Synthesis of Di(thiophen-2-yl) Substituted Pyrene-Pyridine Conjugated Scaffold and DFT Insights: A Selective and Sensitive Colorimetric, and Ratiometric Fluorescent Sensor for Fe(III) Ions

In this context, we used the multicomponent Chichibabin pyridine synthesis reaction to synthesize a novel di(thiophen-2-yl) substituted and pyrene-pyridine fluorescent molecular hybrid. The computational (DFT and TD-DFT) and experimental investigations were performed to understand the photophysical properties of the synthesized new structural scaffold. The synthesized ligand displays highly selective fluorescent sensing properties towards Fe³⁺ ions when compared to other competitive metal ions (Al³⁺, Ba²⁺, Ca²⁺, Cd²⁺, Co²⁺, Cr³⁺, Cu²⁺, Fe²⁺, Hg²⁺, Na⁺, Ni²⁺, Pb²⁺, Sr²⁺, Sn²⁺ and Zn²⁺). The photophysical properties studies reveal that the synthesized hybrid molecule has a binding constant of 2.30 × 10³ M⁻¹ with limit of detection (LOD) of 4.56 × 10⁻⁵ M (absorbance mode) and 5.84 × 10^–5 M (emission mode) for Fe³⁺ ions. We believe that the synthesized pyrene-conjugated hybrid ligand can serve as a potential fluorescent chemosensor for the selective and specific detection of Fe³⁺ ions.