Effects of chalcogen atom variation in chalcogenadiazole fused indolo[2,3-<i>a</i>]carbazoles

Ghosh, Sirina; Kumar, Neha Rani; Zade, Sanjio S.

doi:10.1039/c7nj04661h

Cited by 8 publications

(5 citation statements)

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“…[ 17,18 ] We have recently reported structure‐property relationship in oxadiazole‐, thiadiazole‐, and selenadiazole‐fused ICs. [ 19 ] Analogous di(furo/thieno/seleno‐pyrrolo)‐benzothiadiazole, [ 15,20–24 ] benzoselenadiazole, [ 20 ] and benzotriazole [ 25,26 ] have been synthesized using Cadogan cyclization [ 27 ] as a key step and incorporated into the conjugated copolymers, dyes, ladder conjugated polymers, [ 28 ] and non‐fullerene acceptors for organic photovoltaics. [ 29 ]…”

Section: Introductionmentioning

confidence: 99%

Triazole‐fused indolo[2,3‐a]carbazoles: synthesis, structures, and properties

Ghosh

Das

Kumar

et al. 2020

Journal of Heterocyclic Chem

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The synthesis, structure, and photophysical and electrochemical properties of triazole fused indolo[2,3‐a]carbazole derivatives 2‐5 are reported. The key step involved in the synthesis of triazole fused indolo[2,3‐a]carbazole derivatives is the Cadogan ring closing reaction. 2‐Hexyl‐5,6‐dinitro‐2H‐benzo[d][1,2,3]triazoles having 4,7‐diaryl capping were subjected to the Cadogan cyclization reaction to obtain compounds 2‐5. In contrast to thiadiazole‐fused indolo[2,3‐a]carbazole 1, bromination of triazole‐fused indolo[2,3‐a]carbazole 4 afforded only meta‐dibrominated product with respect to the nitrogen of fused pyrrole rings on treatment with both N‐bromosuccinimide (NBS) and elemental bromine. These compounds showed positive solvatochromism in their emission spectra. Incorporation of electron‐donating substituent in the indole moiety resulted in the elevation of the highest occupied molecular orbital (HOMO) level. Density functional theory (DFT) calculations were performed to support the experimental findings.

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Section: Introductionmentioning

confidence: 99%

Triazole‐fused indolo[2,3‐a]carbazoles: synthesis, structures, and properties

Ghosh

Das

Kumar

et al. 2020

Journal of Heterocyclic Chem

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“…Further, these Cadogan products were bisalkylated by treatment with DMF/NaOH and n‐butyl bromide to get compounds 13 a – c . This variety of chalcogens was found to show an efficient change in structural, optical as well as electrochemical properties [25] . The results revealed that 13 b was a better electron acceptor than 13 a and 13 c indicating the importance of oxygen with high electron affinity.…”

Section: Synthesis Of Chemical Frameworkmentioning

confidence: 94%

“…This variety of chalcogens was found to show an efficient change in structural, optical as well as electrochemical properties. [25] The results revealed that 13 b was a better electron acceptor than 13 a and 13 c indicating the importance of oxygen with high electron affinity. Furthermore, these experimental findings were supported by DFT calculations.…”

Section: Formation Of Carbazole Moietymentioning

confidence: 95%

“…[18d,24] In 2018, Sirina Ghosh and team prepared various chalcogenadiazole fused indolo[2,3-a]carbazoles through Cadogan cyclization as one of the key synthetic steps comprising the variety of chalcogen atoms such as sulphur, oxygen and selenium as shown in Scheme 3. [25] Here, the Cadogan reaction was carried out in the presence of PPh 3 in o-dichlorobenzene (o-DCB) solvent under reflux conditions to afford 12 a-c in moderate yields (36-48%). Further, these Cadogan products were bisalkylated by treatment with DMF/NaOH and n-butyl bromide to get compounds 13 a-c.…”

Section: Formation Of Carbazole Moietymentioning

confidence: 99%

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A Minireview on the Scope of Cadogan Cyclization Reactions Leading to Diverse Azaheterocycles

Kaur

Kumar

2022

Asian J Org Chem

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From the last two decades, Cadogan cyclization reaction is considered as one of the best routes for the preparation of various azaheterocycles comprising carbazoles, indoles, coumarins, carbolines, pyrazoloquinoxalines, S,N‐heterotetracenes from the nitro‐based substrates by using a variety of tetravalent phosphorus‐based reagents. To date the majority of Cadogan reactions are found to be intramolecular reactions, however, interestingly, a case of intermolecular Cadogan reaction is also reported, resulting in the widening of the reaction scope for futuristic perspectives. We report the Cadogan cyclization reactions for the synthesis of azaheterocycles from 2018 to present according to multiple classes of chemical frameworks including its scope (FDA approved drugs), along with the possibilities and mechanistic developments for unexpected products.

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“…and benzothiadiazole (Frizon et al, 2016). This change to more positive values, obtained due to the addition of a heavier chalcogen atom to the heterocycle, can be attributed to an increase in the electronegativity of the chalcogens and proved to be a relevant factor in determining the energies of HOMO and LUMO (Kawashima et al, 2015;Ghosh et al, 2018).…”

Section: Electrochemical Characterizationmentioning

confidence: 95%

Synthesis of 2,1,3-Benzoxadiazole Derivatives as New Fluorophores—Combined Experimental, Optical, Electro, and Theoretical Study

et al. 2020

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Herein, we report the synthesis and characterization of fluorophores containing a 2,1,3-benzoxadiazole unit associated with a π-conjugated system (D-π-A-π-D). These new fluorophores in solution exhibited an absorption maximum at around ∼419 nm (visible region), as expected for electronic transitions of the π-π * type (ε ∼2.7 × 10 7 L mol −1 cm −1), and strong solvent-dependent fluorescence emission (Φ FL ∼0.5) located in the bluish-green region. The Stokes' shift of these compounds is ca. 3,779 cm −1 , which was attributed to an intramolecular charge transfer (ICT) state. In CHCl 3 solution, the compounds exhibited longer and shorter lifetimes, which was attributed to the emission of monomeric and aggregated molecules, respectively. Density functional theory was used to model the electronic structure of the compounds 9a-d in their excited and ground electronic states. The simulated emission spectra are consistent with the experimental results, with different solvents leading to a shift in the emission peak and the attribution of a π-π * state with the characteristics of a charge transfer excitation. The thermal properties were analyzed by thermogravimetric analysis, and a high maximum degradation rate occurred at around 300 • C. Electrochemical studies were also performed in order to determine the band gaps of the molecules. The electrochemical band gaps (2.48-2.70 eV) showed strong correlations with the optical band gaps (2.64-2.67 eV).

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Effects of chalcogen atom variation in chalcogenadiazole fused indolo[2,3-a]carbazoles

Abstract: The chalcogen (O/S/Se)-induced intriguing variation of structural and optoelectronic properties in a series of chalcogenadiazole-fused indolo[2,3-a]carbazole donor–acceptor (D–A) molecules.

Cited by 8 publications

References 37 publications

Triazole‐fused indolo[2,3‐a]carbazoles: synthesis, structures, and properties

Triazole‐fused indolo[2,3‐a]carbazoles: synthesis, structures, and properties

A Minireview on the Scope of Cadogan Cyclization Reactions Leading to Diverse Azaheterocycles

Synthesis of 2,1,3-Benzoxadiazole Derivatives as New Fluorophores—Combined Experimental, Optical, Electro, and Theoretical Study

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