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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Poster 2

CPP 17.4: Poster

Dienstag, 6. September 2022, 11:00–13:00, P2

Dipolar Molecular Rotors in Surface-Anchored Metal Organic Frameworks — •Xianghui Zhang¹, Sebastian Hamer², Ritesh Haldar³, Daniel Reuter⁴, Florian Paneff¹, Dirk Volkmer⁴, Peter Lunkenheimer⁴, André Beyer¹, Ian Howard³, and Rainer Herges² — ¹Faculty of Physics, Bielefeld University, 33615 Bielefeld — ²Otto-Diels-Institute for Organic Chemistry, Christian-Albrechts-University of Kiel, 24098 Kiel — ³Karlsruhe Institute of Technology (KIT), 76344 Karlsruhe — ⁴Institute of Physics, Augsburg University, 86135 Augsburg, Germany

Molecular rotors arranged in the surface-anchored metal-organic frameworks (SURMOF) were investigated. The rotating part of each linker molecule consists of a fluorine-substituted phenyl group connected with acetylene linkages to the Cu clusters. Dielectric spectroscopy was used to investigate the rotation dynamics of molecular rotors in a parallel capacitor assembly. We determined an activation energy of 10 kJ/mol for one SURMOF type consisting of 3-[4-(2-carboxyethynyl)-2,3-difluoro-phenyl]prop-2-ynoic acid (C12H4F2O4) as dipolar linkers and 1,4-diazabicyclo(2.2.2)octane (DABCO) as pillars, at temperatures above 170 K. A smaller barrier of about 2 kJ/mol was found for the corresponding SURMOFs without any pillars. The analog made from the non-polar linker was used as a control system and showed no dielectric relaxation processes down to 20 K. The observed activation energy barriers are consistent with ab initio DFT modelling and classical dipole-dipole interaction calculations.