Synthesis of model ligand N-propyl(2-pyridyl)methanimine. The model ligand Npropyl(2-pyridyl)methanimine is synthesized via a one-step condensation reaction. Under vigorous stirring at room temperature, propylamine (5.9 g, 0.1 mol) is added dropwise into a 50 ml round-bottom flask containing 2-pyridinecarboxaldehyde (10.7 g, 0.1 mol). 3A molecular sieves are added into the mixture to adsorb water. The system is reacted overnight, and the product is filtered to remove the molecular sieves, obtaining yellow colored liquid (11.2 g, yield 73%). Hz, 3H) (Figure ).