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Ammonia as Proton Conducting Medium Confined in Porous Materials

submitted on 24.11.2018, 06:15 and posted on 26.11.2018, 15:39 by Dae-Woon Lim, Hiromu Tsukada, Akihito Shigematsu, Teppei Yamada, Kazuya Otsubo, Alexander E. Khudozhitkov, Alexander G. Stepanov, Daniil I. Kolokolov, Mitsuhiko Maesato, Hiroshi Kitagawa

Molecular confinement within a limited space induces unique behaviour not seen in bulk systems. In particular, the proton diffusion in conducting medium under confined conditions is significantly affected by the surrounding environment.H2O, efficient conducting medium, confined in hydrophobic channels forms unique clusters allowing rapid diffusion, whereas confined NH3, having a similar degenerate system (Fig. 1a), has not been reported. Herein, we show NH3-mediated proton conduction in microporous metal–organic frameworks (MOFs), MIL-53(Al) functionalized with (-COOH)2, -NH2, -OH and -H. Anhydrous NH3 gas is trapped in the pore by proton donation of frameworks and forms hydrogen bonding networks exhibiting a remarkably enhanced proton conductivity. The crystallographic analysis and solid-state NMR clarify the veiled proton diffusion mechanism and unique dynamic behaviour of confined NH3.


The ACCEL program, Japan Science and Technology Agency (JST), JPMJAC1501.

Daniil I. Kolokolov, Alexander G. Stepanov, and Alexander E. Khudozhitkov acknowledge the support from budget project No. АААА-А17-117041710084-2 of the Boreskov Institute of Catalysis.


Email Address of Submitting Author


Kyoto University



ORCID For Submitting Author


Declaration of Conflict of Interest

No conflict of interest

Version Notes

This is version 1