Babaei Zarch Malihe, Mirzaei Masoud, Bazargan Maryam, Gupta Sandeep K, Meyer Franc, Mague Joel T
Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad 9177948974, Iran.
Institut für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany.
Dalton Trans. 2021 Nov 2;50(42):15047-15056. doi: 10.1039/d1dt01708j.
As an extension of our interest in polyoxometalates (POMs) and lanthanoids, we report the design and synthesis of two polyoxometalate-based frameworks under hydrothermal conditions; [Ho(PDA)(HO)][(SiO)@WO]·8HO (1) and [Tb(PDA)(HO)][(SiO)@WO]·4HO (2) (HPDA = 1,10-phenanthroline-2,9-dicarboxylic acid). Both hybrids have been characterized by elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, and powder/single-crystal X-ray diffraction. According to the structural analysis, 1 and 2 consist of 2D-cationic coordination polymers based on the respective lanthanoids and PDA as well as Keggin anions that reside in the interspaces between two adjacent layers as discrete counterions connected by extensive hydrogen bonding. Although the overall structures of 1 and 2 are composed of cationic and anionic layers, there are many differences in the cationic layers such as various coordination modes of PDA, different void shapes, and the existence of dinuclear Tb(III) units only in 2. Frameworks 1 and 2 were further characterized by dc and ac magnetic measurements and both exhibit slow relaxation of magnetization at low temperatures under an applied dc field. Their single-molecule magnet (SMM) properties are investigated, where weak field-induced SMM behaviour is observed at low temperatures in dynamic magnetic studies.
作为我们对多金属氧酸盐（POMs）和镧系元素研究兴趣的延伸，我们报道了在水热条件下两种基于多金属氧酸盐的框架的设计与合成；[Ho(PDA)(H₂O)][(SiO₄)@WO₄]·8H₂O (1) 和 [Tb(PDA)(H₂O)][(SiO₄)@WO₄]·4H₂O (2) （HPDA = 1,10 - 菲咯啉 - 2,9 - 二羧酸）。两种杂化物均通过元素分析、傅里叶变换红外光谱、热重分析以及粉末/单晶X射线衍射进行了表征。根据结构分析，1和2由基于各自镧系元素和PDA的二维阳离子配位聚合物以及作为离散抗衡离子存在于两个相邻层之间间隙中的Keggin阴离子组成，这些阴离子通过广泛的氢键相连。尽管1和2的整体结构均由阳离子层和阴离子层组成，但阳离子层存在许多差异，例如PDA的各种配位模式、不同的空隙形状以及仅在2中存在双核Tb(III)单元。框架1和2通过直流和交流磁性测量进一步表征，并且在施加直流磁场的低温下均表现出磁化强度的缓慢弛豫。研究了它们的单分子磁体（SMM）性质，在动态磁性研究中，在低温下观察到了弱场诱导的SMM行为。
