Helicenes combine two central themes in chemistry: extended π-conjugation and chirality. Heteroatom doping preserves both characteristics and allows to modulate the electronic structure of a helicene. Herein, we report the (BO)2-doped tetrathia[7]helicene 1, which was prepared from 2-methoxy-3,3'-bithiophene via four steps. 1 is formally derived by substituting two (Mes)B-O moieties in place of (H)C=C(H) fragments in two benzene rings of parent tetrathia[7]helicene. X-ray crystallography revealed a dihedral angle of 50.26(9)° between the two terminal thiophene rings. (P)-/(M)-1 enantiomers were separated by chiral-HPLC and are configurationally stable at room temperature. The experimentally determined enantiomerization barrier of 27.4 ± 0.1 kcal mol-1 is lower than that of tetrathia[7]helicene (39.4 ± 0.1 kcal mol-1). Circular dichroism spectra of (P)- and (M)-1 show a perfect mirror-image relationship. 1 is a blue emitter (λem = 411 nm) with a photoluminescence quantum efficiency of ΦPL = 6% (cf. tetrathia[7]helicene: λem ≈ 405 nm, ΦPL = 5%).

(BO)2-Doped Tetrathia[7]helicene: A Configurationally Stable Blue Emitter / L. Menduti, C. Baldoli, S. Manetto, M. Bolte, H. Lerner, G. Longhi, C. Villani, E. Licandro, M. Wagner. - In: ANGEWANDTE CHEMIE. INTERNATIONAL EDITION. - ISSN 1433-7851. - (2022), pp. 1-8. [Epub ahead of print] [10.1002/anie.202215468]

(BO)2-Doped Tetrathia[7]helicene: A Configurationally Stable Blue Emitter

L. Menduti;E. Licandro
Penultimo
;
2022

Abstract

Helicenes combine two central themes in chemistry: extended π-conjugation and chirality. Heteroatom doping preserves both characteristics and allows to modulate the electronic structure of a helicene. Herein, we report the (BO)2-doped tetrathia[7]helicene 1, which was prepared from 2-methoxy-3,3'-bithiophene via four steps. 1 is formally derived by substituting two (Mes)B-O moieties in place of (H)C=C(H) fragments in two benzene rings of parent tetrathia[7]helicene. X-ray crystallography revealed a dihedral angle of 50.26(9)° between the two terminal thiophene rings. (P)-/(M)-1 enantiomers were separated by chiral-HPLC and are configurationally stable at room temperature. The experimentally determined enantiomerization barrier of 27.4 ± 0.1 kcal mol-1 is lower than that of tetrathia[7]helicene (39.4 ± 0.1 kcal mol-1). Circular dichroism spectra of (P)- and (M)-1 show a perfect mirror-image relationship. 1 is a blue emitter (λem = 411 nm) with a photoluminescence quantum efficiency of ΦPL = 6% (cf. tetrathia[7]helicene: λem ≈ 405 nm, ΦPL = 5%).
Chirality; Helicenes; boron; doping; thiophenes;
Settore CHIM/06 - Chimica Organica
21-nov-2022
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/946657
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