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1. A Computational Physical Organic Study of a Torque, Lock, and Propagate Approach and Validation with the Synthesis of Configurationally Stable First‐Generation Helically Twisted Acenes

   https://doi.org/10.1002/ejoc.202101533  

   Weber, Jacob_A; Clennan, Edward_L; Arulsamy, Navamoney (April 2022, European Journal of Organic Chemistry)

   Abstract Hybrid polyaromatic hydrocarbons (PAHs) consisting of helicene and acene domains, referred to as [7]heli‐D‐acenes, are introduced as scaffolds to generate enantiopure twisted acenes (heli‐twistacenes) by a torque, lock, and propagate (TLP) approach. Computational methods with and without dispersion corrections were used to explore the structural and electronic features of these PAHs and to explore the possible formation of twistomers that might complicate reaction mixtures. Syntheses of unsubstituted and disubstituted members of the [7]heli‐D‐acene series confirmed the viability of the TLP approach, and together with the computational results, provided proof‐of‐concept of this new approach as a viable means to generate enantiopure twisted‐acenes. The X‐ray structures, absorption, fluorescence, phosphorescence, and CD spectra of these first generation heli‐acenes are compared to the structure and photophysical properties of pentacene and [7]helicene. A high barrier for the enantio‐enriched M enantiomer of 19,24‐dicyano[7]heli‐D‐anthracene verified its configurational stability at room temperature. 

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2. Exciton coupling chirality in helicene-porphyrin conjugates

   https://doi.org/10.1039/D1CC03314J  

   Dhbaibi, Kais; Matozzo, Paola; Abella, Laura; Jean, Marion; Vanthuyne, Nicolas; Autschbach, Jochen; Favereau, Ludovic; Crassous, Jeanne (October 2021, Chemical Communications)

   Enantiopure helicene-porphyrin conjugates were prepared. They show strong changes in their circular dichroic response as compared to classical helicene derivatives, with highly intense bisignate Exciton Coupling (EC) signal and Δ ε values up to 680 M −1 cm −1 for the Soret band. They also display circularly polarized fluorescence in the (far-)red region, with dissymmetry factors up to 7 × 10 −4 . 

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3. Left and Right‐Handed Light Reflection and Emission in Ultrathin Cellulose Nanocrystals Films with Printed Helicity

   https://doi.org/10.1002/adfm.202404857  

   Bukharina, Daria; Southard, Lindsay; Dimitrov, Botyo; Brackenridge, Justin_A; Kang, Saewon; Min, Peng; Wang, Yanan; Nepal, Dhriti; McConney, Michael_E; Bunning, Timothy_J; et al (May 2024, Advanced Functional Materials)

   Abstract Natural polymers, particularly plant‐derived nanocelluloses, self‐organize into hierarchical structures, enabling mechanical robustness, bright iridescence, emission, and polarized light reflection. These biophotonic properties are facilitated by the assembly of individual components during evaporation, such as cellulose nanocrystals (CNCs), which exhibit a left‐handed helical pitch in a chiral nematic state. This work demonstrates how optically active films with pre‐programmed opposite handedness (left or right) can be constructed via shear‐induced twisted printing with clockwise and counter‐clockwise shearing vectors. The resulting large‐area thin films are transparent yet exhibit pre‐determined mirror‐symmetrical optical activity, enabling the distinction of absorbed and emitted circularly polarized light. This processing method allows for sequential printing of thin and ultrathin films with twisted layered organization and on‐demand helicity. The complex light polarization behavior is due to step‐like changes in linear birefringence within each deposited layer and circular birefringence, different from that of conventional CNC films as revealed with Muller matrix analysis. Furthermore, intercalating an achiral organic dye into printed structures induces circularly polarized luminescence while preserving high transmittance and controlled handedness. These results suggest that twisted sequential printing can facilitate the construction of chiroptical metamaterials with tunable circular polarization, absorption, and emission for optical filters, encryption, photonic coatings, and chiral sensors. 

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4. Advanced polarization-control strategies for enhancing performance in multipetawatt laser facilities

   https://doi.org/10.1063/5.0273151  

   Jeon, C.; Black, A_N; Spilatro, M_A; Bahk, S-W; Bromage, J. (August 2025, Physics of Plasmas)

   Our research focuses on designing all-reflective phase retarders (RPRs) to generate and maintain circularly polarized (CP) light for NSF OPAL and other multipetawatt laser facilities. Assuming that the input polarization is either s- or p-polarized, RPRs need to be used in an out-of-plane configuration. Here, we will discuss the impact of transporting and focusing optics on CP light. 

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5. Achieving high circularly polarized luminescence with push–pull helicenic systems: from rationalized design to top-emission CP-OLED applications

   https://doi.org/10.1039/D0SC06895K  

   Dhbaibi, Kais; Abella, Laura; Meunier-Della-Gatta, Sylvia; Roisnel, Thierry; Vanthuyne, Nicolas; Jamoussi, Bassem; Pieters, Grégory; Racine, Benoît; Quesnel, Etienne; Autschbach, Jochen; et al (April 2021, Chemical Science)

   null (Ed.)

   While the development of chiral molecules displaying circularly polarized luminescence (CPL) has received considerable attention, the corresponding CPL intensity, g lum, hardly exceeds 10 −2 at the molecular level owing to the difficulty in optimizing the key parameters governing such a luminescence process. To address this challenge, we report here the synthesis and chiroptical properties of a new family of π-helical push–pull systems based on carbo[6]helicene, where the latter acts as either a chiral electron acceptor or a donor unit. This comprehensive experimental and theoretical investigation shows that the magnitude and relative orientation of the electric ( μe ) and magnetic (μ m ) dipole transition moments can be tuned efficiently with regard to the molecular chiroptical properties, which results in high g lum values, i.e. up to 3–4 × 10 −2 . Our investigations revealed that the optimized mutual orientation of the electric and magnetic dipoles in the excited state is a crucial parameter to achieve intense helicene-mediated exciton coupling, which is a major contributor to the obtained strong CPL. Finally, top-emission CP-OLEDs were fabricated through vapor deposition, which afforded a promising g El of around 8 × 10 −3 . These results bring about further molecular design guidelines to reach high CPL intensity and offer new insights into the development of innovative CP-OLED architectures. 

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