Ionophoric azoaromatics: Synthesis, isolation and complex formation with alkali metal ions

• Design and synthesis of ionophoric azoaromatic ligands.
• Ortho Caromatic–N bond fusion.
• Sodium ion encapsulation.

Tailor made synthesis of the azoaromatics, HL1–HL2 [HL = 2-(arylamino)phenylazopyridine] containing ionophoric crown moiety is described. Coordination induced C–N bond fusion synthetic protocol was successfully implemented for the synthesis of these compounds that are subsequently characterized using various spectroscopic techniques. Single crystal X-ray structures of the cobalt compounds, [1a]+ and [1b]+, clearly characterize the ionophoric ligand and its tridentate coordination mode via deprotonation of the secondary amine proton. Moreover, the structural analysis of [1b]+ reveals the receptor ability of benzo-15-crown-5 towards alkali metal ion in solid state. This complex shows two O…π contact, which resulted in the formation of a helical 1D supramolecular chain. Electrochemical studies exhibit anodic shift of the reduction potentials of the CoIII center in the presence of Na+ thereby indicating complexation of these ions to the crown moiety.

Coordination induced C–N bond fusion synthetic protocol was successfully implemented for the synthesis of cobalt complexes of crown-ether function containing 2-(arylamino)phenylazopyridine ligands. Structural analysis of one of the complexes reveals the receptor ability of benzo-15-crown-5 towards sodium ion in solid state. Supramolecular helical architecture via intermolecular contacts in mixed ligand complex has been identified.Figure optionsDownload as PowerPoint slide