Asymmetric Lumino-Transformer: Circularly Polarized Luminescence of Chiral Eu(III) Coordination Polymer with Phase-Transition Behavior

Abstract

A chiral Eu­(III) coordination polymer with phase-transition behavior, [Eu­(+tfc)3(m-dpeb)] n , (+tfc: (+)-3-trifluoroacetylcamphorato, m-dpeb: 1,3-bis­(diphenylphosphorylethynyl)­benzene) was reported for understanding the effect of polymer chain arrangement (orientation effect) on the circularly polarized luminescence (CPL) in a solid system. The phase-transition behavior of the transformable Eu­(III) coordination polymer was characterized using differential scanning calorimetry and powder X-ray diffraction. The Eu­(III) coordination polymer exhibited phase transition at approximately 180 °C. The magnitude of the CPL intensity was drastically changed because of the phase transition, without coordination geometrical change around the Eu­(III) ion. In this study, the orientation effect of a chiral Eu­(III) coordination polymer on the CPL properties in crystalline solid is demonstrated.

Enhanced circularly polarized luminescence of chiral Eu(iii) coordination polymers with structural strain

“…Previously, we reported on the photophysical relationship between the LMCT states and the |g CPL | value. 17 In this study, we successfully observed that the electronic structure of the ligands in a chiral Eu(III) coordination polymer is directly linked to the characteristics of the LMCT excited states and the |g CPL | value. The precise tuning of the structural distortion of the chiral ligands can enhance the |g CPL | value for optical applications.…”

“…Recently, we described the relationship between the LMCT states in chiral Eu(III) compounds and their circularly polarized luminescence (CPL) properties. 16,17 In our previous study, the substituents of chiral phosphine oxide ligands in Eu(III) complexes provided the structural strain in β-diketonate ligands, which affected their coordination geometries, LMCT, and CPL properties. We discussed the strain factor based on the crystal and ligand field (steric structure) for enhancement of the LMCT and CPL bands.…”

“…1c). 17,18 Three chiral Eu(III) coordination polymers, [Eu(+tfc) 3 ( p-dpeb)] n , [Eu(+pfc) 3 ( pdpeb)] n , and [Eu(+hfc) 3 ( p-dpeb)] n (Fig. 1d), were synthesized using these ligands to tune the steric hindrance of the chiral ligands in the Eu(III) coordination polymers.…”

Size-Control Synthesis and Luminescence Properties of Eu(III) Coordination Particles

“…These spectral shapes of luminescence suggest that the coordination geometrical structures around Eu­(III) ions of the Eu­(III) coordination particles are the same as that of the Eu-bulk. A phenomenon was reported that some different crystal structures showed the same coordination geometry near the Eu­(III) ions and the same stark splitting shape in emission spectra …”

Conglomerate, Racemate, and Achiral Crystals of Polymetallic Europium(III) Compounds of Bis- or Tris-β-diketonate Ligands and Circularly Polarized Luminescence Study

“…The chiral conglomerate has a Flack parameter in the range of 0.220(4) to 0.480(4), confirming highly enantiopure crystal structures. A (Δ,Δ,Δ,Δ,Δ,Δ)-[Eu III 6 (TTP) 8 ] monomer unit exhibits a distorted capped square antiprism (CSAP) geometry in their coordination sphere where nine vertices are saturated with eight β-diketonate oxygen atoms and an oxygen atom of a coordinating water molecule (Figure a,b) with an average Eu–Eu distance of 10.092 Å, which seems short enough for an Eu–Eu exciton interaction. , The Eu–O­(β-diketonate oxygen) and Eu–O­(OH 2 ) distances are in the range of 2.378(7)–2.493(7) Å and 2.450(6)–2.548(7) Å, respectively. The total charges of all Eu III and shared Na + ions in a [Eu III 6 (TTP) 8 ] unit are −6 and 5, respectively.…”