A bright red-emitting flavonoid for Al3+ detection in live cells without quenching ICT fluorescence

A bright red-emitting flavonoid derivative was synthesized, which exhibited a large Stokes shift (Delta lambda > 150 nm) and high fluorescence quantum yields (phi(fl) = 0.10-0.35). The probe could form a stable complex with Al3+ in 1 : 1 binding stoichiometry, generating a large bathochromic shift in both absorption and fluorescence (Delta lambda approximate to 70 nm) to enable ratiometric determination of cellular Al3+.