Photoresponsive Magnetic Relaxation Behavior of a Highly Stable π···π Interaction-Stacked Framework Based on a Dy<sup>III</sup> Single-Ion Magnet
Xue-Jing Luo, Ying Liu, Huai-Dong Pan, Song Peng, Zhao‐Bo Hu, Qing‐Hu Teng, Yan Li, Fu‐Pei Liang, Kai Wang
Abstract
Endowing lanthanide single-ion magnets (Ln-SIMs) with high stability and stimulus responsiveness is of significance for the practical applications of these novel magnetic materials, but still of challenge at present. Herein, we report on a highly stable and photoresponsive Ln-SIM system achieved by designing and synthesizing a π···π interaction-stacked framework based on Dy III -SIM ( πOF-1 ). Its molecular formula is [Dy(thqa)] (H 3 thqa = tris[(8-hydroxyquinoline-2-yl)methylene]amino). Each of its C 3 -symmetric molecules consists of a thqa 3– ligand and a Dy III ion, and it is linked to three neighbors by intermolecular π···π interactions, forming a supermolecular two-dimensional (2D) honeycombed topology. Such unique structure endows πOF - 1 with not only air and thermal stability but also excellent chemical stability in different solvents, even in alkali solutions, including a 20 M NaOH aqueous solution. Dual magnetic relaxation behavior was observed in πOF - 1 . Magnetic dilution revealed that it is related to π···π-mediated intermolecular magnetic interactions. More significantly, both the static magnetic susceptibility and the dual-relaxation behavior of πOF - 1 show response to photoirradiation, which could be ascribed to the photo-triggered intermolecular π → π* charge transfer (CT). So far as we know, πOF - 1 could be the first Ln-SIM system possessing both a high stability and photoresponsiveness, and also the first photoresponsive Ln-SIM supermolecular system that does not rely on the single-crystal to single-crystal (SCSC) structural transformation. Its successful design and synthesis suggests that the introduction of π···π interactions can be a new strategy to fabricate stable and/or photoresponsive Ln-SIMs.