Two pairs of chiral Yb enantiomers presenting distinct NIR luminescence and circularly polarized luminescence performances with giant differences in second-harmonic generation responses

• Published in: Dalton transactions : an international journal of inorganic chemistry 2023-12, Vol.52 (47), p.17758-17766
• Main Authors: Du, Xiaodi, Zhang, Zhiqiang, Gao, Congli, Li, Fengcai, Li, Xi-Li
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d3dt03324d

By introducing enantiomerically pure mono-bidentate N-donor ligands (L R /L S ) into Yb(btfa) 3 (H 2 O) 2 and Yb(dbm) 3 (H 2 O), respectively, two pairs of chiral Yb III enantiomers, namely Yb(btfa) 3 L R /Yb(btfa) 3 L S ( D-1/L-1 ) and [Yb(dbm) 3 L R ]·[Yb(dbm) 3 (C 2 H 5 OH)]/[Yb(dbm) 3 L S ]·[Yb(dbm) 3 (C 2 H 5 OH)] ( D-2/L-2 ) were isolated, where btfa − = 3-benzoyl-1,1,1-trifluoroacetonate, dbm − = dibenzoylmethanate, and L R /L S = (−)/(+)-4,5-pinenepyridyl-2-pyrazine. D-1/L-1 possess mononuclear structures in which the Yb III ions are eight-coordinated, while D-2/L-2 show cocrystal structures containing Yb(dbm) 3 (L R /L S ) and Yb(dbm) 3 (C 2 H 5 OH) moieties in which the two Yb III ions are eight and seven-coordinated, respectively. They not only feature different molecular structures but also present distinct linear and nonlinear optical performances. Chiral mononuclear D-1 has better near infrared photo-luminescence (NIR-PL) and circularly polarized luminescence (CPL) performances than chiral cocrystal D-2 . More remarkably, D-1/L-1 show large second-harmonic generation (SHG) responses (up to 1.25/1.28 × KDP) 18/16 times those of D-2/L-2 (0.07/0.08 × KDP). In addition, D-2/L-2 represent the first examples of lanthanide cocrystal complexes with NIR-PL, NIR-CPL and SHG properties. We demonstrate that chiral mononuclear Yb III enantiomers have better NIR-PL, CPL and SHG performances than chiral cocrystal ones.