Carneiro Neto Albano N, Moura Renaldo T, Carlos Luís D, Malta Oscar L, Sanadar Martina, Melchior Andrea, Kraka Elfi, Ruggieri Silvia, Bettinelli Marco, Piccinelli Fabio
Physics Department and CICECO-Aveiro Institute of Materials, University of Aveiro, 3810-193Aveiro, Portugal.
Department of Chemistry and Physics, Federal University of Paraíba, 58397-000Areia, Brazil.
Inorg Chem. 2022 Oct 17;61(41):16333-16346. doi: 10.1021/acs.inorgchem.2c02330. Epub 2022 Oct 6.
In this work, we investigated from a theoretical point of view the dynamics of the energy transfer process from the ligand to Eu(III) ion for 12 isomeric species originating from six different complexes differing by nature of the ligand and the total charge. The cationic complexes present the general formula [Eu(L)(HO)] (where L = bpcd = ,'-bis(2-pyridylmethyl)--1,2-diaminocyclohexane ,'-diacetate; bQcd = ,'-bis(2-quinolinmethyl)--1,2-diaminocyclohexane ,'-diacetate; and bQcd = ,'-bis(2-isoquinolinmethyl)-1,2-diaminocyclohexane ,'-diacetate), while the neutral complexes present the Eu(L)(HO) formula (where L = PyC3A = -picolyl-,','--1,2-cyclohexylenediaminetriacetate; QC3A = -quinolyl-,','-1,2-cyclohexylenediaminetriacetate; and QC3A = -isoquinolyl-,','-1,2-cyclohexylenediaminetriacetate). Time-dependent density functional theory (TD-DFT) calculations provided the energy of the ligand excited donor states, distances between donor and acceptor orbitals involved in the energy transfer mechanism (), spin-orbit coupling matrix elements, and excited-state reorganization energies. The intramolecular energy transfer (IET) rates for both singlet-triplet intersystem crossing and ligand-to-metal (and vice versa) involving a multitude of ligand and Eu(III) levels and the theoretical overall quantum yields (ϕ) were calculated (the latter for the first time without the introduction of experimental parameters). This was achieved using a blend of DFT, Judd-Ofelt theory, IET theory, and rate equation modeling. Thanks to this study, for each isomeric species, the most efficient IET process feeding the Eu(III) excited state, its related physical mechanism (exchange interaction), and the reasons for a better or worse overall energy transfer efficiency (η) in the different complexes were determined. The spectroscopically measured ϕ values are in good agreement with the ones obtained theoretically in this work.
在本工作中，我们从理论角度研究了12种异构物种从配体到铕（III）离子的能量转移过程动力学，这些异构物种源自六种不同的配合物，它们在配体性质和总电荷方面存在差异。阳离子配合物的通式为[Eu(L)(HO)]（其中L = bpcd = ，'-双(2 - 吡啶甲基)--1,2 - 二氨基环己烷，'-二乙酸酯；bQcd = ，'-双(2 - 喹啉甲基)--1,2 - 二氨基环己烷，'-二乙酸酯；bQcd = ，'-双(2 - 异喹啉甲基)-1,2 - 二氨基环己烷，'-二乙酸酯），而中性配合物的化学式为Eu(L)(HO)（其中L = PyC3A = - 吡啶甲基，','--1,2 - 环己二胺三乙酸酯；QC3A = - 喹啉基，','-1,2 - 环己二胺三乙酸酯；QC3A = - 异喹啉基，','-1,2 - 环己二胺三乙酸酯）。含时密度泛函理论（TD - DFT）计算提供了配体激发供体态的能量、能量转移机制中涉及的供体和受体轨道之间的距离（）、自旋 - 轨道耦合矩阵元以及激发态重组能。计算了单重态 - 三重态系间窜越以及涉及多个配体和铕（III）能级的配体到金属（反之亦然）的分子内能量转移（IET）速率以及理论总量子产率（ϕ）（后者首次在不引入实验参数的情况下计算）。这是通过结合DFT、贾德 - 奥费尔特理论、IET理论和速率方程建模实现的。通过这项研究，确定了每种异构物种中向铕（III）激发态供能的最有效IET过程、其相关的物理机制（交换相互作用）以及不同配合物中总能量转移效率（η）更好或更差的原因。光谱测量的ϕ值与本工作中理论获得的值高度吻合。
