Al3+ induced hydrolysis of rhodamine-based Schiff-base: Applications in cell imaging and ensemble as CN- sensor in 100% aqueous medium

A novel Schiff base having terephthaldehyde appended with two rhodamine units has been synthesized, which exhibited fluorogenic and chromogenic response on binding with Al3+ ions in 100% aqueous system at pH 7.04. The binding of compound 1 with Al3+ ions was not hindered by the presence of background metal ions. The coordination mode of compound 1 was established by Job's plot method that has been found to be 1:1 stoichiometry with Al3+ ions. The compound 1 could detect Al3+ as low as 1.68 mu M in a pH range of 6-10. NMR and mass spectrometry analysis revealed that the Al3+ induced hydrolysis occurs on one side of the Schiff base and led to the formation of free-CHO group. The hydrolysed ensemble (1.Al3+) was used for detection of CN- ions (H2O-HEPES buffer, pH 7.04), accompanied by colorimetric and fluorimetric changes. Compound 1 was used to detect Al3+ ions in A549 cells through live cell imaging technique.