Synthesis, Photophysical and Electrochemical Properties of Novel D-π-D and D-π-A Triphenylamino-Chalcones and β-Arylchalcones

Abstract

A series of triphenylamino (TPA)-chalcones and triphenylamino-β-arylchalcones, displaying either D-π-D or D-π-A architecture, were synthesized through aldol condensations and Heck reactions. The chalcone derivatives display intense absorption bands ranging from 389 to 432 nm and molar extinction coefficients of ca. 10 5 L mol-1 cm-1 corresponding to π-π* electronic transitions. The photoluminescence emissions are peaked between 470 and 563 nm with large Stokes shifts (80-131 nm), attributed to charge transfer in the excited state. The dyes present low fluorescence quantum yields, which is attributed to radiationless excited state deactivation related to aryl rings rotation. Spectroscopic and electrochemical methods were used to determine the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels. Both optical and electrochemical properties of the TPA-chalcone derivatives are considerably affected by the substitution pattern of the chalcones aryl rings and also by the β-arylation of the olefin moiety.

Novel D–π-A and A–π-D–π-A three-component photoinitiating systems based on carbazole/triphenylamino based chalcones and application in 3D and 4D printing

“…Furthermore, for chalcone 10, two oxidation peaks were observed in the positive potential range, which can be related to a further oxidation (not reversible) event at higher potentials [43]. The obtained LUMO/HOMO energy levels (Highest Occupied Molecular Orbital HOMO and Lowest Unoccupied Molecular Orbital LUMO) are…”

“…Remarkably, very high electron transfer quantum yields (Φet) for chalcone 4 were calculated (Table 3) in agreement with efficient r2 and r3 processes. Compared to chalcone 4, chalcone 7 and 10 showed lower electron transfer quantum yields (ϕet), which can be probably attributed to a radiation-free excited state deactivation related to an aryl rings rotation [27,43]. For the mechanistic investigation, electrochemical reactions of chalcones 4, 7 and 10 were also examined by cyclic voltammetry.…”

“…Considering that carbazoles and triphenylamines are excellent electron donors, the push-pull effect caused by the intramolecular interactions between the donor and the acceptor will lead to a strong charge delocalization all over the molecule, thus inducing the appearance of an intense transition in the visible region [42][43][44].…”

Bis-chalcone derivatives derived from natural products as near-UV/visible light sensitive photoinitiators for 3D/4D printing

“…As shown in Figure S2, a favorable electron transfer reaction occurred in bis-chalcone / iodonium salt: ∆GS1 Iod = -1.67 eV and -0.78 eV for bis-chalcones 5 and 9, respectively (Table 4). Remarkably, two oxidation peaks were observed in the positive potential range of bis-chalcone 5, corresponding to a further oxidation (not reversible) even at higher potentials [50]. In addition, clear reduction peaks were observed as the oxidation reactions, revealing electron transfer reactions also occurred in bis-chalcone / amine (e.g., ∆GS1 EDB = -0.72 eV and -0.41 eV for bis-chalcones 5 and 9 respectively, Table 4).…”

Estudos sintéticos visando à preparação de novas indolizinas aromáticas

“…L -1 , como mencionado, garantindo a solubilização de todas as sondas e prevenindo a formação de agregados. sistema carbonil ,β-insaturado da chalcona, como já relatado para outros sistemas orgânicos π-conjugados contendo grupos doadores e aceptores em suas estruturas (PANNIPARA et al, 2014;COSTA et al, 2019). O efeito batocrômico também foi reportado em estudos anteriores, para as indolizinas 2,5-dissubstituídas, quando grupos fortemente sacadores de elétrons, como o grupo nitro, foram inseridos na estrutura da indolizina (AMARAL et al, 2014), o que foi explicado pela considerável redução da energia LUMO (UENO et al, 2006).…”