CO delivery molecule 1 (compound 4) exhibits subcellular localization in the endoplasmic reticulum, mitochondria, and lysosomes. Such localization leads to the manifestation of CO-induced toxicity effects. Notably, the anti-inflammatory properties of CO delivery molecule 1, quantified through TNF-α suppression, are evident at nanomolar concentrations even without CO release. Furthermore, visible-light-induced CO release further enhances its anti-inflammatory effects [1].