Iodine-induced conductivity enhancement via polyiodide formation in a copper(I) MOF

Abstract

The development of materials that can simultaneously capture radioactive iodine and translate iodine uptake into a measurable electronic response is of significant interest. In this study, we demonstrate the reversible iodine adsorption of a copper(I) metal-organic framework ( Cu-MOF ) having Cu4I4 secondary building units. Upon exposure to iodine vapour, the Cu-MOF achieves an iodine uptake of ≈1.8 g g–1. The iodine adsorption directly alters the electronic and optical properties of the framework. The Cu-MOF also exhibited a reversible optical response to iodine vapour. In addition, iodine incorporation induces a 3.3 × 103 orders-of-magnitude enhancement in electrical conductivity through halogen-bond-driven charge transfer involving Cu4I4 units and π-conjugated ligands. Spectroscopic analyses confirm the in situ formation of electronically active polyiodide species, accompanied by band-gap narrowing. This work demonstrates halogen-bond-stabilised polyiodide formation as a strategy for coupling iodine capture with electronic functionality, with implications for optical iodine sensing and remediation-related electronic applications. © 2026 Elsevier B.V.