Ion polarisation-assisted hydrogen-bonded ferroelectrics in liquid crystalline domains

An alkylamide-substituted (-NHCOC₁₀H₂₁) hydrogen-bonded dibenzo[18]crown-6 derivative (1) was prepared to stabilise the ionic channel structure in a discotic hexagonal columnar (Col_h) liquid crystal. The introduction of simple M⁺X^- salts such as Na⁺PF₆ ^- and K⁺I^- into the ionic channel of 1 enhanced the ionic conductivity of the Col_h phase of the M⁺·(1)·X^- salts, with the highest ionic conductivity reaching ∼10^-6 S cm^-1 for K⁺·(1)·I^- and Na⁺·(1)·PF₆ ^- at 460 K, which was approximately 5 orders of magnitude higher than that of 1. The introduction of non-ferroelectric 1 into the ferroelectric N,N',N''-tri(tetradecyl)-1,3,5-benzenetricarboxamide (3BC) elicited a ferroelectric response from the mixed Col_h phase of (3BC) (1)_1- with x = 0.9 and 0.8. The further doping of M⁺X^- into the ferroelectric Col_h phase of (3BC)_0.9(1)_0.1 enhanced the ferroelectric polarisation assisted by ion displacement in the half-filled ionic channel for the vacant dibenzo[18]crown-6 of (3BC)_0.9[(M⁺)_0.5·(1)·(X^-)_0.5]_0.1.