Covalent-coordination driven hierarchical assembly of tubular frameworks

Abstract Hierarchical assembly, inspired by nature, is widely employed by chemists to construct complex materials using elementary building units, mainly depending on the non-covalent interactions owing to their dynamic binding nature 1–6 . Integrating covalent bonds into hierarchical assembly processes can impart anisotropic mechanical properties, but poses significant challenges. Here we present a covalent-coordination driven hierarchical assembly strategy to build highly crystalline tubular frameworks. A multilevel oriented organization assembly process driven by dynamic covalent, coordination, metal-ionic interactions of subcomponents is shown to be versatile, producing a supramolecular nanotubular framework (SNF) and three covalently-linked nanotubular frameworks (CNFs). These materials consist of well-ordered triangular nanotubes assembled in an oriented manner, with their atomic-resolution structures thoroughly characterised. In CNFs, the spacing between adjacent nanotubes can be systematically adjusted by altering the connector lengths to create mesoporous structures with adjustable pore size 7 . Moreover, reversible transformations between CNFs and two-dimensional (2D) covalent organic frameworks (COFs) 8–12 were achieved by the reversible addition and removal of Zn(NO 3 ) 2 . This study represents a significant advancement in hierarchical assembly, opening up new possibilities for the design and application of novel materials across diverse fields.