Musozoda Muhammadiqboli, O'Brien Richard A, Metott Zachary J, Jerdo Raychell A, Butch Christopher M, Zeller Matthias, Boyce Gregory R, Hillesheim Patrick C, Mirjafari Arsalan
Department of Chemistry, State University of New York at Oswego, Oswego, New York 13126, United States.
Department of Chemistry, The University of South Alabama, Mobile, Alabama 36688, United States.
ACS Mater Au. 2025 Jul 21;5(5):878-885. doi: 10.1021/acsmaterialsau.5c00089. eCollection 2025 Sep 10.
Bacteria employ cyclopropane motifs as bioisosteres for unsaturations to modulate lipid bilayer fluidity and protect cellular membranes under environmental stress. Drawing inspiration from this biological strategy, we investigated how cyclopropanation impacts the thermophysical properties of lipid-inspired ionic liquids. We synthesized a series of imidazolium-based ionic liquids incorporating cyclopropanated derivatives of three renewable terpenoids: phytol, farnesol, and geraniol. Through an integrated approach combining property-driven design, thermophysical analysis, X-ray crystallography, and computational modeling, we systematically examined how these structural modifications influence quantitative structure-property relationships. Our findings demonstrate that ionic liquids with long alkyl appendages respond to side-chain modificationsparticularly the synergistic combination of cyclopropanation and branchingin a manner that mimics homeoviscous adaptation in living organisms. The strategic incorporation of cyclopropyl moieties combined with chiral methyl branching produced dramatic melting point depressions, with phytol-derived ionic liquids achieving the lowest melting points reported to date for these bioinspired materials. This effectiveness results from positioning these structural elements within the symmetry-breaking region of alkyl chains, where they maximally disrupt molecular packing and enhance fluidity. X-ray crystallographic analysis of a cyclopropanated citronellyl-based ionic liquid revealed that the cyclopropyl ring induces significant conformational distortions that prevent efficient molecular organization. The use of terpenoids from the chiral pool as starting materials imparts inherent sustainability to these ILs. Enantiopure ILs can be synthesized from renewable feedstocks like phytol and citronellol while exploiting bioinspired structural design principles. This work provides new insights into IL structure-property relationships that both complement and extend previous discoveries, establishing a framework for the rational design of lipidic ionic liquid systems with enhanced fluidity and chemical stability from renewable resources.
细菌利用环丙烷基序作为不饱和键的生物电子等排体，以调节脂质双层流动性，并在环境压力下保护细胞膜。受这一生物学策略的启发，我们研究了环丙烷化如何影响脂质类离子液体的热物理性质。我们合成了一系列基于咪唑鎓的离子液体，其中包含三种可再生萜类化合物（叶绿醇、法尼醇和香叶醇）的环丙烷化衍生物。通过结合性质驱动设计、热物理分析、X射线晶体学和计算建模的综合方法，我们系统地研究了这些结构修饰如何影响定量构效关系。我们的研究结果表明，具有长烷基支链的离子液体对侧链修饰（特别是环丙烷化和支化的协同组合）的响应方式类似于生物体中的同型粘性适应。环丙基部分与手性甲基支化的策略性结合产生了显著的熔点降低，叶绿醇衍生的离子液体达到了这些仿生材料迄今为止报道的最低熔点。这种有效性源于将这些结构元素定位在烷基链的对称破坏区域内，在那里它们最大限度地破坏分子堆积并增强流动性。对一种环丙烷化香茅基离子液体的X射线晶体学分析表明，环丙基环会引起显著的构象扭曲，从而阻止有效的分子组织。使用手性库中的萜类化合物作为起始原料赋予了这些离子液体内在的可持续性。对映体纯的离子液体可以从叶绿醇和香茅醇等可再生原料合成，同时利用仿生结构设计原则。这项工作为离子液体的构效关系提供了新的见解，既补充又扩展了以前的发现，建立了一个合理设计具有增强流动性和化学稳定性的脂质离子液体系统的框架，这些系统来自可再生资源。
