Giant Crystalline Molecular Rotors that Operate in the Solid State |
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| Authors: | Rempei Ando Dr Ayana Sato-Tomita ProfDr Hajime Ito ProfDr Mingoo Jin |
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| Institution: | 1. Division of Applied Chemistry, Graduate School of Engineering, and Frontier Chemistry Center (FCC), Department of Engineering, Hokkaido University, Sapporo, Hokkaido, 060-8628 Japan;2. Division of Biophysics, Department of Physiology, Jichi Medical University, Shimotsuke-shi, Tochigi-ken, 329-0498 Japan;3. Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Hokkaido, 060-8628 Japan |
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| Abstract: | Molecular motion in the solid state is typically precluded by the highly dense environment, and only molecules with a limited range of sizes show such dynamics. Here, we demonstrate the solid-state rotational motion of two giant molecules, i.e., triptycene and pentiptycene, by encapsulating a bulky N-heterocyclic carbene (NHC) Au(I) complex in the crystalline media. To date, triptycene is the largest molecule (surface area: 245 Å2; volume: 219 Å3) for which rotation has been reported in the solid state, with the largest rotational diameter among reported solid-state molecular rotors (9.5 Å). However, the pentiptycene rotator that is the subject of this study (surface area: 392 Å2; volume: 361 Å3; rotational diameter: 13.0 Å) surpasses this record. Single-crystal X-ray diffraction analyses of both the developed rotors revealed that these possess sufficient free volume around the rotator. The molecular motion in the solid state was confirmed using variable-temperature solid-state 2H spin-echo NMR studies. The triptycene rotor exhibited three-fold rotation, while temperature-dependent changes of the rotational angle were observed for the pentiptycene rotor. |
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| Keywords: | Crystalline Materials Gold Complex Molecular Rotors N-Heterocyclic Carbenes |
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