Direct Probing of Vibrational Interactions in UiO-66 Polycrystalline Membranes with Femtosecond Two-Dimensional Infrared Spectroscopy

Abstract

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.

Synergy of Ligands in Tailoring the Photocatalytic Properties of Zirconium Metal–Organic Framework-Impregnated Membranes for Water Treatment

“…The diffraction peaks appearing at 7.3° and 8.7° represent the (1 1 1) and (2 0 0) crystal planes corresponding to the face-centered cubic structure of Zr-MOFs. These peaks are retained in the XRD pattern of MOF-PSF membrane along with a broad peak that appeared at 2θ ∼ 18.1°, denoting the XRD peak corresponding to the polysulfone (PSF) membrane …”