Solvent-free synthesis, spectral, crystal study and DFT calculations of (E)-1-benzyl-N-(4-fluorobenzylidene)piperidin-4-amine and (E)-1-benzyl-N-(naphthalen-2-ylmethylene)piperidin-4-amine

Abstract

• Synthesis of ( E )-1-benzyl-N-(4-fluorobenzylidene)piperidin-4-amine ( I ) and ( E )-1-benzyl-N-(naphthalen-2-ylmethylene)piperidin-4-amine ( II ) by solvent-free greener method. • FT-IR, NMR and Single crystal X-ray diffraction studies confirmed the formation of compound I and II . • Crystal structure of compound I and II having orthorhombic and monoclinic, and its geometric parameters were compared with the theoretical values. Two Schifff's bases ( E )-1-benzyl-N-(4-fluorobenzylidene)piperidin-4-amine ( I) and ( E )-1-benzyl-N-(naphthalen-2-ylmethylene)piperidin-4-amine ( II) were prepared by ZnFe 2 O 4 catalyst assisted microwave irradiated condensation method under solvent-free conditions. Synthesised Schiff's bases ( I ) and ( II ) were crystallized by a slow evaporation technique. High-quality single crystals of ( I) and ( II ) were developed from ethanol and therefore reasonable crystal measurements are 0.28 × 0.26 × 0.21 (I) and 0.21 × 0.25 × 0.35 mm (II) and these crystals possess orthorhombic and monoclinic crystal system with the space group of P2 1 and P2 1 /c respectively. Theoretical calculations were performed utilizing DFT (B3LYP) strategy with 6-31G(d,p) because of the basis set to derive the optimized geometry, dipole moment, HOMO-LUMO energy, molecular electrostatic potential, Mulliken charge population and first-order molecular hyperpolarizality (β). Further, these Schiff's bases were characterized by elemental analysis, FT-IR, 1 H & 13 C NMR and HR-MS spectroscopy.