LAUSR

Covalent organic frameworks, cross-linked crystalline polymers constructed from rigid organic precursors connected by covalent interactions, have emerged as a promising class of nanoporous materials owing to their highly desirable combination of attributes, including facile chemical tunability, structural diversity, and excellent stability. Despite the distinct advantages offered by three-dimensional covalent organic frameworks, research efforts have predominantly focused on the more synthetically-accessible, two-dimensional variants. Here we present an overview of synthetic approaches to yield three-dimensional covalent organic frameworks, identify synthetic obstacles that have hindered progress in the field and recently-employed methods to address them, and propose alternative techniques to circumvent these synthetic challenges.Three-dimensional covalent organic frameworks are attractive functional materials, although there are fewer examples than their two-dimensional counterparts. Here, the authors review the synthetic approaches yielding these compounds, and highlight key challenges facing researchers in the field.