Electronic strain effect on Eu(iii) complexes for enhanced circularly polarized luminescence. Issue 16 (7th April 2020)

• Record Type: Journal Article
• Authors: Tsurui, Makoto; Kitagawa, Yuichi; Fushimi, Koji; Gon, Masayuki; Tanaka, Kazuo; Hasegawa, Yasuchika
• Is Part Of: Dalton transactions. Volume 49:Issue 16(2020)
• Page Start: 5352
• Page End: 5361
• Publication Date: 2020-04-07
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d0dt00699h
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : The structural and electronic strain of ligands promotes the enhancement of the magnitude of circularly polarized luminescence in chiral Eu(iii ) complexes. Abstract : Luminescent Eu(iii ) complexes with point-chiral phosphine oxide ligands, [Eu(hfa)3 (( R, R )-B2QPO)] (hfa: hexafluoroacetylacetonato, B2QPO: 2, 3-bis( tert -butylmethylphosphine oxide)quinoxaline) and [Eu(hfa)3 (( R )-B3QPO)] (B3QPO: 2- tert -butylmethylphosphine oxide-3-(di- tert -butylphosphineoxide)quinoxaline), are reported for the investigation of the electronic strain effect on the coordination sphere. Single crystal X-ray crystallography reveals the strong structural strain of the hfa ligands in [Eu(hfa)3 (( R, R )-B2QPO)]. The emission quantum yields of [Eu(hfa)3 (( R, R )-B2QPO)] in solution (55%) and solid (63%) are comparable to those of previously reported bright luminescent Eu(iii ) complexes. The chiroptical properties of [Eu(hfa)3 (( R, R )-B2QPO)] and [Eu(hfa)3 (( R )-B3QPO)] were characterized using circular dichroism (CD) and circularly polarized luminescence (CPL) spectra. The dissymmetry factor of [Eu(hfa)3 (( R, R )-B2QPO)] was estimated to be 0.08. The chiroptical phenomena of the Eu(iii ) complexes are closely related to their structural (geometry) and electronic (LMCT: ligand-to-metal charge transfer) strains.