Β-Cyclodextrin biomimetic Organoiridium triggered intracellular transfer hydrogenation cleavage and imaging

High active organometallic catalyst always faced neck in biological sensing due to poor biocompatibility and scarce catalytic triggered signal release reactions, although it has already demonstrated extremely high application potential in biological orthogonal catalytic fields. Here, we firstly showed a novel organoiridium catalyst Ir1@CD by assembling β - cyclodextrin (β-CD) and adamantane functionalized pyridine-amide iridium complexes Ir1 , which was characterized by Two-dimensional rotating-frame overhauser spectroscopy (2D ROSEY) 1 H NMR and Isothermal Titration Calorimetry ITC (bonding constant Ks ~10 5  M −1 ). Over 20.0 % yield increase was obtained when Ir1@CD was used as catalysts compared to Ir1 for trimethyl p-benzoquinone TMBQ hydrogenation, which demonstrated that β-CD could significantly enhanced catalytic activity of Ir1 . Further, a robust biomimetic catalytic hydrogen transfer sensing system was established by combining Ir1@CD with new stable quinone‑hydrogenation-cleavage probes PMNQ . The sensing system presented higher fluorescence enhancement factor (19.7-fold), good linear responses ranged from 1.56 to 50 μM, lower limits of detection LOD (160.0 nM) for cofactor NADH, and could be successfully applied in intracellular imaging of NADH. The provided biocatalytic strategy will also be expected to use in other fields, such as biomimetic organometallic catalysts, drug delivery and many more chemical-biological technologies.