Chirogenesis and Pfeiffer effect in optically inactive Euˡˡˡ and Tbˡˡˡ Tris(β-diketonate) upon intermolecular chirality transfer from Poly- and Monosaccharide Alkyl Esters and α-Pinene: emerging Circularly Polarized Luminescence (CPL) and Circular Dichroism (CD)
Journal
Frontiers in Chemistry
ISSN
2296-2646
Date Issued
2020
Author(s)
Michiya Fujiki
Nara Institute of Science and Technology, Japan
Laibing Wang
Nara Institute of Science and Technology, Japan
Nanami Ogata
Nara Institute of Science and Technology, Japan
Fumio Asanoma
Nara Institute of Science and Technology, Japan
Asuka Okubo
Nara Institute of Science and Technology, Japan
Shun Okazaki
Nara Institute of Science and Technology, Japan
Hiroki Kamite
Nara Institute of Science and Technology, Japan
Jalilah Abd Jalil
Universiti Malaysia Perlis
DOI
10.3389/fchem.2020.00685
Handle (URI)
Abstract
We report emerging circularly polarized luminescence (CPL) at 4f-4f transitions when lanthanide (Euˡˡˡ and Tbˡˡˡ) tris(β-diketonate) embedded to cellulose triacetate (CTA), cellulose acetate butyrate (CABu), D-/L-glucose pentamethyl esters (D-/L-Glu), and D-/L-arabinose tetramethyl esters (D-/L-Ara) are in film states. Herein, 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate (fod) and 2,2,6,6-tetramethyl-3,5-heptanedione (dpm) were chosen as the β-diketonates. The glum value of Eu(fod)3 in CABu are +0.0671 at 593 nm (5 (Formula presented.) F1) and −0.0059 at 613 nm (5 (Formula presented.) F2), respectively, while those in CTA are +0.0463 and −0.0040 at these transitions, respectively. The glum value of Tb(fod)3 in CABu are −0.0029 at 490 nm (5 (Formula presented.) F6), +0.0078 at 540 nm (5 (Formula presented.) F5), and −0.0018 at 552 nm (5 (Formula presented.) F5), respectively, while those in CTA are −0.0053, +0.0037, and −0.0059 at these transitions, respectively. D-/L-Glu and D-/L-Ara induced weaker glum values at 4f-4f transitions of Eu(fod)3, Tb(fod)3, and Tb(dpm)3. For comparison, Tb(dpm)3 in α-pinene showed clear CPL characteristics, though Eu(dpm)3 did not. A surplus charge neutralization hypothesis was applied to the origin of attractive intermolecular interactions between the ligands and saccharides. This idea was supported from the concomitant opposite tendency in upfield 19F-NMR and downfield 1H-NMR chemical shifts of Eu(fod)3 and the opposite Mulliken charges between F-C bonds (fod) and H-C bonds (CTA and D-/L-Glu). An analysis of CPL excitation (CPLE) and CPL spectra suggests that (+)- and (–)-sign CPL signals of Euˡˡˡ and Tbˡˡˡ at different 4f-4f transitions in the visible region are the same with the (+)-and (–)-sign exhibited by CPLE bands at high energy levels of Euˡˡˡ and Tbˡˡˡ in the near-UV region.
Subjects
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