Smith, Jordan N.Ennis, CourtneyDoan, Huan V.Ting, Valeska P.White, Nicholas G.2026-06-112026-06-110947-6539https://hdl.handle.net/1885/733810298Despite their promise as porous supramolecular materials, permanently porous halogen-bonded frameworks have not been realized, and progress in the field is limited by a lack of understanding of what happens when these materials are activated via solvent exchange or under vacuum. In the current work, a single building block bearing complementary iodoalkyne halogen bond donors and pyridine-N-oxide acceptors is described. Crystallization is solvent dependent, with initial experiments giving networks containing unwanted hydrogen bonding interactions between components. Subsequent optimization of conditions enabled the generation of a 3D network assembled by only halogen bonds. Upon solvent exchange, the 3D network undergoes an unprecedented single-crystal transformation to a new 2D phase. Synchrotron far-infrared spectroscopy was employed to identify diagnostic signals for the phase transition. These results add to our understanding of the dynamic nature of halogen-bonded network materials.enPublisher Copyright: © 2026 The Author(s). Chemistry – A European Journal published by Wiley-VCH GmbH.crystal engineeringhalogen bondN-oxideporous networkself-recognition202610.1002/chem.71010105035906196