From dinuclear to two-dimensional Dy(iii) complexes: single crystal-single crystal transformation and single-molecule magnetic behavior

Regulating the magnetic properties through structural transformation and multifunctional magnetic bistable materials attracts increasing interest in the research area of molecular magnets. Herein, we have obtained a two-dimensional Dy3+ metal-organic framework {[Dy-2(H2L)(2)(H2O)(CH3OH)](ClO4)(2)& BULL;H2O}(n) (1) and three dinuclear Dy-2 complexes 2-4 based on the new diacylhydrazone ligand H4L. The structural analyses show that the Dy3+ ions have a coordination geometry of Hula-hoop (C-2v) and are coordinated by one or two trans phenoxy groups of the ligand H3L- or H2L2- with Dy-O-phenoxy bond distances in the range of 2.175-2.252 & ANGS;. The 2D complex (1) exhibits excellent thermal stability, a broad ligand-based fluorescence emission band and selective adsorption capacity for rhodamine B. The dinuclear Dy-2 complexes (2-4) undergo consecutive single-crystal to single-crystal transformation in the mother liquor. Alternating-current (ac) susceptibility measurements reveal that 1-3 display typical single-molecule magnetic properties with effective energy barriers of 91.6 K, 106.3 K and 91.9 K, respectively. Ab initio calculations evidence good magnetic anisotropy with the calculated energy of the first excited state as high as 392.5 K (272.8 cm(-1)) for 1, 257.5 K (179.0 cm(-1)) for 2 and 250.2 K (173.9 cm(-1)) for 3, respectively.

Automated summary

Regulating the magnetic properties through structural transformation and multifunctional magnetic bistable materials attracts increasing interest in the research area of molecular magnets. Herein, we report the synthesis and characterization of a two-dimensional Dy3+ metal-organic framework and three dinuclear Dy-2 complexes. The obtained compounds exhibit excellent thermal stability, ligand-based fluorescence emission, selective adsorption capacity, and typical single-molecule magnetic properties.