TY - JOUR
T1 - Energy Transfer Mechanism and Quantitative Modeling of Rate from an Antenna to a Lanthanide Ion
AU - Tanner, Peter A.
AU - Thor, Waygen
AU - Zhang, Yonghong
AU - Wong, Ka Leung
N1 - Funding Information:
K.-L.W. acknowledges funding from the Hong Kong Research Grants Council Research Grant No. 1230020. The authors thank the Max-Planck-Institut für Chemische Energiekonversion for making available the Orca Program. This research was conducted using the resources of the High Performance Cluster Computing Center, Hong Kong Baptist University, which receives funding from the Research Grant Council, University Grant Committee of the HKSAR and Hong Kong Baptist University. The authors also thank Sci-Hub for removing barriers in the way to science. They also thank Dr. Jose Diogo de Lisboa Dutra for private discussions concerning LUMPAC and Prof. O.L. Malta and his group for correspondence. Professor Y. Y. Yeung is thanked for providing the free ion compositions of multiplet terms of some europium complexes.
Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.
PY - 2022/10/20
Y1 - 2022/10/20
N2 - The excitation energy transfer (ET) pathway and mechanism from an organic antenna to a lanthanide ion has been the subject of discussion for many decades. In the case of europium (Eu3+), it has been suggested that the transfer originates from the ligand singlet state or a triplet state. Taking the lanthanide complex Eu(TTA)3(H2O)2 as an example, we have investigated the spectra and luminescence kinetics, mainly at room temperature and 77 K, to acquire the necessary experimental data. We put forward an experimental and theoretical approach to measure the energy transfer rates from the antenna to different Eu3+ levels using the Dexter formulation. We find that transfer from the ligand singlet state to Eu3+ may account for the ET pathway, by combined electric dipole-electric dipole (ED-ED) and ED-electric quadrupole (EQ) mechanisms. The contributions from the triplet state by these mechanisms are very small. An independent systems rate equation approach can effectively model the experimental kinetics results. The model utilizes the cooperative processes that take place on the metal ion and ligand and considers S0, S1, and T1 ligand states in addition to 7F0,1, 5D0, 5D1, and 5DJ (=5L6, 5D3, 5D2 combined) Eu3+ states. The triplet exchange ET rate is estimated to be of the order 107 s-1. The observation of a nanosecond risetime for the Eu3+ 5D1 level does not enable the assignment of the ET route or the mechanism. Furthermore, the 5D1 risetime may be contributed by several processes. Observation of its temperature dependence and also that of the ground-state population can supply useful information concerning the mechanism because the change in metal-ion internal conversion rate has a greater effect than changes in singlet or triplet nonradiative rates. A critical comparison is included for the model of Malta employed in the online software LUMPAC and JOYSpectra. The theoretical treatment of the exchange mechanism and its contribution are now being considered.
AB - The excitation energy transfer (ET) pathway and mechanism from an organic antenna to a lanthanide ion has been the subject of discussion for many decades. In the case of europium (Eu3+), it has been suggested that the transfer originates from the ligand singlet state or a triplet state. Taking the lanthanide complex Eu(TTA)3(H2O)2 as an example, we have investigated the spectra and luminescence kinetics, mainly at room temperature and 77 K, to acquire the necessary experimental data. We put forward an experimental and theoretical approach to measure the energy transfer rates from the antenna to different Eu3+ levels using the Dexter formulation. We find that transfer from the ligand singlet state to Eu3+ may account for the ET pathway, by combined electric dipole-electric dipole (ED-ED) and ED-electric quadrupole (EQ) mechanisms. The contributions from the triplet state by these mechanisms are very small. An independent systems rate equation approach can effectively model the experimental kinetics results. The model utilizes the cooperative processes that take place on the metal ion and ligand and considers S0, S1, and T1 ligand states in addition to 7F0,1, 5D0, 5D1, and 5DJ (=5L6, 5D3, 5D2 combined) Eu3+ states. The triplet exchange ET rate is estimated to be of the order 107 s-1. The observation of a nanosecond risetime for the Eu3+ 5D1 level does not enable the assignment of the ET route or the mechanism. Furthermore, the 5D1 risetime may be contributed by several processes. Observation of its temperature dependence and also that of the ground-state population can supply useful information concerning the mechanism because the change in metal-ion internal conversion rate has a greater effect than changes in singlet or triplet nonradiative rates. A critical comparison is included for the model of Malta employed in the online software LUMPAC and JOYSpectra. The theoretical treatment of the exchange mechanism and its contribution are now being considered.
UR - http://www.scopus.com/inward/record.url?scp=85139566610&partnerID=8YFLogxK
U2 - 10.1021/acs.jpca.2c03965
DO - 10.1021/acs.jpca.2c03965
M3 - Journal article
AN - SCOPUS:85139566610
SN - 1089-5639
VL - 126
SP - 7418
EP - 7431
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 41
ER -