UiO-66 is a benchmark metal–organic framework that holds great promise for the design of new functional materials. In this work, we perform two-dimensional infrared measurements on polycrystalline membranes of UiO-66 grown on c-sapphire substrates. We study the symmetric and antisymmetric stretch vibrations of the carboxylate groups of the terephthalate linker ions and find that these vibrations show a rapid energy exchange and a collective vibrational relaxation with a time constant of 1.3 ps. We also find that the symmetric vibration of the carboxylate group is strongly coupled to a vibration of the aromatic ring of the terephthalate ion. We observe that the antisymmetric carboxylate vibrations of different terephthalate linkers show rapid resonant (Förster) energy transfer with a time constant of ∼1 ps.

The Netherlands Organisation for Scientific Research (NWO) , European Research Council (ERC)
J. Phys. Chem. Lett.
Ultrafast Spectroscopy

Korotkevich, A., Sofronov, O., Lugier, O., Sengupta, S., Tanase, S., & Bakker, H. (2022). Direct Probing of Vibrational Interactions in UiO-66 Polycrystalline Membranes with Femtosecond Two-Dimensional Infrared Spectroscopy. J. Phys. Chem. Lett., 13(42), 9793–9800. doi:10.1021/acs.jpclett.2c02509