Controlled Encapsulation of Functional Organic Molecules within Metal-Organic Frameworks: In Situ Crystalline Structure Transformation

Porous material cages bright molecules

23 June 2017

Metal-organic frameworks (MOFs) are highly porous materials formed from metal atoms linked by organic molecules, giving them a huge internal surface area that can store other molecules. Researchers at Nanjing Tech University have now developed an efficient strategy to increase the loading of functional molecules without impairing a MOF’s performance.

They first created a MOF called ZIF-L, based on zinc ions and linker molecules called imidazoles that assembled into flat, atom-thin sheets held together by weak hydrogen bonds. Then they added a fluorescent molecule, which became trapped between the layers. Finally, heating the MOF in a mixture of two solvents rearranged its internal structure to form a strong, three-dimensional cage that locked the fluorescent molecules in place.

This composite could act as a sensor for small molecules containing a halogen atom that can access the MOF’s pores and switch off the fluorescence within.

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References

1. Advanced Materials 29,1606290 (2017). doi: 10.1002/adma.201606290