Covalent organic framework isomers and isomerism related applications

Isomerism offers a powerful paradigm for generating materials with distinct physicochemical properties from identical molecular compositions. The precise design of isomeric structures is therefore crucial for optimizing the performance of organic materials. This review focuses on the rational structural design of isomeric covalent organic frameworks (COFs), with the aim of elucidating how structural isomerism governs their properties. We scrutinize the design and synthetic strategies for representative COF isomers reported to date, including linkage adjustment, control of reaction conditions, the transformation of isomeric monomers into frameworks, and molecular configuration matching, to disclose rational design principles for isomeric COFs. The distinct performance of these COF isomers applied in selective absorption, photocatalysis, sensors, and so forth is summarized and compared, revealing key structure-property correlations. Finally, we conclude with an analysis of the advantages and constraints of isomeric COFs and outline key fundamental challenges deserving future research.