AUTHOR=Fujiki Michiya , Wang Laibing , Ogata Nanami , Asanoma Fumio , Okubo Asuka , Okazaki Shun , Kamite Hiroki , Jalilah Abd Jalil 

TITLE=Chirogenesis and Pfeiffer Effect in Optically Inactive EuIII and TbIII 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

VOLUME=8

YEAR=2020

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2020.00685

DOI=10.3389/fchem.2020.00685

ISSN=2296-2646

ABSTRACT=<p>We report emerging circularly polarized luminescence (CPL) at 4<italic>f-</italic>4<italic>f</italic> transitions when lanthanide (Eu<sup>III</sup> and Tb<sup>III</sup>) tris(β-diketonate) embedded to cellulose triacetate (<bold>CTA</bold>), cellulose acetate butyrate (<bold>CABu</bold>), <italic>D</italic>-/<italic>L</italic>-glucose pentamethyl esters (<bold><italic>D</italic>-</bold>/<bold><italic>L</italic>-Glu</bold>), and <italic>D</italic>-/<italic>L</italic>-arabinose tetramethyl esters (<bold><italic>D</italic>-</bold>/<bold><italic>L</italic>-Ara</bold>) 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 <italic>g</italic><sub>lum</sub> value of Eu(fod)<sub>3</sub> in <bold>CABu</bold> are +0.0671 at 593 nm (<sup>5</sup><inline-formula><mml:math id="M1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mtext>D</mml:mtext></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msub><mml:msup><mml:mrow><mml:mo>→</mml:mo></mml:mrow><mml:mrow><mml:mn>7</mml:mn></mml:mrow></mml:msup></mml:math></inline-formula>F<sub>1</sub>) and −0.0059 at 613 nm (<sup>5</sup><inline-formula><mml:math id="M2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mtext>D</mml:mtext></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msub><mml:msup><mml:mrow><mml:mo>→</mml:mo></mml:mrow><mml:mrow><mml:mn>7</mml:mn></mml:mrow></mml:msup></mml:math></inline-formula>F<sub>2</sub>), respectively, while those in <bold>CTA</bold> are +0.0463 and −0.0040 at these transitions, respectively. The <italic>g</italic><sub>lum</sub> value of Tb(fod)<sub>3</sub> in <bold>CABu</bold> are −0.0029 at 490 nm (<sup>5</sup><inline-formula><mml:math id="M3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mtext>D</mml:mtext></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub><mml:msup><mml:mrow><mml:mo>→</mml:mo></mml:mrow><mml:mrow><mml:mn>7</mml:mn></mml:mrow></mml:msup></mml:math></inline-formula>F<sub>6</sub>), +0.0078 at 540 nm (<sup>5</sup><inline-formula><mml:math id="M4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mtext>D</mml:mtext></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub><mml:msup><mml:mrow><mml:mo>→</mml:mo></mml:mrow><mml:mrow><mml:mn>7</mml:mn></mml:mrow></mml:msup></mml:math></inline-formula>F<sub>5</sub>), and −0.0018 at 552 nm (<sup>5</sup><inline-formula><mml:math id="M5" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mtext>D</mml:mtext></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub><mml:msup><mml:mrow><mml:mo>→</mml:mo></mml:mrow><mml:mrow><mml:mn>7</mml:mn></mml:mrow></mml:msup></mml:math></inline-formula>F<sub>5</sub>), respectively, while those in <bold>CTA</bold> are −0.0053, +0.0037, and −0.0059 at these transitions, respectively. <bold><italic>D</italic>-</bold>/<bold><italic>L</italic>-Glu</bold> and <bold><italic>D</italic>-</bold>/<bold><italic>L</italic>-Ara</bold> induced weaker <italic>g</italic><sub>lum</sub> values at 4<italic>f-</italic>4<italic>f</italic> transitions of Eu(fod)<sub>3</sub>, Tb(fod)<sub>3</sub>, and Tb(dpm)<sub>3</sub>. For comparison, Tb(dpm)<sub>3</sub> in α-pinene showed clear CPL characteristics, though Eu(dpm)<sub>3</sub> 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 <sup>19</sup>F-NMR and downfield <sup>1</sup>H-NMR chemical shifts of Eu(fod)<sub>3</sub> and the opposite Mulliken charges between <italic>F</italic>-C bonds (fod) and <italic>H</italic>-C bonds (<bold>CTA</bold> and <bold><italic>D</italic>-</bold>/<bold><italic>L</italic>-Glu</bold>). An analysis of CPL excitation (CPLE) and CPL spectra suggests that (+)- and (–)-sign CPL signals of Eu<sup>III</sup> and Tb<sup>III</sup> at different 4<italic>f-</italic>4<italic>f</italic> transitions in the visible region are the same with the (+)-and (–)-sign exhibited by CPLE bands at high energy levels of Eu<sup>III</sup> and Tb<sup>III</sup> in the near-UV region.</p>