Aggregation-induced emission enhancement in halochalcones

Vaz, Patrícia A. A. M.; Rocha, João; Silva, Artur M. S.; Guieu, Samuel

doi:10.1039/c6nj01387b

Cited by 23 publications

(12 citation statements)

References 30 publications

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“…3‐Chloro‐4‐(dimethylamino)benzaldehyde (2t) : Tan solid, M.p. 72–73 °C; 1 H NMR (360 MHz, CDCl 3 ) δ = 2.98 (6H, s), 7.08 (1H, d, J = 9.8 Hz), 6.70 (1H, dd, J = 9.8 Hz, J = 3.6 Hz), 7.85 (1H, d, J = 3.6 Hz), 9.82 (1H, s); isolated yield: 480 mg (78 %) from 500 mg of 1t .…”

Section: Methodsmentioning

confidence: 99%

In situ Generation of Hypervalent Iodine Reagents for the Electrophilic Chlorination of Arenes

et al. 2019

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Efficient metal‐free methods for the electrophilic chlorination of arenes using PIFA and simple chlorine sources are reported. The in situ formation of PhI(Cl)OCOCF3 from PIFA and KCl is proposed, which resulted in a chlorinating species for moderately activated arenes. Moreover, the in situ formation of PhICl2 from PIFA and TMSCl resulted in an excellent approach for the chlorination of a great variety of arenes (20 examples) in high yields, even when working on a multigram scale.

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Section: Methodsmentioning

confidence: 99%

In situ Generation of Hypervalent Iodine Reagents for the Electrophilic Chlorination of Arenes

et al. 2019

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“…It is worth to note, that only five examples of crystal structures with molecules containing 3-halo-4-dimethylamine substituted phenyl ring were found in Cambridge Structural Database (CSD Version 5.40, 2019) with the following reference codes: TENQEK, ITARUS, LASQOO, LASTUX and LASVAF. [51][52][53][54] In all these structures the configuration of Me 2 NÀ group was pyramidal. The best illustration of Me 2 NÀ different behavior in the molecules 7 and 8 is LASVAF having 4-dimethylamine substituent co-planar with the benzene ring on one side of the molecule and 3-bromo-4-dimethylamine-benzene moiety with the pyramidal configuration of the N atom at the other end of the molecule.…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

Synthesis, Photophysics and Redox Properties of Aza‐BODIPY Dyes with Electron‐Donating Groups

et al. 2019

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A series of novel aza‐BODIPY dyes substituted with p‐(dimethylamino)phenyl groups were synthesized and their spectral and electrochemical properties were compared. In particular, the impact of p‐(Me2N)Ph‐ groups on these characteristics was of consideration. For two aza‐BODIPYs studied, a near‐IR absorption band was observed at circa λabs=796 nm. Due to the pronounced intramolecular charge transfer (ICT) exerted by the presence of strongly electron‐donating p‐(Me2N)Ph‐ substituents, the compounds studied were weakly emissive with the singlet lifetimes (τS) in the picosecond range. Nanosecond laser photolysis experiments of the brominated aza‐BODIPYs revealed T1→Tn absorption spanning from ca. 350 nm to ca. 550 nm with the triplet lifetimes (τT) ranged between 6.0 μs and 8.5 μs. The optical properties of the aza‐BODIPYs studied were pH‐sensitive. Upon protonation of the dimethylamino groups with trifluoroacetic acid in toluene, a stepwise disappearance of the NIR absorption band at λabs=790 nm was observed with the concomitant appearance of a blue‐shifted absorption band at λabs=652 nm, which was accompanied by a prominent emission band at λfl=680 nm. The transformation from a non‐emissive to an emissive compound is associated with the inhibition of the ICT. As estimated by CV/DPV measurements, all aza‐BODIPYs studied exhibited two irreversible oxidation and two quasi‐reversible reduction processes. All compounds studied exhibit extremely high photostability and thermal stability.

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“…Organic luminescent chromophores are known to be very sensitive to their surroundings, often presenting different colors depending on the solvent, [1] the pH, [2] the temperature [3] and their physical state. [4][5][6] They are also sensitive to small modifications, and a change in their structures can have dramatic effect on their photophysical properties. [7][8][9] Based on these characteristics, the emission wavelength of an organic fluorophore can usually be easily fine-tuned, and advantages can be taken of their sensing properties to develop molecular probes, [10] sensors and luminescent devices.…”

Section: Introductionmentioning

confidence: 99%

“…[15] Heteroaromatic chromophores bearing twisted aromatic substituents have emerged as promising candidates for deep blue emission, [15,16] sometimes through thermally activated delayed fluorescence. [17] This goal is difficult to reach, because fluorophores bearing aromatic substituents which can rotate freely often present very small quantum yields in solution, due to non-radiative relaxation, and only emit when those rotations are restricted, for example in aggregate [4,13,18,19] or crystalline state, [5] or when they interact with macromolecules. [12] This general behavior is named aggregation-induced emission enhancement (AIEE), [20] and has been widely studied and applied to biological imaging [12,21,22] and luminescent devices.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Unsymmetrical 2,4,6‐Triarylpyridines as Versatile Scaffolds for Deep‐Blue and Dual‐Emission Fluorophores

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Silva

et al. 2020

ChemPhotoChem

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Pyridines substituted with different aromatic groups at C-2, C-4 and C-6 were prepared following a Kröhnke synthetic route. Introducing ortho-anisole at C-2 resulted in deep blue emitters in solution, with quantum yields up to 74 %. On the other hand, when ortho-phenol was introduced, forming a strong hydrogen bond with the pyridine nitrogen, excited-state intramolecular proton transfer was witnessed by the dual emission of the fluorophores, which is sensitive to the dye environment. The phenyl ring at C-4 was used to introduce electron-donating or withdrawing groups, to fine-tune the photophysical properties of the dyes. Crystal structures of the fluorophores, together with theoretical studies using DFT/TD-DFT calculations, were used to rationalize the experimental photophysical properties of the two families of dyes. Unsymmetrical 2,4,6-triarylpyridines are therefore versatile scaffolds for the preparation of deepblue and dual emission fluorophores, and are promising building blocks for luminescent devices and sensors.

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Aggregation-induced emission enhancement in halochalcones

Abstract: Decorating the periphery of chalcones with halogen atoms increased their aggregation-induced emission enhancement properties, even if their optoelectronic properties are dominated by the other substituents.

Cited by 23 publications

References 30 publications

In situ Generation of Hypervalent Iodine Reagents for the Electrophilic Chlorination of Arenes

In situ Generation of Hypervalent Iodine Reagents for the Electrophilic Chlorination of Arenes

Synthesis, Photophysics and Redox Properties of Aza‐BODIPY Dyes with Electron‐Donating Groups

Unsymmetrical 2,4,6‐Triarylpyridines as Versatile Scaffolds for Deep‐Blue and Dual‐Emission Fluorophores

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