CAREER: Liquid Crystal-Templated Sequential Infiltration Synthesis of Hybrid Organic/Inorganic Materials with Multidimensional Chiral Structures

手性是分子或结构的一种几何性质，它不能与镜像相匹配。它在DNA、蛋白质和甲虫壳等自然系统中广泛存在。它在手性机械和光学结构、生物分离、制药等领域也具有重要意义。目前对手性结构的探索主要涉及低机械强度有机材料的分子设计和自组装。然而，工程应用所需的具有优异性能的有机/无机杂化材料在合成这些材料方面受到重大知识空白的困扰。在美国国家科学基金会材料研究部的固态与材料化学项目和凝聚态物理项目的支持下，首席研究员和她在北德克萨斯大学的研究小组通过使用丰富的手性液晶（CLCs）作为这些混合有机/无机材料的成核和生长的模板，研究了开发手性杂化材料的新策略。这是一个综合的教育研究计划，以化学反应，物理行为和结构工程的基本理解为中心，涉及将LC形态转化为混合或完全无机材料；并揭示潜在的结构-性质关系，以解锁手性赋予的多维结构，以及潜在的新型光学和机械特性。该项目促进软物质科学和工程领域的STEM教育，特别强调女性和西班牙裔学生的参与。通过创造夏季研究机会，研讨会和外展活动，首席研究员努力包括，激励和授权来自代表性不足的群体的学生，激发他们对材料科学的兴趣和参与。这些活动是专门为培养新一代的科学家和工程师而设计的，他们能更好地反映达拉斯-沃斯堡地区的多样性，并在北德克萨斯州及其他地区建立一个全国认可的软物质项目。技术摘要：液晶中的手性向列相或胆甾相表现出分子的不对称排列，从而导致相邻分子之间的有限扭转角和类似DNA中的螺旋超结构的远程手性有序。手性的增加导致了三维立方对称的形成，被称为蓝相（bp），它由双扭曲的圆柱体组成。lc的手性（从纳米到微米）广泛应用于显示技术、电光和传感器。然而，要充分利用这些有益的手性结构的潜力来适应不同的工程条件，例如温度、应力和化学环境，需要克服LCs固有的机械弱性质。特别是，快速增长的小型化器件技术市场要求材料具有集成的灵活性和微/纳米级精度的光学和机械性能，所有这些都使clc比传统的固体晶体材料处于更独特的地位。在这个CAREER项目中，由NSF材料研究部固态与材料化学项目和凝聚态物理项目支持，首席研究员和她的研究小组研究了2D/3D手性模板促进的新型反应机制，以合成具有不同长度尺度手性的混合有机/无机材料。用于LC结构聚合的介生单体中的官能团极性基团作为顺序渗透合成金属氧化物的反应基团。由高手性LCs（包括bp）形成的螺旋层次和三维晶格结构，引导了模板内有机金属前体的扩散、成核和生长。通过将先进的实验技术与计算模型相结合，本研究推进了对CLCs中无机物质的热力学、输运和位点选择性的基本认识。此外，首席研究员还研究了复杂多维CLC/BP结构中有机/无机物种的分子结构、协同自组装和空间控制成核和生长之间的相互作用。这种基本的理解允许合理设计手性结构金属氧化物增强LC复合材料，并释放其在不同应用领域的全部潜力，包括手性光学，手性机械设备，不对称催化，手性分离和传感器。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL ABSTRACTChirality is a geometric property of a molecule or structure that cannot be made to match its mirror image. It is widely prevalent in natural systems like DNA, proteins, and beetle shells. It is also of vital importance in diverse fields such as chiral mechanical and optical structures, bioseparation, and pharmaceuticals. Current exploration of chiral structures mostly involves molecular design and self-assembly of low mechanical strength organic materials. However, the kind of hybrid organic/inorganic materials with superior properties required for engineering applications are plagued by significant knowledge gaps in terms of synthesizing these materials. With this CAREER award, supported by the Solid State and Materials Chemistry program and the Condensed Matter Physics program, both in NSF’s Division of Materials Research, the principal investigator and her research group at the University of North Texas investigate new strategies for developing chiral hybrid materials by using abundant chiral liquid crystals (CLCs) as templates for nucleation and growth of these hybrid organic/inorganic materials. This is an integrated education-research program that centers on a fundamental understanding of the chemical reactions, physical behavior, and structural engineering involved in transforming LC morphologies into hybrid or fully inorganic materials; and revealing underlying structure-property relationships to unlock chirality-endowed multidimensional structures, as well as potentially novel optical and mechanical properties. The project promotes STEM education in soft-matter science and engineering, with a particular emphasis on engaging female and Hispanic students. By creating summer research opportunities, workshops and outreach activities, the principal investigator strives to include, inspire, and empower students from underrepresented groups, kindling their interests and participation in materials science. Activities are specifically designed to educate a new generation of scientists and engineers who better reflect the diversity of the Dallas-Fort Worth area, and to build a nationally-recognized soft-matter program in North Texas and beyond. TECHNICAL ABSTRACTChiral nematic or cholesteric phases in liquid crystals (LCs) exhibit asymmetrical packing of molecules, and thereby result in a finite twist angle between adjacent molecules and long-range chiral ordering similar to helical superstructures in DNA. The increase in chirality leads to the formation of 3D cubic symmetry, known as blue phases (BPs), that consist of double-twisted cylinders. The chiral properties of LCs (from nano to micrometers) are widely used in display technologies, electro-optics, and sensors. However, exploiting the full potential of such beneficial chiral structures to adapt to diverse engineering conditions, e.g., temperature, stress, and chemical environments, needs to overcome the inherently mechanically weak nature of LCs. In particular, the rapidly growing market for miniaturized device technologies requires materials with integrated flexibility and optical and mechanical performance at micro/nanoscale precision, all of which put CLCs in a more unique position than conventional solid crystalline materials. In this CAREER project, supported by the Solid State and Materials Chemistry program and the Condensed Matter Physics program, both in NSF’s Division of Materials Research, the principal investigator and her research group study novel reaction mechanisms facilitated by 2D/3D chiral templates to synthesize hybrid organic/inorganic materials with chirality across disparate length scales. The functional polar groups in mesogenic monomers used for LC structure polymerization serve as reactive moieties for sequential infiltration synthesis of metal oxides. The helical hierarchical and 3D lattice structures formed by highly chiral LCs, including BPs, guide the diffusion, nucleation, and growth of organometallic precursors inside the templates. By combining advanced experimental techniques and computational modeling, the research advances the fundamental understanding of thermodynamics, transport, and site selectivity of inorganic species in CLCs. Furthermore, the principal investigator studies the interplay among molecular architecture, synergistic self-assembly, and spatially controlled nucleation and growth of organic/inorganic species within complex multidimensional CLC/BP structures. This fundamental understanding allows the rational design of chiral-structured metal oxide-reinforced LC composites and unlocks their full potential in diverse application fields that include chiral optics, chiral mechanical devices, asymmetric catalysis, chiral separation and sensorsThis award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.