title: Structural dynamics inside a functionalized metal-organic framework probed by ultrafast 2D IR spectroscopy.
abstract: The structural elasticity of metal-organic frameworks (MOFs) is a key property for their functionality. Here, we show that 2D IR spectroscopy with pulse-shaping techniques can probe the ultrafast structural fluctuations of MOFs. 2D IR data, obtained from a vibrational probe attached to the linkers of UiO-66 MOF in low concentration, revealed that the structural fluctuations have time constants of 7 and 670 ps with no solvent. Filling the MOF pores with dimethylformamide (DMF) slows the structural fluctuations by reducing the ability of the MOF to undergo deformations, and the dynamics of the DMF molecules are also greatly restricted. Methodology advances were required to remove the severe light scattering caused by the macroscopic-sized MOF particles, eliminate interfering oscillatory components from the 2D IR data, and address Förster vibrational excitation transfer.
authors.affiliation: Department of Chemistry, Stanford University, Stanford, CA 94305;
authors.forename: Jun
authors.initials: J
authors.lastname: Nishida
authors.affiliation: Department of Chemistry, Stanford University, Stanford, CA 94305;
authors.forename: Amr
authors.initials: A
authors.lastname: Tamimi
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego, CA 92093; and.
authors.forename: Honghan
authors.initials: H
authors.lastname: Fei
authors.affiliation: Department of Chemistry, Ångström Laboratory, Uppsala University, 75120 Uppsala, Sweden.
authors.forename: Sonja
authors.initials: S
authors.lastname: Pullen
authors.affiliation: Department of Chemistry, Ångström Laboratory, Uppsala University, 75120 Uppsala, Sweden.
authors.forename: Sascha
authors.initials: S
authors.lastname: Ott
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego, CA 92093; and scohen@ucsd.edu fayer@stanford.edu.
authors.forename: Seth M
authors.initials: SM
authors.lastname: Cohen
authors.affiliation: Department of Chemistry, Stanford University, Stanford, CA 94305; scohen@ucsd.edu fayer@stanford.edu.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Fayer
keywords: 2D IR spectroscopy; UiO-66 MOF; metal–organic framework; solvent confinement effect; ultrafast structural fluctuations