Distinct photophysical behaviour and transport of cell-impermeable [Ru(bpy)2dppz]2+ in live cells using cucurbit[7]uril as a delivery system

Here, we report the delivery of a cell-impermeable [Ru(bpy)2dppz]2+ complex across a cell membrane using a cucurbit[7]uril molecular container. Encapsulation of complex 1 in the cucurbit[7]uril cavity showed an 830-fold enhancement in the luminescence intensity of the non-emissive complex in aqueous solution. This molecular light-switch effect stems from the incorporation of the dppz ligand of 1 inside the CB7 cavity and can be attributed to long range coulombic forces between Ru2+ and the carbonyl portal of CB7 via CH⋯O interactions. This is reflected in the 1H-NMR experiments, and further corroborated by theoretical calculations.