Chiral or Luminescent Lanthanide Single-Molecule Magnets Involving Bridging Redox Active Triad Ligand

Abstract

The reactions between the bis(1,10-phenantro[5,6-b])tetrathiafulvalene triad (L) and the metallo-precursors Yb(hfac)3(H2O)2 (hfac− = 1,1,1,5,5,5-hexafluoroacetylacetonato anion) and Dy(facam)3 (facam− = 3-trifluoro-acetyl-(+)-camphorato anion) lead to the formation of two dinuclear complexes of formula [Yb2(hfac)6(L)]·2(C7H16) ((1)·2(C7H16)) and [Dy2((+)facam)6(L)]·2(C6H14) ((2)·2(C6H14)). The X-ray structures reveal that the L triad bridges two terminal Yb(hfac)3 or Dy(facam)3 units. (1)·2(C7H16) behaved as a near infrared YbIII centered emitter and a field-induced Single-Molecule Magnet (SMM) while (2)·2(C6H14) displayed SMM behavior in both zero- and in-dc field. The magnetization mainly relaxes through a Raman process for both complexes under an optimal applied magnetic field.

One- and Two-Electron Redox Catalysis with Lutetium Enabled by a Tris(Amido) Redox-Active Ligand

“…There has been a growing interest in exploring redox-active ligands with lanthanides and actinides because of the novel properties that these complexes exhibit. − In particular, these complexes have applications as luminescent sensors/probes, in materials chemistry (e.g., coordination polymers, metal–organic frameworks and molecular magnets), and even in medicinal chemistry (e.g., Xcytrin, a Gd-based drug for cancer therapy that contains a texaphyrin redox-active ligand). − Redox-active ligands have also been employed for the electro-kinetic separation of lanthanides . In addition, Ln and An complexes with redox-active ligands display a myriad of reactivity ranging from redox isomerism, heterobimetallic reactivity, CO 2 reduction as well as oxidation and reduction reactions with inorganic (e.g., S 8 , Se 0 ) and organic (e.g., alkyl iodides) substrates. − Redox-active ligands are also known to promote reductive elimination from An complexes as demonstrated by the radical reductive elimination of bibenzyl from UBn 4 via the coordination of iminoquinone or α-diimine redox-active ligands. − …”

Optical Phenomena in Molecule-Based Magnetic Materials

“…Further efforts concerned the introduction and modification of luminescent properties of these complexes, which was realized in two ways: (i) by modifying the acac ligand or (ii) by replacing coordinated water molecules with appropriate auxiliary antenna ligands (Figure ). − In this regard, the acac molecules can be modified with strong electron-withdrawing trifluoromethyl groups which was shown to improve the Ln III -centered luminescence. The resulting complexes of the [Ln III (hfac) 3 (H 2 O) 2 ] (hfac = hexafluoro­acetylacetonate) composition were used to prepare {[Dy III (hfac) 3 (pyNO)] 2 } (pyNO = pyridine N -oxide) derivatives showing remarkable SMM behavior and metal-based luminescence with a quantum yield of 0.1% .…”

“…Schematic representation of the routes for structural modifications of luminescent [Dy III (acac) 3 (H 2 O) 2 ] (acac = acetylacetonate) complexes, realized in two ways, by modifying the acac ligand or coordinating additional antenna ligands with the electron donating ability (tfac = 1,1,1-trifluoro­acetylacetonate; hfac = hexafluoro­acetylacetonate; 9Accm = 1,7-di-9-anthracene-1,6-heptadiene-3,5-dione; tta = 2-thenoyltrifluoro­acetonate; facam = 3- trifluoroacetyl-(+)-camphorate anion; 2,2′-bpym = 2,2′-bipyrimidine; 2,2′-bpy = 2,2′-bipyridine; py = pyridine; TTF-L1, TTF-L2, TTF-L3 = three types of tetrathiafulvalene-based ligands). − The key modification parts were indicated by the darker color.…”

“…Implementation of chirality into single-molecule magnets (SMMs) was also realized in multimetallic coordination clusters molecules − as well as mononuclear complexes. ,,− In most cases, a straightforward strategy relying on the usage of chiral ligands was explored. For instance, in the cluster-type SMMs, by replacing acetate ligand with ( R )/( S )-chloropropionate, classical {Mn III/IV 12 } nanomagnets turn into a pair of chiral ones showing the opposite Cotton effects in the CD spectra .…”

Chiral Zn3Ln3 Hexanuclear Clusters of an Achiral Flexible Ligand

“…Single-molecule magnets (SMMs) have been widely investigated for their potential applications in high-density information storage and molecular spintronic devices. , From transition metals to lanthanide elements, − SMMs have developed abundantly and variously, including high-performance SMMs, − fluorescent SMMs, − chiral SMMs, and so on. However, the preparation of chiral SMMs often faces the difficulties of crystal racemization or solution racemization.…”