Azine Based Oligoesteric Chemosensors for Cu²⁺ Ion Detection: Synthesis, Structural Characterization, and Theoretical Investigations

Synthesized monomer and its three oligoesters were characterized by techniques such as ¹H, ¹³C{¹H}, IR, UV, GPC and applied to chemosensor applications. A series of metal ions was studied with fluorophores to evaluate the sensitivity towards Cu²⁺ ion. The fluorophores results exhibit the selective and sensitive “Turn off” fluorescence response with Cu²⁺ ion in DMF/H₂O (1:1, pH: 7.4, fluorophore: 5 µM) solution. Binding stoichiometry and binding constant of fluorophores were calculated using Stern–Volmer equation and Benesi–Hildebrand plots, respectively. Structure of fluorophores were studied using DFT, B3LYP/6–311 +  + G(d,p) level basis set. Quenching mechanisms and electrical properties of fluorophores were explained with theoretical outcomes. Iodine doped and undoped oligoesters electrical conductivity were studied in solid-state and the conductivity was gradually increased with increase the contact time of iodine with oligoesters. At different frequencies and temperatures, the dielectric measurement was calculated using the two-probe method. Among all oligoesters, DMDAP exhibited high electrical conductivity and DMDMP has a higher dielectric constant value than other oligoesters.