DC electrical conductivity of some oligoazomethines

Abstract

Six aromatic oligoazomethines were synthesized containing seven benzene rings each. The terminal rings were substituted with different groups, namely, H, Cl, NO2, OH, OCH3 and CH3. The synthesis was carried out by condensing the para‐substituted benzaldehydes with benzidine to give the three‐ring compound, which was then condensed with terephthaldehyde to give the respective seven‐benzene‐ring oligomers. The oligomers were characterized by elemental analysis, electronic spectra, Fourier‐transform infrared and thermal analysis. The oligomers were used to investigate the effects of their molecular structure on their electronic spectra, as well as their thermal, electronic and electrical properties. The different conformers were reported and compared. The DC electrical conductivity variation of oligoazomethines was studied in the temperature range 300–500 K after annealing for 24 h at 100 °C and after doping with 5% I2. An attempt was made to relate the DC electrical conductivity, electronic properties and thermal properties to the chain length, substituted groups and coplanarity. The fairly low conductivity obtained was attributed to the non‐linearity of the rings in the chain. The different groups (neutral, electron withdrawing or electron donating) attached at the ends of the oligomer showed no influence upon the conductivity of the different oligomers. The action of doping gave almost the same enhancement as that noticed in the case of a long‐chain polymer. The DC electrical conductivity was interpreted using the band energy model. The seven‐benzene‐ring oligomer gave the same DC electrical conductivity as the long‐chain polymer. Copyright © 2004 Society of Chemical Industry

Optoelectronic property tailoring of conjugated heterocyclic azomethines – the effect of pyrrole, thiophene and furans

“…The reduced E pa is a result of the increased degree of conjugation and confirms the extended delocalization of the azomethines. The higher E pa and energy gap (E g ) of the homoaryl derivatives (22)(23)(24)(25) relative to their all-heterocyclic counterparts corroborate the limited degree of conjugation that was spectroscopically observed. The collective electrochemical data confirm that both the anodic and cathodic potentials can be tailored by incorporating different heterocycles into the azomethines and via the number of azomethine bonds.…”

“…This is a result of inherent twisting around the aryl-azomethine bonds that limits their degree of conjugation. [10,[19][20][21][22][23][24][25][26][27] Enhanced azomethine optoelectronic properties comparable to their vinylene analogues are however possible with thiophene derivatives. [6,7,28,29] This is in part a result of coplanarization of the thiophene-azomethine moieties.…”

<b>Synthesis, characterization, thermal degradation and electrical conductivity of poly-4-[(pyridin-2-yl-imino)methyl]benzene-1,3-diol and polymer-metal complexes</b>

“…Polyimines or Schiff base polymers, which are also named polyazines, were first reported by Adams et al in 1923 [1]. Research interest in polyazomethines continues owing to their different characteristics such as chelating properties [2,3], thermal stability [4,5], liquid crystal properties as well as intrinsic conductivity [6][7][8][9][10]. Polyazomethines are generally synthesized by polycondensation reactions, a method that has some disadvantages, among them being the necessity to ensure special reaction conditions such as high temperature and the use in some cases of special catalysts [11].…”

Characterization, Thermal Degradation, Electrical Conduction and Microbial Activity of Polymer and Its Polymer-Metallic Complexes

“…Research interest in polyazomethines continues owing to their various characteristics such as chelating properties [1,2] thermal stability [3,4], liquid crystal properties as well as intrinsic conductivity [5,6]. A new method of synthesizing polyazomethine was reported i.e.…”