Heterometallic Mixed3d-4fMetallacrowns: Structural Versatility, Luminescence, and Molecular Magnetism

Synthesis, Structural, and Magnetic Characterization of a Mixed 3d/4f 12-Metallacrown-4 Family of Complexes

“…Heterometallic 3d/4f complexes continue to attract the interest of the scientific community as they have been proven to be good candidates for possible applications in various fields such as optics [1,2], catalysis [3], and molecular magnetism [4]. In the field of molecular magnetism, the use of paramagnetic 3d metal ions in combination with highly anisotropic lanthanides such as Dy III or Tb III with large and unquenched orbital angular momenta [5] can lead to single-molecule magnetism (SMM) behavior with large anisotropy barriers (or energy barriers) for the magnetization reversal.…”

“…The first example of a 12-MC-4 was reported in 1989 by Pecoraro and Lah, and it was a Mn(OAc) 2 [12-MC-MnIII(N)shi -4] complex where OAc − is acetate ions and shi 3− is salicylhydroximate ions [13]. Pecoraro and coworkers have exceedingly demonstrated that salicylhydroxamic acid (shaH 2 , Scheme 1) can possibly be subjected to a metal-assisted 2-amide-iminol tautomerism, which leads to salicylhydroxime (shiH 3 , Scheme 1); the latter being an excellent chelating-bridging ligand which has also been shown to possess the appropriate geometry to afford the 12-MC-4 motif [1,15]. The formed repeating unit of [Mn III -N-O], along with the triply deprotonated salicylhydroximate, the central Mn II ion and the two acetate bridges were responsible for the aforementioned configuration.…”

“…Usually, in the central MC cavity sits a transition metal ion, even though there are also reports where alkali and alkaline earth metals occupy the cavity [15,16]. Lately, the focus has been turned into the incorporation of lanthanide ions in the center, since these compounds have been proposed as excellent candidates for molecular recognition [17,18], molecular magnetism [19] and luminescent [1,[19][20][21][22] technologies. Single-crystal diffraction studies revealed that compounds 1 and 2 are isostructural and crystallize in the P4/n tetragonal space group, while complex 3 crystallizes in the P4cc tetragonal space group (Table S1).…”

A Unique LnIII{[3.3.1]GaIII Metallacryptate} Series That Possesses Properties of Slow Magnetic Relaxation and Visible/Near‐Infrared Luminescence

“…Since their discovery in 1989, metallacrowns, inorganic structural analogues to crown ethers, have demonstrated a high potential in numerous applications, including host‐guest binding, gas adsorption, molecular magnetism, and lanthanide(III)‐based luminescence . Metallacrowns possess a high degree of tunability based on the choice of ligand and metal, which uniquely allows for the predictable design of complexes towards a specific application . For example, the use of closed shell cations such as gallium(III) and zinc(II) ions has led to the creation and characterization of lanthanide(III) MCs with record‐breaking luminescence properties in molecular materials .…”

“…[9,14,39] Metallacrowns possess ah igh degree of tunability based on the choice of ligand and metal,w hichu niquelya llows for the predictable design of complexes towards as pecific application. [40][41][42][43][44] For example, the use of closed shell cationss uch as gallium(III) and zinc(II) ions has led to the creationa nd characterization of lanthanide(III) MCs with record-breaking luminescence properties in molecular materials. [9,14] Metallacrownsh ave also established a rich history in molecular magnetism, both as 3d-4fb imetallic and as lanthanide(III) complexes.E xaminationo ft hese systems has provided significant insighti nto the magnetic properties of 3d transitionm etals in associationw ith lanthanide(III) ions.…”