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  1. Free, publicly-accessible full text available April 27, 2023
  2. Free, publicly-accessible full text available March 22, 2023
  3. 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 .
  4. The rationalization of the molecular parameters that influence the intensity and sign of circularly polarized luminescence (CPL) for chiral emitters is a challenging task and remains of high interest for future chiral optoelectronic applications. In this report, we explore the design of novel chiral donor–acceptor structures based on C 2 -symmetric bicarbazole systems and compare the influence of the type of chirality, namely axial versus helical, and the electron withdrawing strength of the acceptor units on the resulting photophysical and CPL properties. By using carbonyl-based acceptors with both axial and helical electron donors, CP-Thermally Activated Delayed Fluoresence (TADF) can be obtained, whose efficiency depends on the dihedral angle between the carbazole moieties, related to the axial and helical chirality of the compounds. The latter also impacts the intensity of the CPL, which shows an opposite trend as a function of the polarity of the solvent, with a notably strong increase of the luminescence dissymmetry factor, g lum , for the helical donor–acceptor compounds related to a subtle reoarganization of the intramolecular charge-transfer process.
  5. The sodium anion (Na − ) was once thought to behave like a ‘genuine’ anion, with both the [Ne] core and the 3s valence shell interacting very weakly with their environments. In the present work, following a recent study of the surprisingly small quadrupolar line widths of Na − , NMR shielding calculations were carried out for the Na − /Na + [2.2.2]cryptand system solvated in methylamine, based on ab initio molecular dynamics simulations, followed by detailed analyses of the shielding constants. The results confirm that Na − does not act like a quasi-free ion that interacts only weakly with its surroundings. Rather, the filled 3s shell of Na − interacts strongly with its chemical environment, but only weakly with the ion's own core and the nucleus, and it isolates the core from the chemical environment. As a consequence, the Na − ion appears in NMR experiments like a free ion.
  6. 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 guidelinesmore »to reach high CPL intensity and offer new insights into the development of innovative CP-OLED architectures.« less