LEAPS-MPS: Mobility and reactivity of covalent organic framework precursors under physical confinement by exfoliated 2D materials

该奖项全部或部分根据2021年美国救援计划法案（公法117-2）资助。非技术摘要共价有机框架（COF）是结晶二维聚合物的一个不同领域，由于组分之间键合的几何形状和反应物分子上存在的键和官能团的性质的可变性，其具有高度可调的性质。 COF的形成“约束下”已被研究在各种接口，但不是两个固体表面之间的反应物被困。 石墨烯是共价连接的碳原子的单层，其容易从石墨剥离并且可以在固体表面捕获高度移动的分子。 通过这个LEAPS-MPS项目，克拉克森大学的Ryan Brown教授的研究小组研究了石墨烯和固体表面之间的捕获反应物，以研究固-固界面处的COF形成。 他们研究了当反应物被限制在固体界面之间时COF生长的变化。 由于竞争反应或高温下的解吸，一些COF键不容易通过在表面或溶液中的直接缩合反应形成。 Brown教授的研究小组采用石墨烯限制作为进行这些不可接近的反应的策略，以及使用石墨烯捕获来图案化COF生长，用于通常不通过直接缩合反应形成的连接。 除了科学方面，该项目还通过为终身教职员工举办研讨会邀请，为来自代表性不足背景的本科生举办专业发展研讨会，并为当地土著社区的高中生提供有偿研究经验。技术摘要二维共价有机框架（COFs）的生长限制在各种界面是一个活跃的领域，根据限制的性质，它会产生各种结果。 然而，到目前为止，该领域中的现有工作主体没有解决在由固-固界面限制下形成2D-COF的后果。 了解COF生长限制在固-固界面之间是重要的，用于评估采用这类材料作为插层物种的可行性，以修改二维材料，如过渡金属二硫属化物和MXene的化学，光学或电学性质。 通过这个LEAPS-MPS项目，Ryan Brown教授的研究小组探索了固体表面之间的物理限制对COF生长的影响，采用扫描探针显微镜（SPM），空间分辨傅里叶变换红外光谱（FTIR）和密度泛函理论计算来评估剥离的石墨烯和固体界面之间限制的COF前体的流动性和反应性的变化。 剥离的石墨烯可以将气体、液体和小分子限制在固体界面处，并且石墨烯-云母和石墨烯-Au（111）界面被用作实验上可访问的模型系统以用于在固-固界面处的限制。 Brown教授的研究小组研究了石墨烯覆盖层对COFs生长和形态的影响，COFs是由单一和多种反应物体系的常见缩合反应形成的。 这项工作还延伸到评估在表面使用石墨烯限制以产生通过直接缩合反应不容易获得的COF连接的可行性。 此外，布朗教授与克拉克森大学现有的组织合作，通过一系列丰富的活动和研究机会，加强指导，培训和职业发展的本科生和终身教职员工从数学和物理科学的代表性不足的背景。 来自北方纽约原住民社区的高中生也通过这个项目获得了宝贵的研究机会和经验。这个奖项反映了NSF的法定使命，并被认为值得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来支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Non-Technical AbstractCovalent organic frameworks (COFs) are a diverse field of crystalline two-dimensional polymers that have highly tunable properties due to the geometry of the bonding between components and variability in the nature of the bond and functional groups present on the reactant molecules. The formation of COFs “under confinement” has been studied at a variety of interfaces, but not for reactants trapped between two solid surfaces. Graphene is a single layer of covalently linked carbon atoms that is easily exfoliated from graphite and can trap highly mobile molecules at solid surfaces. With this LEAPS-MPS project, Professor Ryan Brown’s research group at Clarkson University investigates trapping reactants between graphene and a solid surface to study COF formation at a solid-solid interface. They look at how COF growth changes when reactants are confined between solid interfaces. Some COF linkages are not easily formed through a direct condensation reaction at surfaces or in solution due to competing reactions or desorption at the high-temperatures. Prof. Brown’s group employes graphene confinement as a strategy for carrying out these inaccessible reactions, as well as using graphene trapping to pattern COF growth for linkages not normally formed through direct condensation reactions. In addition to the science aspects, the project also engages underrepresented communities within the Mathematical and Physical sciences field through seminar invitations for pre-tenure faculty, professional development workshops for undergraduate students from underrepresented backgrounds, and the provision of paid research experience for high school students from the local indigenous communities.Technical AbstractThe growth of two-dimensional covalent organic frameworks (COFs) confined at a variety of interfaces is an active field with a variety of outcomes based on the nature of the confinement. So far though, the existing body of work in this field does not address the consequences of forming 2D-COFs under confinement by a solid-solid interface. Understanding COF growth confined between solid-solid interfaces is important for assessing the viability of employing this class of materials as intercalation species to modify the chemical, optical, or electrical properties of two-dimensional materials such as transition metal dichalcogenides and MXenes. With this LEAPS-MPS project, Professor Ryan Brown’s research group explores the impact of physical confinement between solid surface on COF growth by employing scanning probe microscopy (SPM), spatially-resolved Fourier transform infrared spectroscopy (FTIR), and density functional theory calculations to assess changes in the mobility and reactivity of COF precursors confined between exfoliated graphene and solid interfaces. Exfoliated graphene can confine gases, liquids, and small molecules at solid interfaces, and the graphene-mica and graphene-Au(111) interfaces are used as experimentally accessible model systems for confinement at a solid-solid interface. Professor Brown’s research group investigates the impact of a graphene capping layer on the growth and morphology of COFs formed from common condensation reactions for single and multiple reactant systems. This work also extends to assessing the viability of using graphene confinement at surfaces to produce COF linkages not readily accessible through direct condensation reactions. Additionally, Professor Brown works with existing organizations within Clarkson University to enhance the mentoring, training, and career progression undergraduate students and pre-tenure faculty members from underrepresented backgrounds in Mathematical and Physical Sciences through a series of enrichment activities and research opportunities. High school students from the northern New York indigenous communities gain valuable research exposure and experience through this program, as well.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.