%0 Journal Article %A Hoffman, Alexander E. J. %A Vanduyfhuys, Louis %A Nevjestić, Irena %A Wieme, Jelle %A Rogge, Sven M. J. %A Depauw, Hannes %A Van Der Voort, Pascal %A Vrielinck, Henk %A Speybroeck, Veronique Van %D 2018 %T Elucidating the Vibrational Fingerprint of the Flexible Metal–Organic Framework MIL-53(Al) Using a Combined Experimental/Computational Approach %U https://acs.figshare.com/articles/journal_contribution/Elucidating_the_Vibrational_Fingerprint_of_the_Flexible_Metal_Organic_Framework_MIL-53_Al_Using_a_Combined_Experimental_Computational_Approach/5818287 %R 10.1021/acs.jpcc.7b11031.s001 %2 https://acs.figshare.com/ndownloader/files/10291359 %K MIL %K dynamic %K vibrational %K mode %K simulation %K DFT %K Raman spectra show %K large-pore phases %K IR %X In this work, mid-infrared (mid-IR), far-IR, and Raman spectra are presented for the distinct (meta)­stable phases of the flexible metal–organic framework MIL-53­(Al). Static density functional theory (DFT) simulations are performed, allowing for the identification of all IR-active modes, which is unprecedented in the low-frequency region. A unique vibrational fingerprint is revealed, resulting from aluminum-oxide backbone stretching modes, which can be used to clearly distinguish the IR spectra of the closed- and large-pore phases. Furthermore, molecular dynamics simulations based on a DFT description of the potential energy surface enable determination of the theoretical Raman spectrum of the closed- and large-pore phases for the first time. An excellent correspondence between theory and experiment is observed. Both the low-frequency IR and Raman spectra show major differences in vibrational modes between the closed- and large-pore phases, indicating changes in lattice dynamics between the two structures. In addition, several collective modes related to the breathing mechanism in MIL-53­(Al) are identified. In particular, we rationalize the importance of the trampoline-like motion of the linker for the phase transition. %I ACS Publications