Ca-triazine phosphonate metal–organic framework as fungicide active packaging

Abstract

A novel three-dimensional metal–organic framework (MOF) based on the biocompatible/bioactive, earth-abundant calcium and the photoactive triazine triphosphonate ligand has been hydrothermally synthesised and fully characterised (XRD, FTIR, TGA, SEM, etc.). Denoted as IEF-32 (IEF stands for the IMDEA Energy Framework), its crystal structure was unveiled by single-crystal X-ray diffraction, exhibiting free P–OH groups in two coordination modes (–PO₃H₂ and –PO₃H) and acid unsaturated metal sites. This robust structure shows high thermal and chemical stability (in several catalytically-relevant organic solvents and water, pH = 3 to 12). Furthermore, this study presents the first proof of concept for employing a Ca phosphonate MOF as an antifungal and preservative agent in active packaging. Specifically, IEF-32 effectively preserved grapes, extending their shelf life to one month under fungal spoilage and ripening conditions (relative humidity 80%, 21 °C) while retaining its structural and chemical integrity. Finally, in vitro studies confirmed the biosafety of IEF-32 in intestinal and pulmonary cells, opening new avenues for the implementation of Ca-based P-MOFs in sustainable food preservation technologies.