Single-Molecule-Magnet Behavior and Fluorescence Properties of 8-Hydroxyquinolinate Derivative-Based Rare-Earth Complexes

Abstract

Five tetranuclear rare-earth complexes, [RE4(dbm)4L6(μ3-OH)2] [HL = 5- (4-fluorobenzylidene)-8-hydroxylquinoline; dbm = 1,3-diphenyl-1,3-propanedione; RE = Y (1), Eu (2), Tb (3), Dy (4), Lu (5)], have been synthesized and completely characterized. The X-ray structural analyses show that each [RE4] complex is of typical butterfly or rhombus topology. Each RE(III) center exists in an eight-coordinated square-antiprism environment. Magnetic studies reveal that complex 4 displays single-molecule-magnet behavior below 10 K under a zero direct-current field, with an effective anisotropy barrier (ΔE/kB = 56 K). The fluorescence properties of complexes 1-5 were also investigated. Complexes 2-4 showed their characteristic peaks for the corresponding RE(III) center, while complexes 1 and 5 showed the same emission peaks with the ligand when they were excited at the same wavelength.

Hydroxyquinoline–Calix[4]arene Conjugates as Ligands for Polynuclear Lanthanide Complexes: Preparation, Characterization, and Properties of a Dinuclear EuIII Complex

“…So far four types of structures were encountered: mononuclear Ln(OQ) 3 or Ln(OQ) 4 complexes, trinuclear Ln 3 (OQ) 8 (L′) compounds (e.g., Ln = Yb, L′ = NO 3 – ; Ln = Yb, L′ = CH 3 CO 2 – ), and trinuclear Ln 3 (OQ) 9 species (Ln = Er, Ho, Yb, Dy). Given the unusual magnetic properties of polynuclear lanthanide complexes, it is remarkable that the magnetic properties of only a few hydroxyquinolinolato complexes have been studied , …”

Tetranuclear Lanthanide Complexes Supported by Hydroxyquinoline‐Calix[4]arene‐Ligands: Synthesis, Structure, and Magnetic Properties of [Ln4(H3L)2(µ‐OH)2(NO3)4] (Ln = Tb, Dy, Yb) and [Dy2(H4L)2(NO3)](NO3)

“…This complex contains bridging hydroxyquinolinolato groups and does not exhibit slow magnetic relaxation. [30] For the Dy 3+ complex 4, on the other hand, frequency dependent out-of-phase ac magnetic susceptibilities ( M ′′) are observed in zero and applied DC field ( Figure S18). However, no full peaks are observed, and the data is not sufficient to extract an energy barrier.…”

“…from the above applications, the design of lanthanide-based molecular magnetic materials [22][23][24][25][26][27] utilizing hydroxyquinolinolato ligands has also attracted much interest. [28][29][30][31][32][33] Thus the magnetic properties of several lanthanide complexes supported by HOQ derivatives have been reported in the last five years. [34,35] Recently, we have reported a tert-butyl-calix [4]arene-derived 8-hydroxyquinolinolato ligand (H 6 L), which was found to be a potent extraction agent for some lanthanide [36] and actinide elements (Scheme 1).…”

Novel nanofiber yarns synchronously endued with tri-functional performance of superparamagnetism, electrical conductivity and enhanced fluorescence prepared by conjugate electrospinning

“…Generally, rare earth (RE) complexes have excellent uorescence properties due to the f-f electron transition and thus have applications in sensors, laser materials, solar energy conversion materials, etc. 22,23 Fe 3 O 4 NPs as magnetic materials show great potential for various elds such as magnetic-controlled switches, electronics and biological processes because of their unique superparamagnetism, good biocompatibility and high permeability. 24,25 PANI, as a very popular conductive polymer, has been widely applied in supercapacitor electrodes, electromagnetic shielding materials, and gas sensors on account of the advantages of easy synthesis, low cost, adjustable performance, good environmental stability and tunable high conductivity.…”