Wydział Chemii

Ewa Kasprzycka

Albano N. Carneiro Neto

Viktor A. Trush

Oscar L. Malta

Lucjan Jerzykiewicz

Vladimir M. Amirkhanov

Janina Legendziewicz

Paula Gawryszewska

2022

Spectrochimica Acta Part A-Molecular and Biomolecular Spectroscopy

274

121072/1-121072/11

10.1016/j.saa.2022.121072

Naukowa

Angielski

Artykuł

We present the experimental and theoretical results that made it possible to propose the energy transfer mechanism for a Yb complex with a large energy gap between the ligand and Yb excited states using a theoretical model and experimental data. Absorption and emission spectroscopy in the 300–4 K range is used for the study of the Yb³⁺ compound with N-phosphorylated sulfonamide (Na[YbL₄]), which, despite the large energy gap, is characterized by high emission sensitization efficiency (η_sens = 40%) and relatively long Yb³⁺ emission lifetime (27 μs). The crystal structure of Na[YbL₄], radiative lifetime (930 μs), refractive index (1.46), intrinsic (3.0%), and overall (1.3%) emission quantum yield were determined. To obtain the electronic properties of the Na[YbL₄], a time-dependent density functional theory (TD-DFT) was performed. The intramolecular energy transfer (IET) rates from the excited states S₁ and T₁ to the Yb³⁺ ion as well as between the ligand and the ligand-to-metal charge transfer (LMCT) states were calculated. Once the intersystem crossing S₁ → T₁ is not so effective due to a large energy gap between S₁ and T₁ (≈10000 cm⁻¹), it has been shown that the LMCT state acts as an additional channel to feed the T₁ state. Then, the T₁ can transfer energy to the Yb^{3+ 2}F_5/2 energy level (), where is dominated by the exchange mechanism. Based on IET and a rate equation model, the overall emission quantum yield Q^L_Ln was simulated with and without the LMCT, this also confirmed that the pathway S₁ → LMCT → T₁ → Yb³⁺ is more likely than the S₁ → T₁ → Yb³⁺ one.

Ytterbium, Absorption spectroscopy, Luminescence, N-phosphorylated sulfonamide, Energy transfer, Theoretical calculations

http://dx.doi.org/10.1016/j.saa.2022.121072

http://www.elsevier.com