Influence of Donor‐Substituents on Triphenylamine Chromophores Bearing Pyridine Fragments

Abstract

Efficient synthetic routes that combine different palladium‐catalyzed cross‐coupling reactions have been developed for the preparation of a new family of push‐pull derivatives in which pyridine was used as the acceptor group and different para‐substituted diphenylamines as the donor groups. All compounds showed absorption in the UV/Vis region and blue‐green emission with high quantum yields. Significant red shifts were observed in the absorption and fluorescence emission maxima on increasing the electron‐donating ability of the substituents or on incorporating a π‐conjugated linker. This finding can be explained on the basis of enhanced intramolecular charge transfer (ICT). Strong emission solvatochromism confirmed the formation of an intramolecular charge‐separated emitting state. The HOMO‐LUMO energy gaps have been estimated by experimental electrochemical measurements and the results were interpreted with the aid of DFT calculations. The thermal behavior of all materials has also been studied by differential scanning calorimetry.

Tuning the Photophysical Properties of Push‐Pull Azaheterocyclic Chromophores by Protonation: A Brief Overview of a French‐Spanish‐Czech Project

“…Unfortunately, the protonated forms of these chromophores were not emissive in any case. [38] R e v i s e d m a n u s c r i p t Figure 21. Chemical structures of compounds 71-76.…”

Push–Pull Derivatives Based on 2,4′-Biphenylene Linker with Quinoxaline, [1,2,5]Oxadiazolo[3,4-B]Pyrazine and [1,2,5]Thiadiazolo[3,4-B]Pyrazine Electron Withdrawing Parts

“…Push-pull molecular materials have found applications as fluorescent sensors [7][8][9][10], dye-sensitized solar cells (DSSC) [11][12][13][14], nonfullerene organic photovoltaic (OPV) materials [15][16][17], and numerous other optoelectronic devices [18][19][20][21]. The intramolecular charge transfer (ICT) in push-pull molecular materials can be modulated either by playing on the A/D couple [1,2,22,23] or by changing the nature and length of the π-conjugated bridge [1,2,24,25]. In this context, π-deficient heterocycles are particularly interesting as A part, as follows: the electron-lone pairs of heteroatoms of the heterocyclic core can be indeed used for protonation, complexation, alkylation, or the formation of a hydrogen bond, modifying their electron-withdrawing character and tuning the optical properties of corresponding push-pull structures by redistribution of charge density [26][27][28][29][30][31].…”

Copper(I) Donor–Chromophore–Acceptor Assembly for Light-Driven Oxidation on a Zinc Oxide Nanowire Electrode

“…The UV–vis spectra of both the acceptor ( A ) and donor ( D ) ligands exhibit an intense absorbance below λ = 300 nm attributed to π → π* transitions localized on neocuproine (Figure A). The spectrum of donor D shows another intense band at λ = 365 nm assigned to a π → π* transition on the triphenylamine moiety by comparison to the literature . The vibronic bands centered at 370 nm and 390 nm in the spectrum of A are assigned to phenazine π → π* transitions.…”

“…The spectrum of donor D shows another intense band at λ = 365 nm assigned to a π → π* transition on the triphenylamine moiety by comparison to the literature. 60 The vibronic bands centered at 370 nm and 390 nm in the spectrum of A are assigned to phenazine π → π* transitions. As expected, UV− vis spectra of both A-Cu(I)-D and A-Cu(I) exhibit broad 1 MLCT absorption bands (centered at ca.…”