Topology-Controlled Proton Transport in Thermotropic Liquid-Crystalline Acid–Base Complexes

IF 7.1 2区材料科学 Q2 CHEMISTRY, PHYSICAL

Chemistry of Materials Pub Date : 2026-10-13 Epub Date: 2026-09-21 DOI:10.1021/acs.chemmater.6c01661

Chengyang Liu, Masafumi Yoshio

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Abstract

The construction of efficient proton-transport channels is of great interest for applications in fuel cells and biological systems. In particular, three-dimensionally interconnected bicontinuous networks in liquid-crystalline (LC) assemblies provide an attractive platform for enabling efficient proton transport. However, the realization of anhydrous proton-conducting gyroid cubic LC assemblies remains a significant challenge. Here we report a strategy to control the dimensionality and connectivity of proton-transport pathways through Brønsted base-acid complexation. A series of wedge-shaped amphiphiles bearing a common imidazole/amide headgroup and varying alkyl-chain lengths (IM8, IM10, and IM12) were complexed with two Brønsted acids with distinct anion characteristics, benzenesulfonic acid (BS) and bis(trifluoromethanesulfonyl)imide (HTFSI). Systematic variation of acid fraction and temperature under nonhumidified conditions revealed that IM12 exhibits curvature-driven polymorphism, including a hexagonal columnar (Col_h) phase at low acid fractions and a bicontinuous Ia3̅d gyroid (Gyr) phase at intermediate acid contents, whereas IM8 and IM10 form only smectic A (SmA) phases over broad compositions. ¹H NMR titration indicates that imidazole protonation and ion-pair formation dominate the base–acid equilibrium, while weaker secondary interactions involve the amide group. Variable-temperature FT-IR measurements reveal progressive strengthening of the polar interaction network upon cooling. Proton-transport measurements show that the Gyr base–acid complexes exhibit the highest conductivity, the lowest apparent activation energy, and weaker viscosity–conductivity coupling in Walden-type analysis. Dielectric modulus and rheological measurements further support faster bulk relaxation and a more robust elastic framework in the gyroid phase. These findings establish design principles for proton-conducting LC materials based on curvature-controlled, three-dimensionally interconnected ionophilic nanochannels formed through base–acid complexation.

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热致液晶酸碱配合物中拓扑控制的质子输运

高效质子传输通道的构建对燃料电池和生物系统的应用具有重要意义。特别是，液晶（LC）组件中的三维互连双连续网络为实现有效的质子传输提供了一个有吸引力的平台。然而，实现无水质子传导的陀螺立方LC组件仍然是一个重大的挑战。在这里，我们报告了一种通过Brønsted碱-酸络合控制质子传输途径的维度和连通性的策略。将一系列楔形两亲化合物（IM8、IM10和IM12）与两种具有不同阴离子特征的Brønsted酸——苯磺酸（BS）和双（三氟甲磺酰基）亚胺（HTFSI）进行络合。在非湿化条件下，IM12表现出曲率驱动的多晶性，在低酸组分下为六方柱状（Colh）相，在中等酸含量下为双连续的Ia3 -d旋形（Gyr）相，而IM8和IM10在大组分下仅形成近晶a （SmA）相。1H NMR滴定表明，咪唑质子化和离子对形成主导了酸碱平衡，而酰胺基则参与了较弱的二级相互作用。变温傅里叶变换红外测量显示极性相互作用网络在冷却后逐渐加强。质子输运测量表明，在瓦尔登型分析中，Gyr碱酸配合物的电导率最高，表观活化能最低，粘导耦合较弱。介电模量和流变测量进一步支持更快的体松弛和更强大的弹性框架在旋转阶段。这些发现建立了基于曲率控制的、通过酸碱络合形成的三维互连的亲离子纳米通道的质子导电LC材料的设计原则。

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来源期刊

Chemistry of Materials 工程技术-材料科学：综合

CiteScore

14.10

自引率

5.80%

发文量

929

审稿时长

1.5 months

期刊介绍： The journal Chemistry of Materials focuses on publishing original research at the intersection of materials science and chemistry. The studies published in the journal involve chemistry as a prominent component and explore topics such as the design, synthesis, characterization, processing, understanding, and application of functional or potentially functional materials. The journal covers various areas of interest, including inorganic and organic solid-state chemistry, nanomaterials, biomaterials, thin films and polymers, and composite/hybrid materials. The journal particularly seeks papers that highlight the creation or development of innovative materials with novel optical, electrical, magnetic, catalytic, or mechanical properties. It is essential that manuscripts on these topics have a primary focus on the chemistry of materials and represent a significant advancement compared to prior research. Before external reviews are sought, submitted manuscripts undergo a review process by a minimum of two editors to ensure their appropriateness for the journal and the presence of sufficient evidence of a significant advance that will be of broad interest to the materials chemistry community.