Synthesis and characterization of polyphenol derived from Schiff bases containing methyl and carboxyl groups in the structure

High temperature stable conjugated polyazomethines containing naphthalene moiety: Synthesis, characterization, optical, electrical and thermal properties

A series of azomethine diol monomers containing naphthalene moiety were synthesized and oxidatively polymerized in aqueous alkaline medium using NaOCl as oxidant. The structure of the monomers and polymers was characterized by using various spectroscopic techniques. PL spectra of polymers are exhibiting good emission with high Stokes shift values than the monomers due to their polyconjugated structure. The electrical conductivity of polymers was measured by a two-point probe technique, and it increases with an increase in iodine vapour contact time up to 144 h. The electrical conductivity values were correlated with the charge density on azomethine nitrogen obtained from the Hückel calculation method. The dielectric properties of polymers were studied at different temperatures in the frequency range from 50 Hz to 5 MHz. The synthesized polyazomethines have recorded high thermal stability and are shown by carbon residue of around 50% at 800 °C in the thermogravimetric analysis.

Investigation of aggregation induced emission in 4-hydroxy-3-methoxybenzaldehyde azine and polyazine towards application in (opto) electronics: synthesis, characterization, photophysical and electrical properties

An azine monomer 4-hydroxy-3-methoxybenzaldehyde azine was synthesized by refluxing with ethanolic solution of vanillin with hydrazine hydrate. It was then converted into polyazine by oxidative polymerization. The structure of azine and polyazine was characterized by FT-IR, UV–visible, ¹H-NMR and ¹³C-NMR. Spectral results suggest the formation of polymer, through C–C and C–O–C coupling of the phenylene and oxyphenylene. The relationship between the structures and photophysical properties of azine and polyazine was studied. Both azine and polyazine show, aggregation induced emission with increase in concentration in DMSO solution. The single crystal structure of azine suggesting the various inter and intra molecular interactions rigidify the conformation and locked the intramolecular rotations of the phenyl rings in the molecule. The inhibition of intramolecular rotation, J- aggregation and increase of conjugation impart the fluorescence in aggregated state. Additionally, the electronic properties namely orbital energies and resulting energy gap calculated theoretically by density functional theory (DFT).