Antenna triplet DFT calculations to drive the design of luminescent Ln³⁺complexes

Abstract

Density Functional Theory-based methods have been exploited to look into the structural, vibrational and electronic properties of antenna ligands, all of them crucial points for a reliable design of customized...

Nature of the Ligand-Centered Triplet State in Gd3+β-Diketonate Complexes as Revealed by Time-Resolved EPR Spectroscopy and DFT Calculations

“…This implies that the central metal and the ligands are mostly independent, and electronic properties are substantially unaffected upon moving from the isolated fragments to the complex. 2 , 28 , 29 Thus, the smaller size of the free ligand compared to that of the corresponding complex allows the estimation of ligand ZFS parameters through more accurate calculations, and the results can be then transferred to their Gd 3+ complexes.…”

“…Experimental crystal structures of P1 and 1 – 3 are consistent with the presence of multiple rotamers differing for the relative orientation of the aromatic rings. 2 Triplet geometries needed for ZFS parameters have therefore been optimized for all four possible rotamers, herein labeled A, B, C, and D (see Figure S5 of the Supporting Information ). B and C rotamers may be obtained by flipping either the thienyl moiety (B) or the PAH fragment (C) of the predominant species A. Rotamer D is generated by flipping both the thienyl group and the PAH fragment.…”

“… 30 The detailed description of the calculations for rotational barriers and their values have been reported in a previous work. 2 Experimental and theoretical | D | and | E | triplet values for all possible rotamers of P0 / P1 and 1 – 3 are reported in Table 2 .…”

“… 1 For instance, lanthanide luminescence-based thermometric features are tightly bound to the triplet state energy, in particular when the back-energy transfer is considered. 2 − 7 Besides its energy, the design of novel luminescent systems with tailored properties requires a detailed knowledge of the triplet spin distribution over the molecular skeleton. Indeed, energy transfer pathways are sometimes directly influenced by the specific spatial distribution of the spin density in the sensitizer ligand and by the triplet energy.…”

Accessing lanthanide-based, in situ illuminated optical turn-on probes by modulation of the antenna triplet state energy

“…In contrast, the commonly used vertical approach, where T1 and the S0 share the same geometry, gives a larger energy gap, since the calculated T1 state exists in a vibrationally excited state. [39][40][41] Solvation effects were included in the calculations using the solvent model based on density (SMD) method and the previously optimized polarizable continuum model (PCM) radius was used for Tb(III) in all solvation calculations without scaling (α = 1.0). 42 Spin density plots of the optimized T1 state for all of the complexes confirmed that the spin density was located on the antenna arm of the ligand (Figure 3A).…”