Placing a crown on Dy^III – a dual property Ln^III crown ether complex displaying optical properties and SMM behaviour

Abstract

Two mononuclear Dy III crown ether complexes [Dy(15C5)(H 2 O) 4 ](ClO 4 ) 3 Á(15C5)ÁH 2 O (1) and [Dy(12C4)(H 2 O) 5 ](ClO 4 ) 3 ÁH 2 O (2) have been prepared and characterized. X-ray diffraction studies show that both compounds crystallize as half sandwich type structures with muffin and pseudo-capped square antiprismatic geometries respectively. Despite the comparable local environments of the Dy III ions they display remarkably different dynamic magnetic properties with only 1 displaying SMM properties in zero field. The solid state emission spectra for both 1 and 2 display sharp bands associated with f-f transitions.From the fine structure of the 4 F 9/2 -6 H 15/2 band, the Stark splitting of the 6 H 15/2 ground state permitted the energy difference between the ground and first excited state to be determined. For 1 this value (DE = 58.0 AE 3.0 cm À1 ) is in excellent agreement with ab initio calculations and the experimentally observed SMM behaviour. For 2, the photoluminescence data and theoretical calculations support a less well isolated ground state (DE = 30 AE 3.0 cm À1 ) in which a rapid relaxation process affords no SMM behaviour in zero-field.

Magneto-Luminescence Correlation in the Textbook Dysprosium(III) Nitrate Single-Ion Magnet

“…In this line of scope, luminescent SIMs are particularly appropriate for these investigations since the photo-luminescence measurements permit determining spectroscopically the Stark sub-level structure of the lanthanides ions and comparing it with the magnetic data. However, examples of such magneto-optical correlations are rather scarce [7][8][9][10][11][12][13][14][15][16][17][18] in comparison with the large number of reported lanthanides-based SIMs. This fact is often due to the weak or completely quenched emission in these complexes.…”

“…This confirms that the main source of relaxation is clearly an Orbach process (red dashed line, Figure 5b). This constitutes a rare example of a luminescent SIM without an underestimation of ∆ obtained by magnetism as frequently observed in luminescent SIMs [7][8][9][10][11][12][13][14][15][16][17][18].…”

Study of the influence of magnetic dilution over relaxation processes in a Zn/Dy single-ion magnet by correlation between luminescence and magnetism

“…In such spectral interval, the emission spectra of 1 and 2 are well reproduced by 3 Stark components ascribed to transitions from the lowest 4 F 9/2 Stark sublevel to the two lowest Stark levels of the 6 H 15/2 multiplet (m J ¼ AE15/2 and 13/2). The third transition can be ascribed to an hot band arising from a transition from the rst excited Stark sublevel of the emitting 4 F 9/2 state (located at $55 cm À1 above the low-energy 4 F 9/2 sublevel) 18,26,38 to the corresponding ground Kramers doublet of the 6 H 15/2 multiplet (m J ¼ AE15/2), as illustrated in Fig. 7C and D for 1 and 2, respectively.…”

Magnetic Behavior of Luminescent Dinuclear Dysprosium and Terbium Complexes Derived from Phenoxyacetic Acid and 2,2’-Bipyridine

“…For complex 1, no peak maximum was observed in the out of phase ac susceptibility for a temperature range of 1.85 K-10.87 K (in presence of an oscillating ac field of 3 Oe and frequency range 1-1000 Hz) without an external dc magnetic field ( Figure S3). Now the absence of peak maxima in the out of phase ac susceptibility indicates the fast zero-field quantum tunneling of magnetization (QTM) [45,46]. So to suppress the effect of QTM, ac magnetic susceptibility measurements were performed under several (0 Oe to 3000 Oe) dc magnetic fields at 1.85 K for the frequency range 0.1-1000 Hz ( Figure S4).…”