International Research Fellowship Program: Helical Chirality Amplification through Constitutional Dynamic Chemistry

Folmer-Andersen国际研究奖学金计划使美国科学家和工程师能够在国外进行9到24个月的研究。 该计划的奖项提供了联合研究的机会，以及使用国外独特或互补的设施，专业知识和实验条件。该奖项将支持Frantz Folmer-Andersen博士与Jean-Marie P. Lehn博士在法国斯特拉斯堡的Louis Pasteur大学进行为期24个月的研究。生物系统随着越来越多的秩序和复杂性而进化，它存在于从分子到宏观的多个组织层次。在这个层次的根源在于信息编码的序列小（亚纳米）重复单元内的生物聚合物。 这种连续的信息通过非共价物理相互作用被处理多次，这可以被认为是插入算法，以提供精确折叠的生物机器。这种策略的应用程序的“自下而上”的合成定义良好的纳米和微观架构需要控制的结构信息的表达跨越大小尺度和层次。拟议的活动旨在通过设计程序化的单体，在纯合成系统内建立这种控制，这些单体含有以可预测的方式指导高阶低聚物折叠的结构特征。分子和低聚物结构之间的相互关系，然后将询问通过宪法动态化学（CDC），它依赖于可逆的交换组件作为一种手段，在低聚物组件内产生的多样性。具体而言，这项工作的目的是使用不对称单体产生手性偏见（首选扭转正义）在可逆连接的螺旋低聚物，然后通过CDC，影响优先纳入外源单体的外消旋混合物的一种对映异构体到偏见的低聚物。对映体选择的实验方法依赖于单体和螺旋超结构之间的非对映体相互作用。鉴于蛋白质和遗传物质的同手性和螺旋结构，这项工作所展示的手性扩增的一般过程反映了一个合理的进化机制。 此外，这种组分选择方法可以应用于动态纳米系统的一般设计。这样的材料将能够从可用的池中选择组分以构建规定的纳米级物体，并且响应于刺激，被诱导以解构物体并通过组分池的重组来构建不同的物体。这种自发但可控的分子机器组装和拆卸的实现可能会对纳米技术和材料科学领域产生重大影响。

0601296Folmer-AndersenThe International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four-month research fellowship by Dr. Frantz Folmer-Andersen to work with Dr. Jean-Marie P. Lehn at Universite Louis Pasteur in Strasbourg, France.Biological systems have evolved with increasing order and complexity, which exist throughout multiple organizational levels, from the molecular to the macroscopic. At the root of this hierarchy lies information encoded by sequences of small (sub-nanometer) repeat units within biopolymers. This sequential information is processed several times over through non-covalent physical interactions, which may be thought of as interactional algorithms, to afford precisely folded biological machinery. The application of this strategy to the "bottom-up" synthesis of well-defined nano- and microscopic architectures necessitates control over the expression of structural information across size scales and hierarchical levels. The proposed activities seek to establish such control within purely synthetic systems through the design of programmed monomers, which contain structural features that direct higher-order oligomer folding in a predictable way. The interrelationship between molecular and oligomer structure will then be interrogated by way of constitutional dynamic chemistry (CDC), which relies on the reversible interchange of components as a means of generating diversity within oligomeric assemblies. Specifically, this work aims to use asymmetric monomers to generate chiral bias (preferred twist-sense) in reversibly linked helical oligomers; and then through CDC, to affect the preferential incorporation of one enantiomer of a racemic mixture of exogenous monomers into the biased oligomers. The experimental approach to enantioselection relies on diastereomeric interactions between the monomers and the helical superstructure. In light of the homochirality and helical structures of proteins and genetic material, the general process of chirality amplification demonstrated by this work reflects a plausible evolutionary mechanism. Further, this method of component selection may be applied to the general design of dynamic nanosystems. Such materials would be capable of selecting components from an available pool to build up prescribed nanoscale objects, and in response to stimuli, be induced to deconstruct the objects and build different ones by recombination of the component pool. The achievement of this type of spontaneous but controlled assembly and disassembly of molecular machines could strongly impact the fields of nanotechnology and materials science.