A Review on 2,6-Diformyl-4-methylphenol Derived Schiff Bases as Fluorescent Sensors

Abstract

2,6-Diformyl-4-methylphenol fluorophore derived Schiff base sensors detect metal ions such as Zn2+, Al3+, Hg2+, Cd2+, Sn2+ and Cu2+ with high sensitivity and selectivity through changes in fluorescence intensity based on CHEF, ICT, FRET, ESIPT, C=N isomerization and PET mechanism. Several anions viz. HPO4 2–, H2PO4 –, PO4 3–, AsO3 3–, H2AsO4 –, AsO2 –, PPi (pyrophosphate), I–, F– and N3 – were also detected through intermolecular hydrogen bonding (between sensor and anion) based on TICT, PET, CHEF, ESIPT and aggregation induced emission mechanism. Selectivity and sensitivity for these metal ions and anions were achieved by introducing various amines to core fluorophore 2,6-diformyl-4-methylphenol. Majority of these fluorescent sensors were Zn2+ ion selective. Due to the filled d10 electronic configuration of Zn2+ ion usually does not show deactivation of excited state via any electron or energy transfer mechanisms. Both solvent dependent and independent ten multi-ion selective sensors are found. This review will consolidate on 2,6-diformyl-4-methylphenol derived Schiff base fluorescent chemosensors.