Theoretical Evidence of the Singlet Predominance in the Intramolecular Energy Transfer in Ruhemann's Purple Tb(III) Complexes

Abstract

This work presents a theoretical study on the geometries and intramolecular energy transfer (IET) process of Tb3+‐complexes based on the Ruhemman's purple (RP) as ligands. Density functional theory and its time‐dependent extension are performed to examine the coordination energies and excited states using the ωB97X‐D3/MWB54/def2‐TZVP/polarizable continuum model level of theory. The inclusion of solvent effect causes a blueshift in all excitation energies, which is crucial for a better description of the electronic situations of RP isomers and coordination compounds. The IET rates are assessed for 18 Tb‐RP different compounds, each one with 44 IET pathways, also, it is obtained that the main energy transfer channel comes from the singlet state, in complete agreement with previous experimental data. The energy transfer from the singlet state is mainly composed of the nonradiative absorptions 7F6→5G6 and 7F5→5G5, representing together 97% of the total IET rate. As far as it is known, this is the first time that the solvent effect is included in the IET rates calculation, registering a step toward the development of IET analysis without any experimental or phenomenological input data.

Rationalizing the Thermal Response of Dual‐Center Molecular Thermometers: The Example of an Eu/Tb Coordination Complex

“…The resonance (or energy mismatch) conditions δ = E L −E Ln (the donor-acceptor energy difference) were included by Malta [81] in an analytical expression (Equation S12, Supporting Information) for the spectral overlap integral, well-examined by Smentek and Kędziorski. [90] The shape of the spectral overlap as a function of the bandwidth at half-height of the ligand's state (γ L ) and the δ conditions can also be found in Moura Jr. et al [91] The values of the intensity parameters Ω λ (λ = 2, 4, 6) as well the Ln-O and Ln-N overlap integrals ρ [92] for evaluating the shielding factors (1 − σ K ) were calculated using the JOYSpectra program. [93] The backward energy transfer rates (W b ), the energy returned from acceptor (Ln 3+ ) to donor state (S 1 or T 1 ), were obtained by the Boltzmann's factor exp(−|δ|/k B T).…”

Customized Luminescent Multiplexed Quick‐Response Codes as Reliable Temperature Mobile Optical Sensors for eHealth and Internet of Things

“…[101] The IET rates were calculated according to the approach described in the literature. [43,[102][103][104] The kinetics of an IET process included an equilibrium involving the absorption, IET (both forward and backward energy transfer), radiative and nonradiative decay rates involving the donor moieties (NH/Si of the hybrid; S 1 /T 1 of the main ligands SAand tta -), and Ln 3þ -ion states. This kinetics was described by an appropriate system of rate equations for a hybrid ligand-Ln 3þ unit; the ensemble of these factors enabled the description of macroscopic photophysical properties such as Ln 3þ emission.…”

Employing three-blade propeller lanthanide complexes as molecular luminescent thermometers: study of temperature sensing through a concerted experimental/theory approach

“…Pathways S 1 → [ 7 F 6 → 5 G 6 ] and S 1 → [ 7 F 5 → 5 G 5 ] (Table S7, ESI†) are the dominant ones due to their good energy resonance conditions and high values of reduced matrix elements of the spin operator and (in units of ħ ). 88 Despite the fact that the Tb 3+ 7 F 5 level is not thermally coupled with the 7 F 6 , as in the case of the Eu 3+ for 7 F 1 and 7 F 0 ones, the 7 F 5 level is considered in our calculations due to its long decay time. 89,90 Previous studies pointed out the importance of this level in the IET process.…”

“…). 88 Despite the fact that the Tb 3+ 7 F 5 level is not thermally coupled with the 7 F 6 , as in the case of the Eu 3+ for 7 F 1 and 7 F 0 ones, the 7 F 5 level is considered in our calculations due to its long decay time. 89,90 Previous studies pointed out the importance of this level in the IET process.…”

“…89,90 Previous studies pointed out the importance of this level in the IET process. 88,[91][92][93] In particular, Kasprzycka et al carried out a study on the complex Na[Tb(L) 4 ] (H-L = dimethyl(4-methylphenylsulfonyl)amidophosphate) and the authors showed that if the 7 F 5 is not considered in the IET process as an initial acceptor level, the calculated Q L Tb drops from 0.57 to 0.015, while the measured Q L Tb one is 0.58. 92 Thus, whereas the terbium complex exhibits a dominant S 1 -Tb 3+ IET, the situation with europium complex is reversed and involved mostly a T 1 -Eu 3+ pathway.…”