Solid‐State Near‐Infrared Circularly Polarized Luminescence from Chiral Yb^III‐Single‐Molecule Magnet

Abstract

A field‐induced chiral YbIII Single‐Molecule Magnet (SMM) displayed an unprecedented near‐infrared circularly polarized luminescence (NIR‐CPL) in the solid‐state. The bridging bis(1,10‐phenantro[5,6b])tetrathiafulvalene triad (L) allowed an efficient sensitization of the NIR 2F5/2→2F7/2 emission while the NIR‐CPL is associated to the f‐f transitions of the YbIII ion bearing chiral β‐diketonate derived‐camphorate ancillary ligands.

Chiral or Luminescent Lanthanide Single-Molecule Magnets Involving Bridging Redox Active Triad Ligand

“…The two complexes 1 and 2 displayed two monoelectronic oxidations respectively determined at 0.87 V/1.22 V and 0.83 V/1.17 V (vs. SCE) (Figures S3 and S4, Table S4) and attributed to the formation of the radical cation and dication species of the TTF core. These potential values are in line with those observed for their analogs previously published [58,59]. Cyclic voltammetry demonstrated the reversible redox-activity of the two triad-based complexes.…”

“…The precursor Yb(hfac) 3 (H 2 O) 2 (hfac − = 1,1,1,5,5,5-hexafluoroacetylacetonate) [79], Dy((+)facam) 3 (facam − = 3-trifluoro-acetyl-(+)-camphorato anion) [58] and the bis(1,10phenantro [5,6-b])tetrathiafulvalene ligand [57] were synthesized by following previously reported methods. All other reagents were purchased from Aldrich Co., Ltd. (St. Louis, MO, USA) used without further purification.…”

“…One could remark that changing the ancillary hfac − with the facam − ligand enhanced the magnetic performances for both Dy III and Yb III . Indeed, at 2 K, 1 displayed a χ M " peak centered at 1500 Hz while [Yb(facam) 3 (L)] 2 displayed a χ M " peak centered at 100 Hz [58]. Similarly, 2 displayed a χ M " peak centered at 1000 Hz (H = 0 Oe) and 0.…”

“…Such NIR signal is attributed to the Yb III centered 2 F 5/2 → 2 F 7/2 emission. The TTF-centered dyads or triads have been demonstrated to be efficient chromophores for the sensitization of NIR lanthanide luminescence through the antenna process [18,58]. Such efficiency for 1 is proven by the absence of residual ligand-centered emission which attests to a rather efficient energy transfer from the triad L to the Yb III ion.…”

“…Among the plethora of chemical substituents [50,51], the 1,10phenanthroline (phen) is a remarkable choice to design donor-acceptor dyads (called also push-pull ligands) [52][53][54][55] or acceptor-donor-acceptor triads [56,57]. Once associated with metallic precursors, auspicious optical and magnetic properties are observed highlighted by the recent design of a redox-active chiral luminescent SMM displaying circularly polarized luminescence [58].…”