Acid-responsive behavior promoted by imine units in novel triphenylamine-based oligomers functionalized with chromophoric moieties

Bejan, Andra-Elena; Damaceanu, Mariana‐Dana

doi:10.1016/j.jphotochem.2019.04.010

Cited by 12 publications

(10 citation statements)

References 48 publications

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“…This effect could explain why the PAzMCs show emission in acid media, but not in non‐acidic media, and also why the emission is identical between the samples. On the other hand, the Stokes shifts were found near to 30 and 36 nm for PAzMC1 and PAzMC2, respectively, with a moderate overlap of the absorption and emission spectra, respectively (Fig. ).…”

Section: Resultsmentioning

confidence: 92%

“…When acid is added to the DMSO polymer solutions, the protonation of the imine functions activates their emission by promoting the radiative decay of the absorbed photons. This fact, together with the values of Stokes shifts, would avoid the phenomenon of re‐absorption, which is important for possible applications as potential materials in the optoelectronics field …”

Section: Resultsmentioning

confidence: 99%

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New cardo silylated poly(azomethine)s containing 9,9′‐diphenylfluorene units as materials with Brønsted acid‐dependent fluorescence

Hauyon

Garrido‐Gatica

Sobarzo

et al. 2019

Polymer International

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Aromatic poly(azomethine)s have been studied due to their attractive properties such as high thermal stability, semiconducting behavior and the ability to coordinate species with their imine units (CN). In this paper, the synthesis and characterization of two novel silylated poly(azomethine)s containing cardo units are reported. These materials were highly soluble in organic solvents such as chloroform and m‐cresol and were thermally stable, and PAzMC1 exhibited a high glass transition temperature value (287 °C), while that for PAzMC2 was not observed. UV–visible spectrophotometry revealed absorption bands related to the aromatic backbone of both PAzMCs, 300–285 nm in tetrahydrofuran and 310–301 nm in dimethylsulfoxide, and bands attributed to the conjugated imine unit at around 350 nm. In order to investigate the phenomenon of the emission of fluorescence promoted by dopant agents with regard to potential optoelectronic applications, the materials were doped with H2SO4 and their optical and electrochemical properties investigated. Thus, the absorption band of the imine group was suppressed due to the nitrogen atoms being protonated. Fluorescence spectroscopy analysis developed in dilute solutions of polymers showed no emission from the undoped polymers, whereas the acid‐doped species emitted fluorescence in the UV and violet regions (322 nm). Cyclic voltammetry measurements were carried out and HOMO–LUMO energies were estimated. This study provides a starting point for the development of new poly(azomethine)s with doping‐dependent emission. © 2019 Society of Chemical Industry

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Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 99%

New cardo silylated poly(azomethine)s containing 9,9′‐diphenylfluorene units as materials with Brønsted acid‐dependent fluorescence

Hauyon

Garrido‐Gatica

Sobarzo

et al. 2019

Polymer International

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“…The possibility of obtaining large, elastics surfaces of organic materials, using wet methods, is also important from a practical point of view. Other advantage of organic compounds is the possibility of suitable modification of their chemical structure (by different substitutions or doping) to obtain desired properties and electronic structure, towards optoelectronic applications [ 5 , 6 ]. One of the interesting groups of organic semiconductors are azomethines and polyazomethines, known also as imines or Schiff-bases.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Alkyl Substitution of Novel Imines on Their Supramolecular Organization, towards Photovoltaic Applications

et al. 2021

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Three novel conjugated polyazomethines have been obtained by polycondensation of diamines consisting of the diimine system, with either 2,5-bis(octyloxy)terephthalaldehyde or 9-(2-ethylhexyl)carbazole-3,6-dicarboxaldehyde. Partial replacement of bulky solubilizing substituents with the smaller side groups has allowed to investigate the effect of supramolecular organization. All obtained compounds have been subsequently identified using the NMR and FTIR spectroscopies and characterized by the thermogravimetric analysis, differential scanning calorimetry, cyclic voltammetry, UV–Vis spectroscopy, and X-ray diffraction. Investigated polymers have shown a good thermal stability and high glass transition temperatures. X-ray measurements have proven that partial replacement of octyloxy side chains with smaller methoxy groups induced a better planarization of macromolecule. Such modification has tuned the LUMO level of this molecule and caused a bathochromic shift of the lowest energy absorption band. On the contrary, imines consisting of N-ethylhexyl substituted carbazole units have not been so clearly affected by alkyl chain length modification. Photovoltaic activity of imines (acting as a donor) in bulk-heterojunction systems has been observed for almost all studied compounds, blended with the fullerene derivative (PCBM) in various weight ratios.

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“…30,32 In addition, protonation and doping of imine polymers have been largely involved over the time to modulate their physico-chemical properties. [32][33][34][35][36] It is well known that using suitable dopants, for instance, iodine, charge carriers like polarons and bipolarons can be generated across the conjugated systems of imine oligomers and polymers which enable better electron conduction. 16 The properties induced by doping and/or protonation of oligomers and polymers containing the imine bond have been thoroughly analyzed by various researchers who identified as the main changes the red or blue shift of the absorption bands and the decrease of the energy bandgap in cyclic voltammetry and/or ultraviolet-visible (UV-Vis) absorption studies of protonated/doped imine derivatives.…”

Section: Introductionmentioning

confidence: 99%

“…16 The properties induced by doping and/or protonation of oligomers and polymers containing the imine bond have been thoroughly analyzed by various researchers who identified as the main changes the red or blue shift of the absorption bands and the decrease of the energy bandgap in cyclic voltammetry and/or ultraviolet-visible (UV-Vis) absorption studies of protonated/doped imine derivatives. 20,33,37,38 The mechanism involved in the iodine doping of imines has been firstly explained for branched TPA containing imine derivatives in terms of electron extraction from the double imine bonds that induce the change of the benzoid skeleton into a quinoid one. 39 The iodine doping is a largely used method for practical applications of such compounds, especially in light-emitting diodes and solar cells.…”

Section: Introductionmentioning

confidence: 99%

Opto-Electronic Properties Modulation Through Iodine Doping of Imine- and Triphenylamine-Based Oligomers

Bejan¹,

Diaconu

Damaceanu³

2021

Journal of Elec Materi

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Conjugated imine derivatives are of particular interest for the opto-electronic field since their opto-electronic properties can be finely tailored by protonation or doping of the imine unit, e.g. by iodine doping. In this context, four triphenylamine-based oligoimines were subjected to iodine doping in the solid state and thoroughly investigated with respect to the electronic structure modulation induced by doping. The iodine doping process was analyzed by several methods, such as cyclic voltammetry, ultraviolet-visible absorption and Fourier-transform infrared (FTIR) spectroscopy. In addition, a four-point probe technique was applied to measure the electrical conductivities of both the doped and undoped oligoimines. We have noticed changes of the electronic absorption spectra that consisted of the appearance of a new absorption band due to dopant-induced states within the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap. Due to the p-type doping process, a distinct reduction of the energy bandgap occurred, being contingent on the formation of imine polaron states, according to the proposed mechanisms. This was confirmed by FTIR spectroscopy, which indicated the presence of the quinoid skeleton in polaronic species formed by doping. Nevertheless, the iodine doping process of oligoimines was accompanied by new redox processes in both the anodic and cathodic regions. Electrochemical data indicated that iodine-doped oligoimines exhibit a higher electronic affinity (LUMO) and a slightly lower energy bandgap compared to pristine forms. The electrical conductivity values of the undoped oligoimines were found in the range of 6.4 9 10 À7-8.14 9 10 À8 S/ cm and increased eight times after oligoimine iodine-doping only in the case of two oligomers. Since doped oligoimine films display better features compared to their pristine forms, they could find applications in opto-electronic devices.

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Acid-responsive behavior promoted by imine units in novel triphenylamine-based oligomers functionalized with chromophoric moieties

Cited by 12 publications

References 48 publications

New cardo silylated poly(azomethine)s containing 9,9′‐diphenylfluorene units as materials with Brønsted acid‐dependent fluorescence

New cardo silylated poly(azomethine)s containing 9,9′‐diphenylfluorene units as materials with Brønsted acid‐dependent fluorescence

The Effect of Alkyl Substitution of Novel Imines on Their Supramolecular Organization, towards Photovoltaic Applications

Opto-Electronic Properties Modulation Through Iodine Doping of Imine- and Triphenylamine-Based Oligomers

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