A Binuclear Zn(II) Complex Giving A Large Fluorescent Response Upon Binding PPi Anion.

A binuclear Zn(II)-Zn(II) complex 2b-Zn from a macrocyclic ligand 2b has been shown to be stable in an aqueous solution, exhibiting absorption (λ ≈ 367 nm) and weak blue fluorescence (λ ≈ 424 nm). The weak fluorescence intensity of the zinc complex could be dramatically increased when the solution was cooled. Upon addition of pyrophosphate ion (PPi), the resulting product gave a large bathochromic shift in both absorption (Δλ by ~ 57 nm) and fluorescence (Δλ by ~ 106 nm). Spectroscopic studies indicated that the resulting emissive species could be aggregation of the macrocyclic ligand that was accompanied with partial hydrolysis of imine bonds.