sp-Hybridized carbon as a building block in the synthesis of molecules and materials

介绍。该提案概述了合成路线，以sp-杂化碳为关键构建块，具有明确的结构富碳分子。这些分子被设计用来回答化学、物理和材料科学中的基础和应用问题。该计划遵循“物理有机化学”方法：我们检查化学结构和分子反应性/性质之间的详细关系，通常通过热分析，电化学方法，x射线晶体学，以及核磁共振，发射和吸收光谱（EPR，振动和瞬态吸收光谱通过协作使用）。通常，我们的分子被设计用来回答合作者提出的特定问题，例如分子电子学和太阳能捕获。拟议的研究计划依赖于四个相互关联的主题。* * * 1。乙炔基结构。我们将开发新的策略，以合成共轭多炔作为功能材料，并模拟碳炔（sp-杂化碳构成的碳同素异形体）的性质。作为高能分子，多炔是特别具有挑战性的目标，我们将探索新的稳定方案来应对这些挑战。超分子策略是一个特定的焦点，通过合成轮烷。旋转是一个关键的设计主题，因为它允许在聚乙烯的末端功能化，例如，将分子线连接到电极或形成供体-受体聚乙烯。* * * 2。基于积雨团的构造。[n] culculene （n是累积双键的数目）为理解碳炔的性质提供了另一种结构。[n]积云的许多化学、电子和光学性质目前尚不清楚，我们打算回答有关积云中键的重要问题，如旋转势垒和键长交替。cumulene也将被用作反应前体，通过一种新的拓扑化学聚合反应形成富碳结构和聚合物。* * * 3。分子导线。探索和优化累积烯和多聚烯作为分子导线的功能。选择端基是为了方便与电极（如金和石墨烯）结合。该项目明显受益于聚炔和聚丙烯腈作为轮烷的稳定性（第1部分和第2部分），它们模拟绝缘分子线。* * * 4。合成碳同素异形体：图（二）炔结构。由sp-和sp2杂化碳（石墨炔和石墨炔）组成的碳同素异形体在溶液态合成是困难的，因为在聚合过程中缺乏选择性。我们将使用基于三乙基甲醇（TEtM）衍生的新构建模块的模板化方法。在炔和醇的“离去基”末端，可以很容易地改变TEtMs，以优化与金属的结合和反应性。

Introduction. This proposal outlines synthetic routes to carbon-rich molecules with defined structure using sp-hybridized carbon as a key building block. These molecules are designed to give answers to both fundamental and applied questions in chemistry, as well as physics and materials science. This program follows a “physical organic chemistry” approach: We examine detailed relationships between chemical structure and molecular reactivity/properties, commonly via thermal analyses, electrochemical methods, X-ray crystallography, as well as NMR, emission, and absorption spectroscopies (EPR, vibrational, and transient absorption spectroscopies are used via collaboration). Often, our molecules are designed to answer specific questions posed by collaborators in, for example, molecular electronics and solar energy capture. The proposed research program relies on four interrelated themes. ***1. Acetylene based structures. We will develop new strategies for the synthesis of conjugated polyynes to serve as functional materials and to model the properties of carbyne (the carbon allotrope constructed of sp-hybridized carbon). As high-energy molecules, polyynes are particularly challenging targets, and we will explore new stabilization schemes to meet these challenges. Supramolecular strategies are a specific focus, through synthesis of rotaxanes. Rotaxination is a key design motif, since it allows functionalization at the ends of a polyyne, e.g., for attaching molecular wires to electrodes or forming donor-acceptor polyynes. ***2. Cumulene based structures. [n]Cumulenes (n is the number of cumulated double bonds) provide an alternative structure toward understanding the properties of carbyne. Many chemical, electronic, and optical properties for [n]cumulenes are currently unknown, and we intend to answer seminal questions concerning bonding in cumulenes, such as rotational barriers and bond length alternation. Cumulenes will also be used as reactive precursors to form carbon-rich architectures and polymers via a new topochemical polymerization reaction. ***3. Molecular wires. We will explore and optimize cumulenes and polyynes to function as molecular wires. Endgroups are chosen to facilitate binding to electrodes such as gold and graphene. This project benefits distinctly from stabilization of polyynes and cumulenes as rotaxanes (Parts 1 and 2), which mimic insulated molecular wires. ***4. Synthetic carbon allotropes: Graph(di)yne structures. The solution-state synthesis carbon allotropes composed of sp- and sp2-hybridized carbon (graphyne and graphdiyne), is difficult due to a lack of selectivity during polymerization. We will use a templated approach based on new building blocks derived from triethynylmethanol (TEtM). TEtMs can be easily varied at the termini of the alkynes and the alcohol “leaving group” toward optimizing binding and reactivity on metals.