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Synthesis and Chiroptical Properties of Chiral Carbazole‐Based BODIPYs
Author(s) -
Maeda Chihiro,
Suka Keita,
Nagahata Keiji,
Takaishi Kazuto,
Ema Tadashi
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201904954
Subject(s) - carbazole , diastereomer , bodipy , chemistry , luminescence , fluorescence , photochemistry , triethylamine , fluorescence spectroscopy , crystallography , stereochemistry , materials science , organic chemistry , physics , optoelectronics , quantum mechanics
Abstract A series of carbazole‐based boron dipyrromethenes (BODIPYs) 2 a – g bearing binaphthyl units have been synthesized by the Et 2 AlCl‐mediated reaction of the corresponding BODIPY difluorides 1 a – g with 1,1′‐binaphthalene‐2,2′‐diol. Substituents such as halogen, nitrile, and amino groups were tolerated under the reaction conditions, and the reaction of the phenylethynyl‐substituted 1 h gave ( R , R )‐ 3 h bearing two binaphthyl units. The chiroptical properties of these dyes with different substituents were investigated by UV/Vis, CD, fluorescence, and circularly polarized luminescence (CPL) spectroscopy. The CD spectra showed Cotton effects in the absorption region of the BODIPY moieties. In addition, they showed CPL both in solution and in the solid state. Interestingly, several dyes recorded higher g lum values in the solid state, probably due to intermolecular interactions. Because ( R , R )‐ 3 h recorded relatively low g lum values, the diastereomer ( R , S )‐ 3 h was prepared. The ( R , S ) diastereomer showed intense CPL, which suggests a synergetic effect of the two binaphthyl groups. Finally, chiral carbazole‐based BODIPY dimers have been synthesized for the first time and their chiroptical properties were investigated. They showed redshifted fluorescence and CPL, which reached the near‐IR (NIR) region in the solid state.