The Rational Design and Preparation of Cyanometalate-Based Single-Molecule Magnets

本课题的目的是将新型单分子磁性材料（SMMs）的合成及其详细表征与基于分子建模方法和量子化学方法的相应分子和晶体结构的准确预测相结合，从而在优化结构的基础上可靠地计算SMMs的关键电子参数。这种新颖的组合方法用于合理设计smm，然后是它们的制备和表征，与该领域通常基于偶然性的发展形成鲜明对比，它依赖于我们将高级理论与经验建模和实验工作相结合的悠久传统。希望这将使我们能够为高密度磁信息存储等应用生产新的定制材料。该项目延续了我们早期的工作，详细分析了一系列六氰金属酸盐基寡核配合物的电子性质，结合了配体场和DFT方法，并涉及矢量耦合方法来彻底研究更大的系统。实验工作以Cr3+， Fe3+， Mn3+和Co3+的六氰金属酸盐为基础，用单核[NiII(L)]2+和[CuII(L)]2+配合物（L是五齿或四齿的比斯匹啶配体）作为末端片段，形成线性和弯曲的氰桥式三核配合物。初步的理论研究得出了一套合成新型纳米材料的规则，并在很大程度上得到了实验数据的证实。然而，很明显，复杂几何形状的微小扭曲通常会导致磁各向异性的降低和阻塞温度的降低。因此，有必要准确预测结构特性，除了实验工作外，这也是本拨款提案的重点之一。

The aim of the proposal is to combine the synthesis of novel single-molecule magnetic materials (SMMs) and their detailed characterization with the accurate prediction of the corresponding molecular and crystal structures, based on molecular modeling approaches, and with quantum-chemical methods, which will allow to reliably computing the crucial electronic parameters of SMMs on the basis of the optimized structures. This novel combined approach for a rational design of SMMs, followed by their preparation and characterization, is in sharp contrast to the usual serendipity-based developments in this area, and it relies on our long tradition to combine high-level theory with empirical modeling and experimental work. It is hoped that it will allow us to produce novel tailor-made materials for applications such as high density magnetic information storage. This project follows our earlier work on the detailed analysis of the electronic properties of a series of hexacyanometalate-based oligonuclear complexes with a combination of ligand field and DFT methods, and involving a vector coupling approach to thoroughly study larger systems. The experimental work was based on hexacyanometalates of Cr3+, Fe3+, Mn3+ and Co3+, which were used to form linear and bent cyano-bridged trinuclear complexes with the mononuclear [NiII(L)]2+ and [CuII(L)]2+ complexes (L is a penta- or tetradentate bispidine ligand) as terminal fragments. The preliminary theoretical studies have resulted in a set of rules for the synthesis of novel SMMs, and these have largely been confirmed by the experimental data. However, it became clear that subtle distortions of the complex geometries generally lead to a reduction of the magnetic anisotropy and a decrease of the blocking temperature. Therefore, there is a need to accurately predict the structural properties and, apart from the experimental work, this is one of the focal points of the present grant proposal.