Tailoring the Properties of Molecular Assemblies via Noncovalent Interactions

分子尺度的非共价相互作用普遍存在于生物、材料和化学体系中。虽然在个体层面上相对较弱，但当它们协同作用时，可以对分子结构和动力学产生强大的影响。氢键的影响是众所周知的，而一些卤素分子中类似的相互作用，称为卤素键，则研究得很少。卤素键合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。通过拟议的研究，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属性之间的联系的独特化学见解。这项工作具有重要意义，因为它将识别卤键供体和受体中的分子特征，这些分子特征控制着这些构建块组装成超分子结构，从而促进我们对什么决定材料性质的理解，并提供一条调控观察到的行为的化学路线。预测方法代表了一种全新的方法来考虑从下到上设计具有所需性质的超结构，使用非共价相互作用作为组装机制。卤键的可调性使得有可能在精细的水平上调整相互作用强度，从而允许对组装形成的额外控制。一旦实施了数据启用的优化程序，就可以为特定任务创建具有所需特性的组件，这将代表着功能材料设计的重大进步。此外，一般做法并不特定于某一特定财产，可适用于任何涉及类似捐赠者/接受者构件的应用。控制材料组装将实现巨大的新功能，并催化多个领域的变革性进步。在研究的同时，教学和外联活动将教育下一代科学家功能材料，并让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。这个项目解决了与定向组装相关的基础科学知识缺口，它与NSF支持基础研究的使命是一致的，与科学教育和社区外展紧密结合。这项提议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，其特征有助于更有效的化学和环境过程。据推测，调节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，使用分子级构建块来生成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，它非常适合于未来先进优化算法的集成。具体目标包括：(1)表征卤键给体和受体的分子性质，以确定几何结构、原子取代和官能化的影响；(2)评估稳定性，量化卤键强度，并确定给体/受体单元中非共价相互作用的性质；以及(3)指导具有定制结构、电子和光学性质的扩展的二维和三维卤键网络的组装。这些目标与定向组装具有所需特性的超分子结构的总体目标一致，同时解决了能够实现更有效的化学过程、改善环境可持续性和推进具有定制性能的功能材料的设计的研究。这些研究将为特定类别的供体/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，这项拟议的研究对化学、生物、物理和材料科学等许多科学领域具有重要的基础性意义和影响。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.