Heterodinuclear Cryptates [EuML(dmf)](ClO4)2 (M=Ca, Cd, Ni, Zn): Tuning the Luminescence of Europium(III) through the Selection of the Second Metal Ion

Abstract

Four heterodinuclear cryptates [EuML(dmf)](ClO4)2 (M=Ca, Cd, Ni, Zn) were synthesized by a two‐step method (L denotes deprotonated anionic cryptand synthesized by condensation of tris(2‐aminoethyl)amine with 2,6‐diformyl‐4‐chlorophenol). The ES‐MS spectra of the four cryptates and the crystal structure of [EuNiL(dmf)](ClO4)2⋅MeCN confirm that a strict dinuclear EuIII–MII entity exits in the cryptates. The cyclic voltammetry and luminescence spectral investigations indicate that the introduction of second metal ions into the mononuclear EuIII cryptate result in a negative shift of the redox potential of EuIII and a change in luminescence intensity of EuIII. The cryptate [EuML(dmf)](ClO4)2 was shown to quench the emission of EuIII when M=Ni and to enhance the emission of EuIII when M=Ca, Cd, and Zn in the sequence: mononuclear<Eu–Ca<Eu–Cd<Eu–Zn.

Bond-valence parameters of lanthanides

“…CSD refcode ZOGKOV (Abrahams et al, 1995), BEVXUW (Harder, 2004), XATWOE (Rabe et al, 2000), TEYVIC (Rogers, 1996), RADJIP (Hitchcock et al, 2000), CUWGEG (Evans, Grate et al, 1985)] or the oxidation state is incorrectly assigned. For example, in the CSD the central ion may be assigned as divalent, whereas in the original work it is correctly assigned as trivalent [CSD refcode SMNICD (Moore et al, 1972), KADKEG (Woodman et al, 2003), CUGPEZ (Deacon et al, 1984), EGIMUC (Chen et al, 2002)]. For one Sm III compound in the original work the central atom is given as oxidation state +2 [CSD refcode RELNEB (Hou et al, 1996)].…”

Syntheses, structures and photophysical properties of tetranuclear Cd–Ln coordination complexes

“…18-20 However, reports of luminescent Cd-Ln complexes are rare, and only two relevant papers are published (excluding our studies). 21, 22 One report is about an Eu-Cd cryptate complex that shows the characteristic emission bands of the Eu(III) ion, 23 and the other is a report of a series of luminescent Cd-Ln heterometallic complexes with a 4,5-imidozoledicarboxylic acid ligand which do not emit in the NIR region. 24 The Cd-Ln complexes are hard to synthesize, which may be attributed to the strong coordination ability of the Cd(II) ions.…”

Carboxylate-Decorated Aggregation of Octanuclear Co4Ln4 (Ln = Dy, Ho, Yb) Complexes from Ligand-Controlled Hydrolysis: Synthesis, Structures, and Magnetic Properties

“…The synthesis and inclusive characterization of multinuclear 3d–4f coordination aggregates (CAs) have received considerable attention in recent years. These research endeavors not only have provided new, intricate, and aesthetically pleasing molecular structures but also resulted interesting physical properties and applications. − These 3d–4f CAs are of interest for their expected single-molecule magnet (SMM) behavior to show slow paramagnetic relaxation and hysteresis. − The significant characteristic of the SMM is the presence of an anisotropy-induced blocking barrier that will be able to provide long magnetic relaxation times at elevated temperatures. Such molecular magnets have shown potential in high-density magnetic data storage, spintronics, − quantum computation, − and magnetic refrigeration. − These SMM complexes show a quantum tunneling mechanism which shortcuts the relaxation energy barrier by losing magnetization very quickly.…”