Organotin-Oxo Clusters with Enhanced π-Conjugation for Iodine Capture

The sustainable development of nuclear energy raises significant challenges in handling radioactive iodine (I₂). Tin-oxo clusters are multimetal aggregates composed of Sn-oxide motifs and surface ligands. Sn^2/4+ ions have a strong affinity for iodine, making tin-oxo clusters promising candidates for trapping I₂. In this work, we constructed two BINOL (=1,1′-binaphthol)-based organotin-oxo clusters with bowl-shaped structures and used them in iodine absorption study. The BINOL-based organotin-oxo clusters demonstrated remarkable performance in an I₂ vapor adsorption experiment, with Sn₆L₄ achieving an adsorption capacity of 1.36 g·g^–1 at 80 °C. Combining experimental characterizations and theoretical calculations, we found that the BINOL-based organotin-oxo clusters interact with iodine through charge transfer interactions and Sn–I bondings. Additionally, the introduction of a butyl group enhances the adsorption capacity by facilitating C–H–I interactions. The research paves the way for the development of tin-oxo cluster-based iodine adsorbents.