Coordinative, conformational and motional behaviour of triazine-based ligand strands on binding of Pb(II)cations

The coordinative behaviour of two bis(hydrazone)triazine-based ligands in the presence of Pb(II) was investigated. Free ligand, pincer-like and stick-like complexes' X-ray structures are described. The ligands adopt a pyridine-like coordinative behaviour for Pb(II)/ligand molar ratio equal to 1/2 and 1/1, and a pyrimidine-like coordinative behaviour for Pb(II)/ligand molar ratio equal to 2/1. The complexation processes are reversible and may be modulated by external stimuli. They generate conformational and motional behaviour through interconversion of three entities, free ligand, pincer and stick complex.