A Phosphate-Based Silver–Bipyridine 1D Coordination Polymer with Crystallized Phosphoric Acid as Superprotonic Conductor |
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Authors: | Arun Pal Shyam Chand Pal Prof Kazuya Otsubo Prof Dae-Woon Lim Santanu Chand Prof Hiroshi Kitagawa Dr Madhab C Das |
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Institution: | 1. Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, WB, 721302 India;2. Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502 Japan |
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Abstract: | Phosphate-based silver–bipyridine (Ag-bpy) 1D coordination polymer {{Ag(4,4′-bpy)}2{Ag(4,4′-bpy)(H2PO4)}] ⋅ 2 H2PO4 ⋅ H3PO4 ⋅ 5 H2O}n ( 1 ) with free phosphoric acid (H3PO4), its conjugate base (H2PO4−) and water molecules in its lattice was synthesized by room-temperature crystallization and the hydrothermal method. An XRD study showed that coordinated H2PO4−, lattice H2PO4− anions, free H3PO4 and lattice water molecules are interconnected by H-bonding interactions, forming an infinitely extended 2D H-bonded network that facilitates proton transfer. This material exhibits a high proton conductivity of 3.3×10−3 S cm−1 at 80 °C and 95 % relative humidity (RH). Furthermore, synthesis of this material from commercially available starting materials in water can be easily scaled up, and it is highly stable under extreme conditions of conductivity measurements. This report inaugurates the usage and design principle of proton-conducting frameworks based on crystallized phosphoric acid and phosphate. |
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Keywords: | conducting materials coordination polymers hydrogen bonds proton conduction proton transport |
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