Tailoring the Properties of Molecular Assemblies via Noncovalent Interactions

分子尺度的非共价相互作用遍及生物、材料和化学系统。虽然在个体层面上相对较弱，但当它们协同作用时，它们可以对分子结构和动力学产生强烈的影响。氢键的作用是众所周知的，而在一些含卤素分子中类似的相互作用，称为卤素键，研究得很少。卤素键能在多大程度上指导具有特定材料特性的超分子结构的组装尚不确定。通过提出的研究，将开发一种新的建模范式，旨在提供关于分子水平和更大规模材料特性之间连接的独特化学见解。这项工作意义重大，因为它将识别控制这些构建块组装成超分子结构的卤素键供体和受体的分子特征，从而促进我们对决定材料特性的因素的理解，并提供一种化学途径来调节所观察到的行为。这种预测方法代表了一种全新的方式，可以使用非共价相互作用作为组装机制，自下而上地设计具有所需属性的上层结构。卤素键的可调性使得可以在精细的水平上调整相互作用强度，从而允许对组装形成进行额外的控制。一旦数据优化程序得以实施，就有可能为特定任务创建具有所需属性的组件，这将代表功能材料设计的重大进步。此外，一般方法并不特定于特定属性，可以适用于涉及类似供体/受体构建块的任何应用程序。控制材料组装将实现巨大的新功能，并催化许多领域的变革性进步。在研究的同时，教学和推广活动将教育下一代科学家关于功能材料的知识，并吸引不同的学生群体参与STEM主题，包括历史上代表性不足的群体和有学习障碍的群体。该项目解决了与定向装配相关的基础科学知识差距，它与NSF支持基础研究的使命相一致，与科学教育和社区外展紧密结合。本提案的总体目标是开发由卤素键和其他非共价相互作用结合的分子组装，具有促进更有效的化学和环境过程的特征。据推测，调整分子组分之间卤素键的强度和性质将能够指导组装形成并定制系统的结构，电子和光学性质。建模研究将指导自下而上的材料设计，使用分子水平的构建块来产生超分子结构并控制其功能。分子量子化学和原子模拟将被用来产生一种预测形式，这种形式非常适合未来集成先进的优化算法。具体目标包括：(1)表征卤素键供体和受体的分子性质，以确定几何形状、原子取代和功能化的影响；(2)评估稳定性，量化卤素键强度，并确定供体/受体单元中非共价相互作用的性质；(3)指导具有定制结构、电子和光学特性的扩展二维和三维卤素键合网络的组装。这些目标与具有所需特性的超分子结构定向组装的总体目标一致，同时解决研究，使更有效的化学过程，提高环境可持续性，并推进具有定制特性的功能材料的设计。这些研究将为某一类供体/受体网络提供预测能力；然而，定向组装的基本原理与其他材料和生物系统高度相关。因此，所提出的研究对化学、生物学、物理学和材料科学等许多科学领域都具有重要的基础意义和影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Molecular scale noncovalent interactions pervade biological, materials, and chemical systems. Although relatively weak on an individual level, they can have a strong impact on molecular structuring and dynamics when acting in concert. The effects of hydrogen bonding are well-known, while the analogous interaction in some halogen-containing molecules, termed halogen bonding, is far less studied. The extent that halogen bonding can direct the assembly of supramolecular structures with specific material characteristics is undetermined. Through the proposed studies, a new modeling paradigm will be developed that aims to provide unique chemical insight regarding the connectivity between the molecular-level and larger-scale material properties. This work is significant because it will identify molecular signatures in halogen bond donors and acceptors that control the assembly of these building blocks into supramolecular structures, thereby advancing our understanding of what dictates the material properties and providing a chemical route to modulate the observed behavior. The predictive approach represents an entirely new way to think about designing suprastructures with desired properties from the bottom up using noncovalent interactions as the assembly mechanism. The tunability of halogen bonds makes it possible to adjust the interaction strength on a fine level, allowing for additional control over assembly formation. Once the data-enabled optimization procedures are implemented, it will be possible to create assemblies with desired properties for particular tasks, which will represent a significant advance in functional materials design. Moreover, the general approach is not specific to a particular property and could be adapted for any application involving similar donor/acceptor building blocks. Controlling material assembly will enable vast new functionalities and catalyze transformative advances across a number of fields. Concurrent with the research, the teaching and outreach activities will educate the next generation of scientists on functional materials and engage a diverse student population on STEM topics, including historically underrepresented groups and those with learning disabilities. This project addresses the basic science knowledge gap associated with directed assembly, and it is consistent with the NSF mission of supporting fundamental research, tightly integrated with science education and community outreach.The overarching objective of this proposal is to develop molecular assemblies, bound by halogen bonds and other noncovalent interactions, with characteristics that facilitate more efficient chemical and environmental processes. It is hypothesized that tuning the strength and nature of halogen bonding between the molecular components will enable the ability to direct assembly formation and tailor the structural, electronic, and optical properties of the system. Modeling studies will guide bottom-up materials design using molecular-level building blocks to generate supramolecular structures and control their function. Molecular quantum chemistry and atomistic simulation will be used to produce a predictive formalism that is well suited for future integration of advanced optimization algorithms. Specific aims include the following: (1) Characterize the molecular properties of halogen bond donors and acceptors to ascertain the effects of geometry, atomic substitution, and functionalization; (2) Assess stability, quantify halogen bonding strength, and determine the nature of noncovalent interactions in donor/acceptor units; and (3) Direct the assembly of extended two- and three-dimensional halogen bonded networks with tailored structural, electronic, and optical properties. These aims align with the overarching objective of directed assembly of supramolecular structures with desired characteristics, while concurrently addressing research that enables more efficient chemical processes, improves environmental sustainability, and advances the design of functional materials with tailored properties. These studies will provide predictive capabilities for a particular class of donor/acceptor networks; however, the underlying principles of directed assembly are highly relevant to other materials and biological systems. Thus, the proposed research is of great fundamental importance and impactful to many scientific fields in chemistry, biology, physics, and materials science.This 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.