Crystallographic, Topological, Antidiabetic, and Docking Evaluation of an Azo-Enamine Ligand and its Triphenyltin(IV) Coordination Polymer

Abstract

The ligand 2-((E)-((Z)-3-(((2-hydroxyethyl)amino)methylene)-4-oxocyclohexa-1,5-dien-1-yl)diazenyl)benzoic acid (H₃L) was synthesized and structurally characterized for the first time. Single-crystal X-ray diffraction study confirmed that H₃L adopts a stable azo-enamine tautomeric form in solid state stabilized by intramolecular hydrogen bonding. The corresponding polymeric triphenyltin(IV) complex [Ph₃Sn(IV)HL] (1) was also synthesized and characterized by FTIR, multinuclear NMR, and X-ray crystallography. Structural analysis revealed a five-coordinate distorted trigonal bipyramidal geometry around the Sn(IV) center. Topological analysis of both structures highlighted distinct hydrogen-bonded and valence-bonded network topologies (2C1 and sql types, respectively), underscoring supramolecular structural features. In vitro α-glucosidase inhibition studies demonstrated that H₃L possesses strong inhibitory activity, particularly in DMSO (79.36%, IC₅₀ ≈ 26.8 µg/mL), outperforming the standard inhibitor acarbose, while complex 1 showed negligible inhibition. Molecular docking against α-glucosidase (PDB ID: 5ZCB) supported these findings, showing that (H₃L) exhibits a more favorable binding affinity (MolDock score: –87.92 kcal/mol) and a stronger interaction profile than acarbose. These results highlight the potential of (H₃L) as a promising lead compound for the development of α-glucosidase inhibitors.