Synthesis and Study of Arylenevinylene and Aryleneimine-Type Polymers Containing N-Hexyl-3.6-Carbazolyl Groups

Abstract

Two monomers with preformed Schiff base and arylenevinylene structure and final bromine substituents were synthesized by coupling of 3-formyl-6-bromo-N-hexyl-carbazole with 1,4-phenylenediamine and tetraethyl-p-xylylene diphosphonate, respectively. These compounds were used to synthesize arylenimine and arylenevinylene polymers containing N-hexyl 3,6-carbazolylydiyl units in the main chain by dehalogenative coupling reactions via organometallic reductive catalysis (Ni 0 .bipy). The polymers were characterized by spectral methods (Fourier transform-infrared, 1 H NMR, UV-vis and fluorescence) as well as gel permeation chromatography and differential scanning calorimetry.

New symmetrical conjugated thiophene-azomethines containing triphenylamine or carbazole units: Synthesis, thermal and optoelectrochemical properties

“…This was due to the fact that the carbazole unit is more planar than the triphenylamine unit having the nitrogen atom linked to three electron-rich phenyl groups in a propeller-like geometry. 27 , 28…”

“…From the electrochemical data it can be noted that the triphenylamine- oligoazomethine was more easily oxidized than carbazole-oligoazomethine. In comparison with the redox behavior of oligomers that possess in their structures triphenylamine ( E ox1 = 0.88 V versus Ag/AgCl) or carbazole ( E ox1 = 0.82 V versus Ag/AgCl) units linked through vinylene segments by phenyl or biphenyl moieties, 27,28 the redox behavior of the oligoazomethines showed that the higher oxidation potential values might be caused by the presence of thiophene units or –CN groups. Due to the electron-withdrawing character of cyano groups the oxidation potentials of the periphery amine groups were increased.…”

“…It can be concluded that the band gap energy (HOMO–LUMO gap) was smaller for triphenylamine-based oligoazomethine (O1) compared with the carbazole one, but both oligomers presented larger band gap values than oligoarylamine-vinylene containing triphenylamine ( E g = 1.87 eV) or carbazole units ( E g = 2.11 eV). 27,28 The band gap values are directly related to the linearity of the conjugation backbone, and thus, the larger band gaps value was attributed to the interruption of the linearity of the conjugated backbone. So, based on these experimental data it can be concluded that oligomers with triphenylamine units in their structure had lower band gap energy than the carbazole one, and this can be explained by higher conjugation structure.…”

“…The syntheses of the starting products based on triphenylamine and carbazole were carried out similar to previously reported methods. 27–29 2,5-diamino-3,4-dicyanothiophene was synthesized according to the reference. 30 N , N ′-Dimethylformamide (DMF), isopropyl alcohol and other solvents (all from Aldrich) were used as received or dried by usual methods and distilled under reduced pressure.…”

“…This structural arrangement of carbazole units along the polymeric backbone affects the physical properties and especially the thermal stability of their corresponding polymers . 26–29…”