Lanthanide‐Based Dinuclear Complexes Involving an o‐Quinone–Tetrathiafulvalene–o‐Quinone Bridging Ligand: X‐ray Structures, Magnetic and Photophysical Properties

Abstract

Six dinuclear complexes, [Ln 2 (hfac) 6 (H 2 O) 2 (L)] [Ln = Y (1) and Er (2)], [Yb 2 (hfac) 6 (L)] (3), [Ln 2 (tta) 6 (L)]·3CH 2 Cl 2 [Ln = Y (4) and Er (5)] and [Yb 2 (tta) 6 (L)]·2C 6 H 14 (6), have been prepared by coordination reactions between the [Ln(β-diketonate) 3 ]·2H 2 O (Ln = Y III , Er III and Yb III ; β-diketonate = hfacor tta -) building blocks and 4,4Ј,7,7Ј-tetra-tert-butyl-2,2Ј-bi-1,3benzodithiole-5,5Ј,6,6Ј-tetrone ligand (L), which acts as a bridge between the two metal centres. Their X-ray structures reveal that the symmetries around the lanthanide atoms depend on the β-diketonate anions and the size of the 4f ions. The dc magnetic measurements showed paramagnetic behaviour with thermal variations of the χ M T products that depend on the crystal-field symmetry around the 4f ions. The photophysical properties of the coordination complexes were studied by solid-state absorption spectroscopy, and DFT calculations were carried out on the free ligand L and the dia-Eur.

Magnetic Slow Relaxation in a Metal–Organic Framework Made of Chains of Ferromagnetically Coupled Single‐Molecule Magnets

“…Dy can be described as a “pure 4f” analog of 2d–3d, 3d–3d“, 3d–5d, or 4f–5d heterometallic chains. The strong anisotropy of the Dy‐MBBs and the magnetic couplings in Dy preclude the occurrence of AF order as observed for some SCMs . Ferromagnetic couplings between the MBBs suppress the thermally independent relaxation pathways.…”

Compactly Fused o‐Quinone‐Extended Tetrathiafulvalene‐o‐Quinone Triad – a Redox‐Amphoteric Ligand

“…Unfortunately, the poor solubility of 3 does not allow a thorough study of the solvatochromic effects. Taking into account the properties of the recently described triad 1 ,10,11 the most important band in the spectrum of 4 can be assigned to a donor–acceptor charge transfer. As the p ‐phenylene‐extended unit in 4 is a better donor, this band is redshifted compared to the band observed for 1 (545 nm in CHCl 3 ).…”

“…We previously reported the synthesis of the fused acceptor–donor–acceptor (A–D–A) triad 1 , in which the tetrathiafulvalene (TTF) donor moiety acts as a bridge between two sterically hindered acceptor o ‐quinone units 10. Recently, a number of dinuclear complexes containing 1 as a ligand have been described 9,11. Some of these complexes exhibit unusual and promising luminescence and molecular magnetism.…”

Field-Induced Dysprosium Single-Molecule Magnet Involving a Fused o-Semiquinone-Extended-Tetrathiafulvalene-o-Semiquinone Bridging Triad

“…SMMs or luminescence using the 4,4′,7,7′-tetra-tert-butyl-2,2′-bi-1,3-benzodithiole-5,5′,6,6′-tetrone triad [19,20]. Along these lines, we proposed to replace the TTF core with p-phenylene-extended TTF to lower the HOMO-LUMO gap, because the first oxidation potential is lower than for TTF [21], and to stabilize the protonated semiquinone form, which might offer a dissymmetric coordination site and thus give the possibility to reach new molecular systems.…”

“…The resulting donor (D)-acceptor (A) dyads or A-D-A triads (where D refers to TTF and A refers to quinone) open the route for potential applications in molecular electronics and optoelectronics because of their low highest occupied molecular orbital to lowest unoccupied molecular orbital (HOMO-LUMO) gap [18]. A few Inorganics 2018, 6, 45 2 of 9 years ago, some of the current authors elaborated upon dinuclear complexes that displayed SMMs or luminescence using the 4,4 ,7,7 -tetra-tert-butyl-2,2 -bi-1,3-benzodithiole-5,5 ,6,6 -tetrone triad [19,20].…”