Sensing, Imaging, Tuning and Creating Nanomaterial Chirality using Liquid Crystal Phases

手征性是一个中心的科学概念，最好的描述是不能通过平移和旋转将物体镜像到其镜像上。 最常见的例子是我们的左手和右手。 另一个展示手性概念的例子是香菜种子和留兰香中的活性成分。 虽然它们具有相同的分子结构，但这两种物质的味道不同，因为它们是手性对立面。 在纳米级（比人类头发的厚度小一千倍以上）创建和理解手性，对于在光学设备中使用材料，设计自然界中没有发现的材料（超材料），表征大型复杂生物分子以及制造新型传感器至关重要。 为了理解这种手性纳米材料，需要检测，测量，可视化和转移纳米手性。 在该项目中，由材料研究部门的固态和材料化学计划支持，研究团队使用液晶（通常用于LCD）来实现这些目标并找到它们的应用。 学生将体验到一个跨学科的研究导向的环境，利用国家的最先进的设备，并成为在展示他们的研究同行精通。 学生还通过旅行监督和与欧洲同事合作来体验合作研究。 该项目的特点是开展了几项外联活动，包括科学研讨会和对低收入家庭高中生的培训、为高中生和本科生举办的动手讲座和实验室研究。虚拟现实还将用于探索和可视化手性纳米材料。摘要金属纳米粒子或其原子表面可以通过金属基电子跃迁中的光学活性表现出手性。 这种手性可以通过手性有机分子的吸附或通过在手性环境中组装其他非手性或外消旋纳米颗粒来实现。 手性从吸附分子转移到金属纳米颗粒表面取决于吸附物的结构及其与周围环境的相互作用。这通常很难解释，因此是本项目的重点。 这项研究的动机是推进最近的发现，即纳米级的手性能够在软凝聚态系统（如液晶）中产生比有机分子手性对应物更强烈的响应。 该研究小组利用几种液晶相和材料作为理想成分来检测，可视化和调整纳米颗粒的手性。 为了测量，调整和可视化纳米级手性并应用手性纳米材料的全部潜力，研究小组专注于合成，表征和测试大小和形状不同的手性基序功能化金属纳米颗粒，以及用有效手性分子的自组装单层功能化的纳米级金属图案。 该研究也为纳米手性诱导和手性从各种液晶超结构转移到非手性和外消旋纳米粒子提供了新的前景。 相反，稳定性和诱导的旋光性也将在新发现的扭曲-弯曲双折射阶段进行检查。 结合起来，这些手性纳米材料作为可行的测试平台，从手性纳米传感器和可调手性超材料的应用，手性纳米诱导剂，鉴别剂和催化剂。

Non-technical AbstractChirality is a central scientific concept, and best described by the inability to superimpose an object onto its mirror image by translation and rotation. The most common example is our left and right hands. Another example to demonstrate the concept of chirality is the active ingredients in caraway seeds and spearmint. While they have identical molecular structures, the two substances taste differently because they are chiral opposites. Creating and understanding chirality at the nanoscale (more than thousand times smaller than the thickness of a human hair), is critical for the use of materials in optical devices, to engineer materials not found in nature (metamaterials), for the characterization of large, complex biomolecules and to make novel sensors. To understand such chiral nanoscale materials one needs to detect, measure, visualize, and transfer nanoscale chirality. In this project, supported by the Solid State and Materials Chemistry Program in the Division of Materials Research, the research team uses liquid crystals (commonly used in LCDs) to achieve these goals and to find their applications. Students will experience an interdisciplinary research-oriented environment, utilize state-of-the-art equipment, and become proficient in presenting their research to peers. Students also experience collaborative research by travelling oversees and working with colleagues in Europe. The project features several outreach activities including a scientific symposium and training of high school students from low-income households, hands-on lectures and lab research for high school and undergraduate students. Virtual reality will be also used to explore and visualize chiral nanomaterials. Technical AbstractMetal nanoparticles, or their atomic surfaces, can exhibit chirality by virtue of optical activity in metal-based electronic transitions. This chirality can be realized either by adsorption of chiral organic molecules, or by assembly of otherwise achiral or racemic nanoparticles in chiral environments. Transfer of chirality from an adsorbed molecule to a metal nanoparticle surface depends on the structure of the adsorbate and its interactions with the surrounding. This is often difficult to elucidate, and thus is the key focus of this project. The motivation for this research is to advance recent findings that chirality at the nanoscale is uniquely able to generate more intense responses in soft condensed matter systems such as liquid crystals than their organic molecular chiral counterparts. The research team utilizes several liquid crystal phases and materials as ideal constituents to detect, visualize, and tune chirality of nanoscale particles. To measure, tune, and visualize nanoscale chirality and apply the full potential of chiral nanomaterials, the research team focuses on the synthesis, characterization, and testing of chiral motif-functionalized metal nanoparticles differing in size and shape, and on nanoscale metal patterns functionalized with self-assembled monolayers of potent chiral molecules. The research also offers new prospects in nanoscale chiral induction and chirality transfer from various liquid crystal superstructures to achiral and racemic nanoparticles. Conversely, stabilization and induced optical activity will also be examined in the newly discovered twist-bend nematic phase. Combined, these chiral nanoscale materials serve as viable test platforms for applications ranging from chiral nanoscale sensors and tunable chiral metamaterials to chiral nanoscale inducers, discriminators, and catalysts.