Proton Conduction at High Temperature in High‐Symmetry Hydrogen‐Bonded Molecular Crystals of RuIII Complexes with Six Imidazole‐Imidazolate Ligands. Issue 47 (26th July 2022)

• Record Type: Journal Article
• Authors: Tadokoro, Makoto; Itoh, Masaki; Nishimura, Ryota; Sekiguchi, Kensuke; Hoshino, Norihisa; Kamebuchi, Hajime; Miyazaki, Jun; Kobayashi, Fumiya; Mizuno, Motohiro; Akutagawa, Tomoyuki
• Is Part Of: Chemistry. Volume 28:Issue 47(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-07-26
• Subjects: cubic structures -- hydrogen bonds -- imidazole complexes -- Pourbaix diagram -- proton transport; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202201397
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: A new H‐bonded crystal [Ru III (Him)3 (Im)3 ] with three imidazole (Him) and three imidazolate (Im − ) groups was prepared to obtain a higher‐temperature proton conductor than a Nafion membrane with water driving. The crystal is constructed by complementary N−H⋅⋅⋅N H‐bonds between the Ru III complexes and has a rare Icy‐c* cubic network topology with a twofold interpenetration without crystal anisotropy. The crystals show a proton conductivity of 3.08×10 −5 S cm −1 at 450 K and a faster conductivity than those formed by only HIms. The high proton conductivity is attributed to not only molecular rotations and hopping motions of HIm frameworks that are activated at ∼113 K, but also isotropic whole‐molecule rotation of [Ru III (Him)3 (Im)3 ] at temperatures greater than 420 K. The latter rotation was confirmed by solid‐state 2 H NMR spectroscopy; probable proton conduction routes were predicted and theoretically considered. Abstract : A new H‐bonded crystal of [Ru III (Him)3 (Im)3 ](1 ) with six HIm (imidazole) was prepared so as to obtain a high‐temperature proton conductor. The crystal is constructed through N−H⋅⋅⋅N−H‐bonds between the inter‐Ru III complexes and has a rare Icy‐c* cubic net without crystal anisotropy. The proton conductivity is due not only to rotations and hopping motions of HIm, but also induced by isotropic whole‐molecule rotation of 1 .