Combined Experimental and Theoretical Studies on Planar Chirality of Partially Overlapped C2-Symmetric [3.3](3,9)Dicarbazolophanes

Keita Tani; Risa Imafuku; Kanae Miyanaga; Miyuki Eiraku Masaki; Haruka Kato; Kazushige Hori; Koji Kubono; Masatsugu Taneda; Takunori Harada; Kenta Goto; Fumito Tani; Tadashi Mori

doi:10.1021/acs.jpca.0c00286

Combined Experimental and Theoretical Studies on Planar Chirality of Partially Overlapped C₂-Symmetric [3.3](3,9)Dicarbazolophanes

J Phys Chem A. 2020 Mar 12;124(10):2057-2063. doi: 10.1021/acs.jpca.0c00286. Epub 2020 Mar 3.

Authors

Affiliations

¹ Division of Natural Science, Osaka Kyoiku University, Asahigaoka, Kashiwara, Osaka 582-8582, Japan.
² Department of Integrated Science and Technology, Faculty of Science and Technology, Oita University, Dannoharu 700, Oita City 870-1192, Japan.
³ Institute for Materials Chemistry and Engineering, Kyushu University, Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
⁴ Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita 565-0871, Japan.

PMID: 32077298
DOI: 10.1021/acs.jpca.0c00286

Abstract

Partially overlapped dicarbazolophanes exhibit a planar chirality. In this study, C₂-symmetrical [3.3](3,9)dicarbazolophane derivatives (CZ1-CZ3) have been optically resolved by preparative chiral high-performance liquid chromatography for the first time. In their circular dichroism (CD) spectra, moderate Cotton effects (CEs) were observed for their ¹L_b and ¹L_a transitions (|Δε| = 10-12 and 51-57 M^-1 cm^-1, respectively), while intense CEs were notified in their ¹B transitions (|Δε| = 156-216 M^-1 cm^-1), absorption dissymmetry (g_abs) factors being in orders of 10^-2. Circularly polarized luminescence spectrum was also obtained for cyanamide derivative CZ1, with a comparative luminescence dissymmetry (g_lum) factor of 0.013. A computational investigation was applied to address the factors for such remarkable chiroptical responses in these dicarbazolophanes of planar chirality. Absolute configurations were unambiguously determined by the comparison of experimental and theoretical CD spectra, which was affirmed by the X-ray crystal structural analysis of enantiomerically pure sulfonamide derivative CZ2.