A reversible calix[4]arene armed phenolphthalein based fluorescent probe for the detection of Zn and an application in living cells.

A reversible and easy assembled fluorescent sensor based on calix[4]arene and phenolphthalein (C4P) was developed for selective zinc ion (Zn ) sensing in aqueous samples. The probe C4P demonstrated high selective and sensitive detection towards Zn over other competitive metal ions. Interaction of Zn with a solution of C4P resulted in a considerable increment in emission intensity at 440 nm (λ  = 365 nm) due to the suppression of photoinduced electron transfer (PET) process and the restriction of C=N isomerization. The binding constant (K ) of C4P with Zn was calculated to be 4.50 × 10  M and also the limit of detection of C4P for Zn was as low as 0.108 μM (at 10  M level). Moreover, the fluorescence imaging in the human colon cancer cells suggested that C4P had great potential to be used to examine Zn in vivo.