A pyrazoline-based fluorescent chemosensor for Al3+ ion detection and live cell imaging

Abstract

Two pyrene-appended pyrazoline compounds (PY-I and PY-II) were designed and synthesized. Their photophysical properties were studied by absorption and fluorescence spectral studies. PY-I displays an excellent selective and sensitive response to Al³⁺ ions over other metal ions, whereas PY-II did not respond to any metal ions. A 1 : 1 stoichiometry for the PY-I–Al³⁺ complex was observed with an association constant of 2.13 × 10³ M⁻¹. Furthermore, PY-I was employed for fluorescence imaging of Al³⁺ ions in living cells. PY-I has a phenolic group as a binding site at the 3-position of the pyrazoline ring which is responsible for its sensing of metal ions. Nevertheless, PY-II has no hydroxyl groups in the phenyl ring and was unable to sense metal ions; however, PY-II has good photophysical properties which make it a suitable fluorescent material.