Design and synthesis of bis-coumarinyl methanes from 4-hydroxy-coumarin and aldehydes catalysed by Amberlyst 15 via dual C-C coupling: introducing coumarin based thin film organic nano-materials for memory devices

摘要

An efficient one pot synthesis of various bis-coumarinyl methane derivatives was investigated by condensing a series of aldehydes with 4-hydroxy coumarin in the presence of Amberlyst 15 catalyst under refluxing conditions in ethanol-water (1:1). This one pot domino Knoevenagel condensation/Micheal addition reaction provides excellent yield of bis-coumarinyl methane derivatives with lots of advantages like shorter reaction time, eco-friendly reaction medium, simple work up, recyclability of the catalyst and chromatography-free purification. Moreover, the synthesized compound was exploited to develop bis-coumarinyl methylene-based nanostructured materials of special interests which were investigated by UV-Vis, fluorescence spectroscopy, imaging in scanning electron microscope and atomic force microscope. Our UV-Vis and fluorescence study indicated that some of the organic compounds are organized as H-aggregate in the thin film. We also investigated I-V characteristics of the thin film of some of the selective compounds which showed write-once-read-more memory switching behaviour onto the thin film under investigations.