Ottonelli Massimo, Izzo Gaetano Michele Maurizio, Rizzo Fabio, Musso Gianfranco, Dellepiane Giovanna, Tubino Riccardo
INFM, INSTM e Dipartimento di Chimica e Chimica Industriale, Università di Genova, Via Dodecaneso 31, I-16146 Genova, Italy.
J Phys Chem B. 2005 Oct 20;109(41):19249-56. doi: 10.1021/jp053314n.
We use a simple quantum chemical semiempirical procedure to study the electronic properties of organic-lanthanide complexes, taking as a model system Er(8-hydroxyquinolinate)3. Among the problems inherent to such a study is the fact that the lanthanide ion has never been parametrized in any of the standard semiempirical Hamiltonians. To overcome this difficulty, the lanthanide ion is replaced by a different but somewhat similar parametrized ion, or merely by a point charge. Good agreement with experiment, where available, is obtained, particularly in the former case. In fact, the electronic properties of the complex (apart from the emission properties) are seen to be scarcely affected by the nature of the lanthanide ion itself, but the core interactions between the metal ion and the ligand units play a relevant role, also in the calculation of the excitation energies. In particular, the ordering and separation of both singlet and triplet excited states are affected. The main conclusion is that to describe in detail the mechanism of the energy-transfer process occurring in the complex it is essential to take into account the geometry relaxation effects in the excited states.
我们采用一种简单的量子化学半经验方法来研究有机镧系配合物的电子性质，以Er(8-羟基喹啉)₃作为模型体系。此类研究中固有的问题之一是，在任何标准半经验哈密顿量中，镧系离子都从未被参数化。为克服这一困难，镧系离子被一个不同但有些类似的参数化离子取代，或者仅仅被一个点电荷取代。在有实验数据可对比的情况下，能得到与实验结果的良好吻合，特别是在前一种情况下。事实上，配合物的电子性质（除发射性质外）几乎不受镧系离子本身性质的影响，但金属离子与配体单元之间的核心相互作用在激发能的计算中也起着重要作用。特别是，单重态和三重态激发态的排序和间距都会受到影响。主要结论是，要详细描述配合物中发生的能量转移过程的机制，必须考虑激发态的几何弛豫效应。
