A polynuclear Cu(ii) complex for real time monitoring of mitochondrial cytochrome C release during cellular apoptosis.

A new amide–imine conjugate, 2-hydroxybenzoic acid-(2-hydroxybenzylidene)-hydrazide (L1), is employed to prepare a single crystal X-ray structurally characterized poly-nuclear Cu(II) complex (M1). M1 selectively and spatially interacts with cytochrome C (Cyt C) to allow fluorescence imaging of intracellular translocation events in living cells. Thus, direct visualization of a Cyt C translocation event during an apoptotic process is achieved for the first time. The binding constant and LOD are 7.52 × 104 M−1 and 34.0 nM, respectively.