Comparative Studies of Structural, Thermal, Optical, and Electrochemical Properties of Azines with Different End Groups with Their Azomethine Analogues toward Application in (Opto)Electronics

Abstract

Two series of azines and their azomethine analogues were prepared via condensation reaction of benzaldehyde, 2-hydroxybenzaldehyde, 4-pyridinecarboxaldehyde, 2-thiophenecarboxaldehyde, and 4-(diphenylamino)benzaldehyde with hydrazine monohydrate and 1,4-phenylenediamine, respectively. The structures of given compounds were characterized by FTIR, (1)H NMR, and (13)C NMR spectroscopy as well as elemental analysis. Optical, electrochemical, and thermal properties of all compounds were investigated by means of differential scanning calorimetry (DSC), UV-vis spectroscopy, stationary and time-resolved photoluminescence spectroscopy, and cycling voltammetry (CV). Additionally, the electronic properties, that is, orbital energies and resulting energy gap were calculated theoretically by density functional theory (DFT). Influence of chemical structure of the compounds on their properties was analyzed.

(E)-2-[(2-hydroxybenzylidene)amino]phenylarsonic acid Schiff base: Synthesis, characterization and theoretical studies

“…The signal observed at 10.30 ppm was assigned to the proton H6 attached of oxygen atom of the AOH group, which was shifted to high field compare to corresponding chemical reagent, as well for the other salicylaldehyde Schiff bases reported [33]. The singlet signal at 8.92 ppm was assigned to a unique proton H1 attached to a double bond (ACH@NA), which is in agreement with others Schiff bases reported in the literature [32]. The signal between 8.06 and 8.04 ppm, with an integration for two protons H2 and H5, was assigned to the phenylarsonic group with J H-H = 7.5 Hz.…”

“…1. The principal band at 1614 cm À1 was assigned to the double bond stretching of (azomethineAC@NA) conjugated to an aromatic ring [31,32]. Furthermore, the IR spectrum did not exhibit a broad and medium intensity band around 1659 cm À1 , which would correspond to vibration m(C@O) for the salicylaldehyde as well as the m(NAH) for the two NAH of ANH 2 moiety giving evidence of the formation of compound.…”

“…p ⁄ and n ? p ⁄ transitions [32,34]. On the other hand, Schiff bases, especially salicylaldehyde derivatives, are some of the most important compounds in photochemistry because of the excited state intramolecular proton transfer to change the phenol form into the keto form, which results in a detectable fluorescence signal accompanied by a large stokes shift [35].…”

Synthesis, structures and electronic properties of Co(III) complexes with 2-quinolinecarboxaldehyde thio- and selenosemicarbazone: A combined experimental and theoretical study

“…9,50 The absorption maxima around 350 nm corresponds to the π-π* transition of the azomethine group. 9,51 The presence of intraligand π-π* transitions, as well as the strong ligand-to-metal charge transfers (LMCT) around 400 nm obscure the weak, spin allowed d-d transitions in the experimental absorption spectra. Based on TD-DFT calculations, the major transitions of the first allowed 1 T 1g ← 1 A 1g band are at 500 and 570 nm for complexes 1 and 2, respectively.…”

Visualized acid–base discoloration and optoelectronic investigations of azines and azomethines having double 4-[N,N-di(4-methoxyphenyl)amino]phenyl terminals

“…3 Among the π-conjugated compounds, azines having N−N linked diimines (R−CH=N−N=CH−R) and azomethines bearing imine linkages (−CH=N−), are found to be good candidates for multifunctional materials. 5,7 On the other hand, azomethines exhibit high chemical, oxidative, and reductive resistance and interesting photophysical properties. The optical properties of a molecule are strongly dependent on its electron distribution.…”