Le Phuong H, Zasada Leo B, Xiao Dianne J
Department of Chemistry, University of Washington, Seattle, Washington 98195, United States.
Acc Chem Res. 2025 Jun 3;58(11):1776-1785. doi: 10.1021/acs.accounts.5c00171. Epub 2025 May 19.
ConspectusIn this Accounts article, we summarize our recent work on truncating conjugated two-dimensional framework materials down to a single pore, or a single macrocycle. Conjugated 2D architectures have emerged as one of the most synthetically adaptable motifs for coupling semiconductivity and porosity in metal-organic frameworks (MOFs) and covalent organic frameworks (COFs). However, despite their prevalence, 2D architectures have several limitations. In particular, the strong interlayer π-π stacking can limit both processability and the accessibility of internal active sites. We have found that simple macrocycles preserve key aspects of 2D framework structure and function, including porosity and out-of-plane electrical conductivity, while providing improved processability, surface tunability, and mass transport properties. In this article, we first describe our synthetic approach and general design considerations. Specifically, we show how ditopic analogues of the tritopic ligands commonly found in the synthesis of 2D MOFs and COFs can be used to achieve a diverse library of conjugated macrocycles that resemble fragments of semiconducting frameworks in both form and function. The length of the peripheral side chains, the size of the aromatic core, and the solubility of intermediates are all key variables in favoring selective macrocycle formation over undesired linear polymers and oligomers. Next, we highlight the unique advantages that macrocycles provide, including improved processability, atomically precise surface tunability, and greater active site accessibility. In particular, the identity of the peripheral side chains dramatically impacts both solubility and colloidal stability as well as crystal size and morphology. We further show how the solution processability and nanoscale dimensions of macrocycles can simplify electronic device fabrication and improve electrochemical performance. Finally, we end with a forward-looking discussion on how macrocycles offer a unique bridge between conjugated molecules and extended frameworks, enabling new application areas and fundamental science.
概述
在这篇综述文章中，我们总结了我们最近关于将共轭二维框架材料截短至单个孔或单个大环的工作。共轭二维结构已成为金属有机框架（MOF）和共价有机框架（COF）中用于耦合半导体性和孔隙率的最具合成适应性的基序之一。然而，尽管它们很普遍，但二维结构有几个局限性。特别是，强烈的层间π-π堆积会限制加工性和内部活性位点的可及性。我们发现简单的大环保留了二维框架结构和功能的关键方面，包括孔隙率和面外电导率，同时提供了改进的加工性、表面可调性和传质性能。在本文中，我们首先描述我们的合成方法和一般设计考虑因素。具体来说，我们展示了在二维MOF和COF合成中常见的三齿配体的双齿类似物如何用于实现各种共轭大环库，这些大环在形式和功能上类似于半导体框架的片段。外围侧链的长度、芳环核心的大小以及中间体的溶解度都是有利于选择性形成大环而不是不期望的线性聚合物和低聚物的关键变量。接下来，我们强调大环提供的独特优势，包括改进的加工性、原子精确的表面可调性和更大的活性位点可及性。特别是，外围侧链的性质对溶解度、胶体稳定性以及晶体尺寸和形态都有显著影响。我们进一步展示了大环的溶液加工性和纳米级尺寸如何简化电子器件制造并改善电化学性能。最后，我们以前瞻性讨论作为结尾，探讨大环如何在共轭分子和扩展框架之间提供独特的桥梁，从而实现新的应用领域和基础科学。
