Puzan Agnieszka, Zychowicz Mikolaj, Wang Junhao, Zakrzewski Jakub J, Reczyński Mateusz, Ohkoshi Shin-Ichi, Chorazy Szymon
Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-386 Kraków, Poland.
Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Dalton Trans. 2021 Nov 16;50(44):16242-16253. doi: 10.1039/d1dt03071j.
The interest in the generation of photoluminescence in lanthanide(III) single-molecule magnets (SMMs) is driven by valuable magneto-optical correlations as well as perspectives toward magnetic switching of emission and opto-magnetic devices linking SMMs with optical thermometry. In the pursuit of enhanced magnetic anisotropy and optical features, the key role is played by suitable ligands attached to the 4f metal ion. In this context, cyanido complexes of d-block metal ions, serving as expanded metalloligands, are promising. We report two novel discrete coordination systems serving as emissive SMMs, {[Dy(HO)(tmpo)][PtBr(CN)]}·2HO (1) and {[Dy(HO)(tmpo)][PtBr(CN)]}·2CHCN (2) (tmpo = trimethylphosphine oxide), obtained by combining Dy complexes with uncommon dibromotetracyanidoplatinate(IV) ions, [PtBr(CN)]. They are built of analogous Z-shaped cyanido-bridged {DyPt} molecules but differ in the coordination number of Dy (C.N. = 8 in 1, C.N. = 7 in 2) and the number of coordinated tmpo ligands (three in 1, four in 2) which is related to the applied solvents. As a result, both compounds reveal Dy-centred slow magnetic relaxation but only 1 shows SMM character at zero dc field, while 2 is a field-induced SMM. The relaxation dynamics in both systems is governed by the Raman relaxation mechanism. These effects were analysed using ac magnetic data and the results of the calculations with the support of magneto-optical correlations based on low-temperature high-resolution emission spectra. Our findings indicate that heteroligand halogeno-cyanido Pt complexes are promising precursors for emissive SMMs with the further potential of sensitivity to external stimuli that may be related to the lability of the axially positioned halogeno ligands.
镧系元素（III）单分子磁体（SMMs）中光致发光的产生引起了人们的兴趣，这是由有价值的磁光相关性以及发射磁开关和将SMMs与光学测温联系起来的光磁器件的前景所驱动的。在追求增强磁各向异性和光学特性的过程中，与4f金属离子相连的合适配体起着关键作用。在这种情况下，作为扩展金属配体的d- 块金属离子的氰基配合物很有前景。我们报道了两个用作发光SMMs的新型离散配位体系，{[Dy(HO)(tmpo)][PtBr(CN)]}·2HO (1) 和 {[Dy(HO)(tmpo)][PtBr(CN)]}·2CHCN (2) （tmpo = 三甲基氧化膦），它们是通过将Dy配合物与不常见的二溴四氰基铂（IV）离子[PtBr(CN)]结合而得到的。它们由类似的Z形氰基桥联的{DyPt}分子构成，但Dy的配位数不同（1中C.N. = 8，2中C.N. = 7），且配位的tmpo配体数量不同（1中为三个，2中为四个），这与所使用的溶剂有关。结果，两种化合物都显示出以Dy为中心的慢磁弛豫，但只有1在零直流场下表现出SMM特性，而2是场诱导SMM。两个体系中的弛豫动力学均由拉曼弛豫机制控制。利用交流磁数据以及基于低温高分辨率发射光谱的磁光相关性计算结果对这些效应进行了分析。我们的研究结果表明，异配体卤代氰基铂配合物是发光SMMs的有前景的前体，具有对外部刺激敏感的进一步潜力，这可能与轴向定位的卤代配体的不稳定性有关。
