A Beneficial Effect of Bromination on the Photophysical and Photochemical Properties of Aza‐BODIPY Dyes with Electron‐Donating Groups

Obłoza, Magdalena; Łapok, Łukasz; Pędziński, Tomasz; Nowakowska, Maria

doi:10.1002/ajoc.201900385

Cited by 10 publications

(9 citation statements)

References 56 publications

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“…Upon gradually increasing the amount of trifluoroacetic acid (TFA) in diluted dichloromethane solution, the absorption maximum (λ max = 738 nm, ε = 57 000 M –1 cm –1 , ω 1/2 = 2800 cm –1 ) undergoes a significant blue shift accompanied by a noticeable hyperchromic effect and a decrease of the linewidth (λ max = 680 nm, ε = 87,000 M –1 cm –1 , ω 1/2 = 1400 cm –1 ), with the presence of one isobestic point (Figure ). Evidently, the protonation of the dihexylamino auxochromes to form ammonium groups suppresses their electron-donating character and consequently inhibits the charge-transfer transition. − The shape of the absorption of the protonated form is very similar to the absorption spectrum of 2 b featuring electron-withdrawing nitrofluorenylethynyl substituents.…”

Section: Results and Discussionmentioning

confidence: 95%

Unraveling the Two-Photon and Excited-State Absorptions of Aza-BODIPY Dyes for Optical Power Limiting in the SWIR Band

et al. 2019

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We describe the linear and nonlinear optical properties of substituted aza-boron-dipyrromethene (aza-BODIPY) dyes with a focus on the impact of the spatial position and electronic nature of the substituents. The experimental findings are rationalized through Time-Dependent Density Functional Theory calculations, pointing out the crucial importance of intramolecular charge transfer to achieve strong two-photon absorption in the near-infrared, with measured cross-sections up to 3300 GM at ca. 1200 nm and 1110 GM at telecommunication wavelengths (1500 nm). The evaluation of the optical power limiting behavior of the series highlights that a [2+1] process, i.e. two-photon absorption followed by excited state absorption, was necessary for high optical power limiting efficiencies. Tetrafunctionalized aza-BODIPY, featuring an optimized overlap between two-photon absorption and excited state absorption in the 1200-1600 nm range stands as an ideal platform to obtain efficient broad range optical limiter.

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Section: Results and Discussionmentioning

confidence: 95%

Unraveling the Two-Photon and Excited-State Absorptions of Aza-BODIPY Dyes for Optical Power Limiting in the SWIR Band

et al. 2019

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“…Given the very strong electron‐donating character of the p ‐(Ph 2 N)Ph− substituted aza‐BODIPY/ADPM described in this paper combined with high thermal stability, remarkable photostability, high molar absorption coefficient ( ϵ ) and low ionization potential, we postulate that these compounds maybe of great interest as photoactive/electroactive components of various organic electronics or optoelectronics. In Figure we compared a set of aza‐BODIPYs and aza‐dipyrromethenes with both electron‐donating and electron‐accepting groups prepared and reported by our research group …”

Section: Resultsmentioning

confidence: 99%

“… A comparison of optical ( λ abs , in THF) and electrochemical ( E ox 1 , E red 1 in 1,2‐dichlorobenzene or THF) properties of aza‐dipyrromethenes and aza‐BODIPYs bearing either electron‐withdrawing or electron‐donating substituents at 5,5′ positions (aza‐dipyrromethene) or 3,5 positions (aza‐BODIPY) prepared in our laboratory …”

Section: Resultsmentioning

confidence: 99%

“…Our interest in efficient yet stable organic triplet photosensitizes capable of light absorption from the visible and near‐IR part of the spectrum has lead us to the discovery of novel aza‐BODIPYs . Herein, we report the five‐steps synthesis and a comprehensive study on the photophysical and electrochemical properties of aza‐BODIPY substituted with strongly electron‐donating p ‐(diphenylamino)phenyl substituents ( p ‐Ph 2 N) at 3,5‐positions (see Scheme ).…”

Section: Introductionmentioning

confidence: 99%

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Near‐Infrared Photoactive Aza‐BODIPY: Thermally Robust and Photostable Photosensitizer and Efficient Electron Donor

et al. 2020

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We report herein the synthesis of aza-BODIPY substituted with strongly electron-donating p-(diphenylamino)phenyl substituents (p-Ph 2 NÀ ) at 3,5-positions. The presence of p-Ph 2 NÀ groups lowers the energy of the singlet excited state (E s ) to 1.48 eV and induces NIR absorption with λ abs at 789 nm in THF. The compound studied is weakly emissive with the emission band (λ f ) at 837 nm and with the singlet lifetime (τ S ) equal to 100 ps. Nanosecond laser photolysis experiments of the aza-BODIPY in question revealed T 1 !T n absorption spanning from ca. 350-550 nm with the triplet lifetime (τ T ) equal to 21 μs. By introducing a heavy atom (Br) into the structure of the aza-BODIPY, we managed to turn it into a NIR operating photosensitizer. The photosensitized oxygenation of the model compound-diphenylisobenzofuran (DPBF)-proceedes via Type I and/or Type III mechanism without formation of singlet oxygen ( 1 O 2 ). As estimated by CV/DPV measurements, the p-Ph 2 NÀ substituted aza-BODIPYs studied exhibits oxidation processes at relatively low oxidation potentials (E ox 1 ), pointing to the very good electron-donating properties of these molecules. Extremely high photostability and thermal robustness up to approximately 300°C are observed for the p-Ph 2 NÀ substituted aza-BODIPYs. [a] Dr. . Synthesis of mono-bromo aza-BODIPY 7. Reaction conditions: a) acetyl chloride, ZnCl 2 , DCM, 0°C to reflux, 24 h, 45 %; b) 4-tert-butylbenzaldehyde, NaOH, EtOH, 0°C to RT, 24 h, 69 %; c) MeNO 2 , K 2 CO 3 , MeOH, reflux, 17 h, 79 % ; d) CH 3 COONH 4 ,n-butanol, 117°C, 3 h, 63 %; e) BF 3 · Et 2 O, DIPA, DCM, 1 h, 91 %; f) NBS, DCM, 2 h, 0°C, 96 %.ChemPhysChem Articles

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“…The photophysical features of BODIPY 5 , 23 , 26 , 27 and aza-BODIPY 28 − 33 dye classes have been extensively studied individually; conversely, there is almost no simultaneous comparison of BODIPY and aza-BODIPY structural analogues. 18 , 19 Since aza-BODIPYs are a subclass to BODIPY dyes, it seems intriguing that these classes have, to our knowledge, not yet been accurately compared.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Aza-N-Bridge and Push–Pull Moieties: A Comparative Study between BODIPYs and Aza-BODIPYs

et al. 2022

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In the field of fluorescent dyes, difluoroboron-dipyrromethenes (BODIPY) have a highly respected position. To predict their photophysical properties prior to synthesis and therefore to successfully design molecules specifically for one’s needs, a solid structure–function understanding based on experimental observations is vital. This work delivers a photophysical evaluation of BODIPY and aza-BODIPY derivatives equipped with different electron-withdrawing/-donating substituents. Using combinatorial chemistry, pyrroles substituted with electron-donating/-withdrawing substituents were condensed together in two different manners, thus providing two sets of molecules. The only difference between the two sets is the bridging unit providing a so far lacking comparison between BODIPYs and aza-BODIPYs structural homologues. Replacing the meso -methine bridge with an aza-N bridge results in a red-shifted transition and considerably different, temperature-activated, excited-state relaxation pathways. The effect of electron-donating units on the absorption but not emission for BODIPYs was suppressed compared to aza-BODIPYs. This result could be evident in a substitution pattern-dependent Stokes shift. The outlook of this study is a deeper understanding of the structure–optics relationship of the (aza)-BODIPY-dye class, leading to an improvement in the de novo design of tailor-made molecules for future applications.

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A Beneficial Effect of Bromination on the Photophysical and Photochemical Properties of Aza‐BODIPY Dyes with Electron‐Donating Groups

Cited by 10 publications

References 56 publications

Unraveling the Two-Photon and Excited-State Absorptions of Aza-BODIPY Dyes for Optical Power Limiting in the SWIR Band

Unraveling the Two-Photon and Excited-State Absorptions of Aza-BODIPY Dyes for Optical Power Limiting in the SWIR Band

Near‐Infrared Photoactive Aza‐BODIPY: Thermally Robust and Photostable Photosensitizer and Efficient Electron Donor

Effect of the Aza-N-Bridge and Push–Pull Moieties: A Comparative Study between BODIPYs and Aza-BODIPYs

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