Theoretical and Experimental Investigation of a Ferrocene‐Based Double Azine as a Selective Chemical Sensor

ABSTRACT This study was conducted to validate and complement the experimental data on a ferrocene‐based unsymmetrical azine [1,4‐Bis((ferrocenylidenehydrazono)methyl)benzene] and its complexes with Cu 2 + , Co 2 + , Zn 2 + , and Hg 2 + ions. Due to the lack of crystal structures and unclear thermodynamic behavior for the L igand and its complexes, density functional theory (DFT) calculations were employed to interpret the experimental findings and elucidate the unknown geometries and properties. The L igand ’s reactivity was investigated in different multiplicities, the molecular electrostatic potential (MEP) mapping, and HOMO‐LUMO analysis. The electronic stability arising from conjugation and charge delocalization was studied using the quantum theory of atoms in molecules (QTAIM). The complexation in gas and solvent phases was modeled using the polarizable continuum model (PCM). The L igand exhibited excellent multichannel chemosensor behavior toward Cu 2 + ions. Thermodynamic functions (such as enthalpy, entropy, and Gibbs free energy) were calculated at 293.15 K. The 1 H and 1 3 C NMR chemical shifts were estimated using the GIAO method and showed good agreement with experimental data. The fundamental vibrational modes were assigned in detail using Potential Energy Distribution (PED) analysis, and the computed values strongly correlated with the experimental results. Furthermore, new spectra related to the Cu‐complex were predicted, which may be useful for future sensor design.