Nitric Oxide Encapsulation in Metal‐Organic Cages via Physical Confinement

Comprehensive Summary The stabilization of active molecules is significantly important for chemistry, especially for the bioactive molecules. In this work, we report the synthesis and characterization of three tetrahedral Fe 4 L 6 cages, which are water‐soluble and functionalized with or without PEG chains. All cages can physically trap NO molecules in their cavities to prevent a reaction with O 2 . Single‐crystal X‐ray diffraction (SCXRD), Griess assay, electron paramagnetic resonance (EPR) spectroscopy, and fluorescence assay demonstrate that NO molecules were encapsulated and stabilized by these cage molecules through the formation of host‐guest supramolecules. These NO‐loaded cages show high antibacterial activities for inhibiting Staphylococcus aureus and Escherichia coli , providing a convenient method for making antibiotic agents. Moreover, these PEG‐functionalized cages exhibit excellent biocompatibility, providing a new strategy for developing materials for NO delivery in biomedical applications