Water‐Induced Single‐Crystal to Single‐Crystal Transformation of Ionic Hydrogen‐Bonded Organic Frameworks with Enhanced Proton Conductivity

Abstract

AbstractTwo ionic hydrogen‐bonded organic frameworks (iHOF‐10, iHOF‐11) were prepared using 1,1′‐diamino‐4,4′‐bipyridine diiodide (Dbpy ⋅ 2I) and tetrakis(4‐sulfophenyl)ethylene (H4TPE). With increasing RH and temperature, water molecules induce single crystal to single crystal (SCSC) transformation of iHOF‐10, resulting in the formation of iHOF‐11. At 90 °C, 98 % RH, the proton conductivity of iHOF‐11 (7.03×10−3 S cm−1) is 2.09 times higher than iHOF‐10 (3.37×10−3 S cm−1). At 50 °C, 98 % RH, iHOF‐11 (9.49×10−4 S cm−1) is 19.06 times higher than iHOF‐10 (4.98×10−5 S cm−1). The proton conductivity shows water molecules enter the crystal and induce crystal transformation and reorganization of the hydrogen bonding structure, thus increasing the proton conductivity and stability.