Determine the effective symmetry of 10-Eu

Determine the degree of geometric distortion and the resulting effective point-group symmetry of the europium site in the 10-Eu complex, whose crystallographic symmetry is distorted C₂ᵥ, in order to establish whether its effective symmetry is Cₙ, Cₙᵥ, or Cₛ.

Background

The paper examines twelve Eu³⁺-based molecular complexes and relates the branching ratio and oscillator strength of the nominally forbidden ⁵D₀ → ⁷F₀ transition to the local symmetry and ligand-field environment around the Eu³⁺ ion. For 10-Eu, single-crystal X-ray diffraction identifies a distorted C₂ᵥ structure in both polymorphs, but the extent of distortion determines the effective symmetry relevant to the optical transition. The paper explicitly states that this effective symmetry remains uncertain, leaving the classification of the Eu³⁺ site unresolved.

References

For 10-Eu, the symmetry observed through single-crystal X-ray diffraction is distorted C₂ᵥ for both polymorphs; however, the degree of distortion, and therefore the resulting effective symmetries (either Cₙ, Cₙᵥ, or Cₛ) are uncertain.

— Judd-Ofelt analysis and coherent spectroscopy of europium-based molecular complexes for quantum information applications  (2610.13664 - Jobbitt et al., 9 Oct 2026) in Footnote to Table 1