Real time sensor for Fe3+, Al3+, Cu2+ & PPi through quadruple mechanistic pathways using a novel dipodal quinoline-based molecular probe

• Quinoline-based probe with multiple functionalities was designed and synthesized. • It was utilized for the facile detection of Fe 3+ and Al 3+ through a turn-on fluorimetric response with very low detection limits. • Complexes of Fe 3+ and Al 3+ formed in solution state were capable of sensing PPi in-situ by turning off the fluorescence intensity. • The probe could detect Cu 2+ ion in semi-aqueous medium through sharp change in colour. • Investigations showed that the probe can be efficiently used as a sensor for pH. • Use of time dependent studies, reversibility and paper strip experiments have been done to demonstrate its performance on a practical front. A quinoline-based small molecular probe, H 2 L was designed, synthesized and characterized by different spectroscopic methods. It was utilized as a multi-responsive probe for the detection of Fe 3+ , Al 3+ , Cu 2+ and PPi. It showed very selective instant turn-on fluorimetric response towards Fe 3+ and Al 3+ with a detection limit in nanomolar range. Solutions of H 2 L containing Fe 3+ or Al 3+ could sequentially sense PPi by a turn-off mechanism. Also, H 2 L could determine the presence of Cu 2+ very selectively among a series of other metal ions by a sharp change in colour. Detection of Cu 2+ through colorimetry was further investigated by systematic UV-Vis studies and the potential of H 2 L to act as a potential colorimetric sensor for Cu 2+ was suitably established. Filter-paper strip experiments were conducted to demonstrate the practical utility of the proposed sensor. Potential applications of H 2 L as a sensor for pH in the acidic range has also been explored.