Asymmetric {Dy4} metallogrid and double-layered {Dy8} cage clusters from carboxylic decorated o-vanillin Schiff bases: syntheses, topological variation, and single molecule magnet behaviors

作者：Wang, Yi-Han; Qin, Yu; Tang, Shen; Teng, Qing-Hu^*; Zhu, Meng-Meng; Peng, Song; Wang, Kai^*; Liang, Fu-Pei^*

来源：New Journal of Chemistry, 2023, 47(4): 2052-2059.

DOI：10.1039/d2nj04701b

• RELAXATION
• DYNAMICS
• HYSTERESIS

There is still great potential to be tapped for polynuclear lanthanide single-molecule magnets (Ln-SMMs) for performance. Toward this goal, the exploration of polynuclear lanthanide clusters (PLnCs) with novel special topologies is critical. Herein, two novel PLnCs, [Dy-4(ov6ca)(6)(CH3OH) (H2O)(2)]center dot 6CH(3)OH center dot;CH3CN center dot H2O (1) and [Dy-8(ov5ca)(6)(a5ca)(4)(ov)(2)(mu-OH)(6)]center dot 6CH(3)OH (2), have been synthesized, where ov6ca(2-), ov5ca(2-), a5ca(-), ov(-) represent the ions of 2-[(o-vanillidene)amino]-6-chlorobenzoic acid, 2-[(o-vanillidene)amino]-5-chlorobenzoic acid, 2-amino-5-chlorobenzoic acid and o-vanillin, respectively. Carboxylic decorated o-vanillin Schiff base ligands H(2)ov6ca and H(2)ov5ca, were constructed as 1 and 2, respectively, and only differ in the position of a Cl-substituent. However, this tiny difference has induced great variation in the nuclearity and topology between 1 and 2. Cluster 1 features a {Dy-4} metallogrid core, where four Dy-III ions are bridged by two O-phenol and two carboxylate groups from ov6ca(2-) ligands but show different coordination geometries. To our knowledge, it is the first {Ln(4)} cluster with such an asymmetric metallogrid topology. While 2 displays a rare double-layered cage cluster topology, in which a pair of butterfly-shaped {Dy-4} units were linked together by four carboxylate groups from ov5ca(2-) ligands. Magnetic measurements revealed that both 1 and 2 exhibit slow magnetic relaxation behavior, with efficient energy barrier (U-eff) values of 93.06 and 66.92 K, respectively.

• 单位
  桂林理工大学