Circularly polarized luminescence of helicenes: A data‐informed insight

Chirality, Journal Year: 2023, Volume and Issue: 35(4), P. 192 - 210

Published: Jan. 27, 2023

Abstract Helicenes are an interesting scaffold for chiroptical properties and in particular circularly polarized luminescence (CPL). In this short review, we collect the (g lum ) absorption abs dissymmetry factors associated to first Cotton effect of electronic circular dichroism (ECD) spectrum. Considering data 170 [n]‐helicenes ( n = 4–11), overall found reasonable correlations between g . Despite a few notable exceptions, would confirm similarity stereochemistry ground emitting excited states most helicenes. These results may be useful rationalizing help chemists designing new helicene structures with desired CPL properties.

Language: Английский

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Catalytic Enantioselective Synthesis of Helicenes

Chemistry - A European Journal, Journal Year: 2022, Volume and Issue: 28(68)

Published: Sept. 5, 2022

Helicenes and helicene-like molecules, usually containing multiple ortho-fused aromatic rings, possess unique helical chirality. These compounds have found a wide range of important applications in many research fields, such as asymmetric catalysis, molecular recognition, sensors responsive switches, circularly polarized luminescence materials others. However, the catalytic enantioselective synthesis helicenes was largely underexplored, when compared with molecules bearing other stereogenic elements (e.g. central chirality axial chirality). Since pioneer work via [2+2+2] cycloaddition triynes by Stará Starý, last two decades witnessed tremendous development helicenes. In this review, we comprehensively summarized advances field, which include methods enabled both transition metal catalysis organocatalysis, provide our perspective on its future development.

Language: Английский

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Enantioselective synthesis of [4]helicenes by organocatalyzed intermolecular C-H amination

Nature Communications, Journal Year: 2024, Volume and Issue: 15(1)

Published: Jan. 25, 2024

Abstract Catalytic asymmetric synthesis of helically chiral molecules has remained an outstanding challenge and witnessed fairly limited progress in the past decades. Current methods to construct such compounds almost entirely rely on catalytic enantiocontrolled fused-ring system extension. Herein, we report a direct terminal peri -functionalization strategy, which allows for efficient assembling 1,12-disubstituted [4]carbohelicenes via organocatalyzed enantioselective amination reaction 2-hydroxybenzo[ c ]phenanthrene derivates with diazodicarboxamides. The key feature this approach is that stereochemical information catalyst could be transferred into not only helix sense but also remote C-N axial chirality products, thus enabling [4]- [5]helicenes both structural diversity complexity good efficiency excellent enantiocontrol. Besides, large-scale preparations representative transformations helical products further demonstrate practicality protocol. Moreover, DFT calculations reveal hydrogen bonds C-H---π interactions between substrates contribute ideal control.

Language: Английский

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Synthesis of Aza[n]helicenes up to n = 19: Hydrogen-Bond-Assisted Solubility and Benzannulation Strategy

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(25), P. 17428 - 17437

Published: June 12, 2024

Synthetic challenges toward anomalous structures and electronic states often involve handling problems such as insolubility in common organic solvents oxidative degradation under aerobic conditions. We designed benzo-annulated aza[n]helicenes, which benefit from both the suppressed elevation of highest occupied molecular orbital (HOMO) energies high solubility due to hydrogen bonding with solvent molecules overcome these challenges. This strategy enabled synthesis six new aza[n]helicenes ([n]AHs) different lengths (n = 9–19) acyclic precursors via one-pot intramolecular fusion reactions. The all synthesized were determined by X-ray diffraction (XRD) analysis, their electrochemical potentials measured cyclic voltammetry. Among [17]AH [19]AH are first heterohelicenes a triple-layered helix. noncovalent interaction (NCI) plots confirm existence an effective π–π between layers. absorption fluorescence spectra red-shifted helical increased, without any distinct saturation points. optical resolutions N-butylated [9]AH, [11]AH, [13]AH, [15]AH accomplished, circular dichroism (CD) circularly polarized luminescence (CPL) measured. Thus, structural, (chir)optical, properties comprehensively analyzed.

Language: Английский

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Enantiopure synthesis of [5]helicene based molecular lemniscates and their use in chiroptical materials

Nature Communications, Journal Year: 2025, Volume and Issue: 16(1)

Published: March 22, 2025

Abstract The ability to synthesise lemniscular molecules allow for the study and application of their chiroptical properties is a notable technical challenge. Herein, we report design synthesis enantiomers [5]helicenoid derived molecular lemniscate, in which two homochiral helicenes are linked via formation azine motifs. We demonstrate that these molecules, helicenoid constituents, also excellent chiral dopants induce dissymmetry ground excited states achiral emissive polymer F8BT, leading high CPL activity. control handedness enantiopure affords sign CP emission. This manipulation circularly polarised light great interest optoelectronic technologies.

Language: Английский

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Sulfur(IV) in Transition-Metal-Free Cross-Couplings for Biaryl Synthesis

ACS Sustainable Chemistry & Engineering, Journal Year: 2022, Volume and Issue: 10(8), P. 2569 - 2586

Published: Feb. 16, 2022

The reactivity of sulfur(IV) compounds is great current interest among organic chemists. In this Perspective, we discuss the chemistry (namely, sulfoxides, sulfonium salts, and sulfinates) within area transition-metal-free cross-couplings for biaryl synthesis. These sulfur(IV)-based methods show potential in sustainable formation can deliver unique structures that are difficult to access by other means. This Perspective also highlights how versatile has helped design new reagents, mediators, catalysts.

Language: Английский

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Enhanced Optical Properties of Azaborole Helicenes by Lateral and Helical Extension

Chemistry - A European Journal, Journal Year: 2022, Volume and Issue: 28(62)

Published: July 25, 2022

The synthesis and characterization of laterally extended azabora[5]-, -[6]- -[7]helicenes, assembled from N-heteroaromatic dibenzo[g,p]chrysene building blocks is described. Formally, the π-conjugated systems pristine azaborole helicenes were enlarged with a phenanthrene unit leading to compounds large Stokes shifts, significantly enhanced luminescence quantum yields (Φ) dissymmetry factors (glum ). beneficial effect on optical properties was also observed for helical elongation. combined contributions lateral extensions resulted in compound showing green emission Φ 0.31 |glum | 2.2×10-3 , highest within series π-extended azaborahelicenes superior intensity chiroptical response its non-extended congener. This study shows that are viable strategies improve features helicenes. In addition, single crystal X-ray analysis configurationally stable [6]- -[7]helicenes used provide insight into their packing arrangements.

Language: Английский

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Highly Fluorescent Bipyrrole‐Based Tetra‐BF₂ Flag‐Hinge Chromophores: Achieving Multicolor and Circularly Polarized Luminescence

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(27)

Published: May 5, 2022

This study reports the facile syntheses of tetra-boron difluoride (tetra-BF2 ) complexes, flag-hinge-like molecules that exhibit intense green-to-orange luminescence in solution and yellow-to-red emission solid states. Single-crystal structure analysis density functional theory calculations suggested a bent this series compounds. The complexes also exhibited excellent optical properties, with quantum yields reaching 100 % large Stokes shift. These properties were attributed to altered bending angle molecule S1 excited state. As rotational motion was suppressed around 2,2'-bipyrrole axis, atropisomers axial chirality formed, which are optically resolvable into (R) (S)-enantiomers through chiral column. thus function as circularly polarized luminescent (CPL) materials, color (green, green-yellow, yellow) can be varied by controlling aggregation rational design multi-BF2 potentially realize novel photofunctional materials.

Language: Английский

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Palladium-Catalyzed Modular Synthesis of Enantioenriched Pyridohelicenes through Double Imidoylative Cyclization

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(20), P. 13034 - 13041

Published: Oct. 12, 2022

Enantioenriched pyrido[6]helicenes and furan-containing pyrido[7]helicenes have been synthesized through palladium-catalyzed double imidoylative cyclization by applying axially achiral multiaryl bisisocyanides aryl iodides as coupling components. Two pyridyl rings were constructed sequentially forming four C–C bonds in one pot with low catalyst loading. A control study using precyclized biaryl monoisocyanides revealed the second pyridine-forming enantiomer-generating step, which also enabled introduction of different substituents, including trifluoromethyl, on helical skeleton. This general convergent approach to structurally diversified optically pure pyridohelicenes paves way for optical studies potential applications this important class azahelicenes.

Language: Английский

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Alcoholysis of oxyphenylene-based super engineering plastics mediated by readily available bases

Polymer Journal, Journal Year: 2024, Volume and Issue: 56(4), P. 369 - 377

Published: Jan. 4, 2024

Language: Английский

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