Dithia[9]helicenes: Molecular design, surface imaging, and circularly polarized luminescence with enhanced dissymmetry factors

Bianca C. Baciu (1, 2) , Pawel J. Bronk (1, 2) , Tamara de Ara (1, 2) , Rafael Rodriguez (3) , Pierpaolo Morgante (4) , Nicolas Vanthuyne (5) , Carlos Sabater (1, 2) , Carlos Untiedt (1, 2) , Jochen Autschbach (4) , Jeanne Crassous (3) , Albert Guijarro (1, 2)

1 Universidad de Alicante
2 CSIC - Consejo Superior de Investigaciones Científicas [Spain]
3 ISCR - Institut des Sciences Chimiques de Rennes
4 State University of New York [Buffalo]
5 ISM2 - Institut des Sciences Moléculaires de Marseille

Synthesis of two dithia[9]helicenes by means of a LED-based double photocyclization is reported. The compounds have sulfur atoms placed at the terminal rings of the helicene, and they display two alternative C-2-symmetrical arrangements named exo (1) and endo (2). Separation of enantiomers of opposite helicity allowed the complete characterization in solution, in silico, by X-ray crystallography, and adsorbed on gold. The theoretical analysis confirms the unexpected finding that endodithia[9]heEicene displays an experimental dissymmetry factor (g(lum)) in CPL larger than its isomer exodithia[9]heEicene (-0.0125 vs. -0.0042). This enhanced g(lum) factor ranks among the largest for a helicene-type molecule. Comparison with smaller analogues, namely exo and endo-dithia[7]helicenes (10 and 11, respectively), is also presented.

Domaines: Chimie

Bianca C. Baciu, Pawel J. Bronk, Tamara de Ara, Rafael Rodriguez, Pierpaolo Morgante, et al.. Dithia[9]helicenes: Molecular design, surface imaging, and circularly polarized luminescence with enhanced dissymmetry factors. Journal of Materials Chemistry C, 2022, 10 (38), pp.14306-14318. ⟨10.1039/d2tc02910c⟩. ⟨hal-03797390⟩