Covalent organic frameworks (COFs) are crystalline and porous materials with bi- or three-dimensional structures built up by connecting their molecular precursors by dynamic covalent bonds. Using bottom-up or top-down strategies, bi-dimensional COFs can be obtained as single- or few-layer materials, thus enlarging the family of 2D-materials based on graphene. The main advantage of 2D-materials based on COFs is the fact that they can be chemically designed, thus allowing the formation of á la carte materials with well-designed functionalities including their size and features of their pores. The aim of this perspective review is to illustrate in a rational way the current state-of-the-art in the field of COF nanosheet formation using the two general approaches of material nano-structuring. This article reviews a selected collection of samples that illustrates the essential concepts, strategies of preparation following the two general approaches, bottom-up and top-down, and a selection of COF nanolayers showing seminal properties and potential material applications. Finally, we provide some perspectives of this novel research field.

中文翻译：

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共价有机骨架纳米片：制备，性质和应用。

共价有机骨架（COF）是具有二维或三维结构的晶体和多孔材料，通过动态共价键连接它们的分子前体来建立。使用自下而上或自上而下的策略，可以将二维COF作为单层或几层材料获得，从而扩大了基于石墨烯的2D材料系列。基于COF的2D材料的主要优点是可以对它们进行化学设计，因此可以形成具有精心设计的功能（包括其大小和孔特征）的点菜材料。本观点综述的目的是使用两种材料纳米结构的一般方法，以合理的方式说明COF纳米片形成领域的最新技术。本文回顾了一些选定的样品，这些样品阐明了基本概念，遵循两种通用方法（自下而上和自上而下）的制备策略，以及精选的具有开创性和潜在材料应用的COF纳米层。最后，我们提供了这一新颖研究领域的一些观点。