Coumarin-Annelated Regioisomeric Heptahelicenes: Influence of Helicity on Excited-State Properties and Chiroptical Properties

Mukhopadhyay, Arindam; Jana, Kanyashree; Hossen, Tousif; Sahu, Kalyanasis; Moorthy, Jarugu Narasimha

doi:10.1021/acs.joc.9b01126

Cited by 13 publications

(12 citation statements)

References 46 publications

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“…A set of analogous helical pyranones exhibited absorption maximum in the range (360–415 nm). [ 8 ] It highlights the importance of linear‐fusion as well as planarity, as in 1 and 2 , in improving the absorption characteristics of coumarins. Interestingly, the absorption maximum of 1 – 2 is not influenced much by the solvent polarity (Figure 1 and Figure S1), which suggests their weak dipolar character, similar to other modified acenes.…”

Section: Methodsmentioning

confidence: 99%

“…For a comparison, their shorter linear analogue, benzo[ g ]coumarin and non‐planar helical coumarins exhibited blue emission at 459 nm and 452–486 nm, respectively. [ 6–8 ] Emission spectrum of 1 and 2 recorded in solvents of varying polarity pointed no obvious change in the emission maximum (Figure S1) indicating a minimal or no drastic change of their dipole moment in the excited state. As coumarins are brilliant fluorophores, the photoluminescence quantum yields (Φ f ) of the new anthra‐fused red‐emissive coumarins 1 and 2 were estimated, and they were 24 and 19 %, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…Gratifyingly, these values are found to be significantly higher than that of simple benzo[ g ]coumarin, helical coumarins, tetracene and pentacene. [ 6,8,18b,22 ]…”

Section: Methodsmentioning

confidence: 99%

“…By appropriately placing the substituents within the molecular structure of benzo[ g ]coumarin, one can in principle achieve a bathochromic shift further down (due to ICT) in the absorption and emission spectra, the property that is key for bioimaging applications. [ 7 ] Inspired by this result, several reports have appeared on the helical, [ 8 ] vertical [ 9 ] and lateral [ 10 ] π‐expansion of coumarins/benzocoumarins, and their photophysical properties have been investigated carefully.…”

Section: Methodsmentioning

confidence: 99%

“…However, linear coumarins, beyond benzo[ g ]coumarins, have not been achieved so far and their optical properties remain yet unexplored. In continuation to our recent efforts on coumarin and its π‐expansion, [ 8c,10,11 ] to build on its chemistry further we have herein targeted the synthesis of novel coumarinacenes (Scheme 1). Coumarinacenes are linearly π‐expanded coumarin analogues.…”

Section: Methodsmentioning

confidence: 99%

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Linear Coumarinacenes Beyond Benzo[g]coumarins: Synthesis and Promising Characteristics

et al. 2020

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New heteroacenes, named coumarinacenes, have been designed, synthesized and characterized. They possess visible absorption and orange-red emission that are far beyond those of benzo[g]coumarins. They exhibit deep HOMO energy levels, and reveal excellent thermal, photochemical and air sta-Coumarins are pyranone-annulated benzenes (2H-benzopyran-2-ones) that are ubiquitous in nature. [1] They are actually popular for their wide spectrum of biological and pharmacological activities, [2a] such as, antioxidant, [2b] antidepressant, [2c] anticoagulant, [2d] anti-inflammatory, [2e] antifungal, [2f ] antitumor, [2g] anti-HIV, [2h] antibiotic, [2i] etc., and for their excellent biocompatibility. [1] Structurally simple derivatives of coumarin exhibit rich photophysical and photochemical properties (high photoluminescence quantum yields, large Stokes shifts and good photostability) paving their entry into modern photonic applications; laser dyes, [3a,3b] non-linear optics, [3c] two-photon bioimaging [3d] and sensing [3e] are some examples. Moreover, coumarin derivatives are recently being exploited as functional materials in organic light emitting devices, [4a,4b] liquid crystals, [4c] dye-sensitized solar cells, [4d,4e] electron and energy transfer systems, [4f,4g] and fluorescent probes. [4h] Despite the broad utility of coumarins, the low-lying absorption and emission wavelengths (due to shorter conjugation lengths) are primarily the bottlenecks in furthering their applications. In an effort to overcome the limitations, considerable attention is devoted in recent times for the development of novel π-expanded coumarin dyes. [5] Benzocoumarins-the simplest π-expanded benzene-fused coumarins-indeed absorb and emit light in the longer wavelength region when compared to parent coumarins (Scheme 1). [6] Among the other isomeric [a] A

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…Gratifyingly, these values are found to be significantly higher than that of simple benzo[ g ]coumarin, helical coumarins, tetracene and pentacene. [ 6,8,18b,22 ]…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Linear Coumarinacenes Beyond Benzo[g]coumarins: Synthesis and Promising Characteristics

et al. 2020

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An Angular Coumarinacene and Its Characteristics

Kumar

Venkatakrishnan

2021

Asian J Org Chem

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This paper describes the synthesis of an angular coumarinacene. Its molecular structure by single-crystal Xray analysis is revealed for the first time, which noted a sandwich-dimeric herringbone arrangement. Its solution reveals visible absorption and bright yellow-orange emission. The pyranone-annulated angular coumarinacene is relatively stable, both thermally and photochemically, when compared to popular acenes. Its alignment of frontier orbital energy levels dictates its possible entry into electronics.Coumarins are widely present in nature. [1] Studies on coumarins have shown enormous potential in biochemical and pharmaceutical regimes; for example, as antidepressants, [2] antimicrobials, [3] antivirals, [4] anticancer, [5] antioxidants, [6] antiinflammatory agents, [7] antitumors [8] and anticoagulants. [9] Besides, these benzo-α-pyranones reveal strong absorption, [10] high fluorescence quantum yields, [11] and excellent photostability. [12] Hence, they act as popular laser dyes, [13] optical brighteners, [14] luminescent materials, [15] and fluorescent probes. [16] As proven bio-friendly, coumarins serve as food additives, [17] flavoring substances, and cosmetic agents. [17,18] Due to these beneficial properties, synthetic interest in coumarins has been growing consistently. Organic chemists devote considerable time and effort in developing novel synthetic methods and approaches to expand coumarin's horizon (Figure 1a). [19] However, the structural elaboration beyond benzo-annulated coumarins have been limited. With the increasing demand for polycyclic aromatic hydrocarbons (PAHs) in organic electronics and photonics, [20] Gryko et al. have developed several vertically π-expanded mono-or bis-coumarins with an aim to improve the optical properties. [19] They demonstrated the use of biscoumarins as organic semiconductors for photocatalytic oxygen reduction reactions. [21] Moorthy et al. constructed small to large helical coumarins, and derived photochromic pyrans [22] as well as chirooptical materials from them. [23] The rich chemistry of coumarins have further paved their entry into various other fields as well. Thus, functionally modified coumarin derivatives have shown promise as watersoluble dyes in bioimaging, [24] emissive materials in organic light-emitting diodes (OLEDs), [25] and strongly absorbing dyes in dye-sensitized solar cells (DSSCs). [26]

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Metal Free Synthesis of Coumarin Containing Hetero[n]helicene like Molecules with TICT and AIE Properties

Soni

Soman

2022

Asian J Org Chem

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Coumarin containing hetero [n]helicene like molecules were synthesized using three component Povarov reaction followed by two dehydrogenation steps in good yields. Synthesis and photophysical properties of coumarin containing multifunctional helicene like molecules were found to be affected by substitution on pendant phenyl ring. Coumarin containing hetero[6]helicene like derivative 10 f showed bright yellow emission in solution, thin film, and solid state. Coumarin containing hetero[6]helicene like compound 13 e showed bright blue emission in solution, thin film, and solid state. The structures of intermediate compounds were confirmed by a single crystal X-ray analysis. These structures were compared with DFT optimized structures for the helicity parameters. DFT calculations provided good correlation with observed photophysical properties of compounds 10 f and 13 e.

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Coumarin-Annelated Regioisomeric Heptahelicenes: Influence of Helicity on Excited-State Properties and Chiroptical Properties

Cited by 13 publications

References 46 publications

Linear Coumarinacenes Beyond Benzo[g]coumarins: Synthesis and Promising Characteristics

Linear Coumarinacenes Beyond Benzo[g]coumarins: Synthesis and Promising Characteristics

An Angular Coumarinacene and Its Characteristics

Metal Free Synthesis of Coumarin Containing Hetero[n]helicene like Molecules with TICT and AIE Properties

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