (PTIR), AFM-IR, nanoscale IR spectroscopy.

Citation

Centrone, A. , Lerma-Berlanga, B. , Biacchi, A. , Fernández Conde, C. , Pavlidis, G. and Martí-Gastaldo, C. (2023), Direct Visualization of Chemically Resolved Multilayered Domains in Mixed-Linker Metal–Organic Frameworks, Advanced Functional Materials, [online], https://doi.org/10.1002/adfm.202302357, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=936294 (Accessed October 21, 2025)