Redox Modulation of Field-Induced Tetrathiafulvalene-Based Single-Molecule Magnets of Dysprosium

Abstract

The complexes [Dy2(tta)6(H2SQ)] (Dy-H2SQ) and [Dy2(tta)6(Q)]·2CH2Cl2 (Dy-Q) (tta− = 2-thenoyltrifluoroacetonate) were obtained from the coordination reaction of the Dy(tta)3·2H2O units with the 2,2′-benzene-1,4-diylbis(6-hydroxy-4,7-di-tert-butyl-1,3-benzodithiol-2-ylium-5-olate ligand (H2SQ) and its oxidized form 2,2′-cyclohexa-2,5-diene-1,4-diylidenebis(4,7-di-tert-butyl-1,3-benzodithiole-5,6-dione (Q). The chemical oxidation of H2SQ in Q induced an increase in the coordination number from 7 to 8 around the DyIII ions and by consequence a modulation of the field-induced Single-Molecule Magnet behavior. Computational results rationalized the magnetic properties of each of the dinuclear complexes.

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

“…Moreover, when chirality is added to the (luminescent) SMM behavior [21][22][23][24][25][26][27][28], chiral SMM [29], ferroelectric SMM [30] as well as chiral luminescent SMM [31][32][33][34][35][36] and magneto-chiral SMM [37,38] can be obtained. To these three properties, the introduction of redox-active ligands is of interest because it could permit to switch both optical and magnetic properties depending on the oxidation state of the ligand [39][40][41][42][43][44][45][46]. One of the most used redox-active ligands is made from the tetrathiafulvalene (TTF) core because of its two mono radical and dicationic stable states which are easily accessible by chemical ways and because it can be easily decorated with one to four substituted groups able to coordinate transition metal and lanthanide ions [18,[47][48][49].…”

Annulation of a 1,3-dithiole ring to a sterically hindered o-quinone core. Novel ditopic redox-active ligands

“…o-Dioxolene redox-active species bearing additional functions are regarded as promising ligands for the synthesis of metallocomplexes exhibiting unusual magnetic, photovoltaic or luminescent properties. Thus, previously reported binuclear rare-earth metal complexes with redox-active triads such as o-quinonetetrathiafulvalene-o-quinone and o-quinone-(p-phenylene extended tetrathiafulvalene)-o-quinone were found to display switching SMM [4][5][6][7] or unique luminescent properties [8].…”

Field-Induced Single-Molecule Magnets of Dysprosium Involving Quinone Derivatives

“…Organic radical semiquinone form is often associated to transition metal to design complexes displaying chemical and physical properties, such as valence tautomerism [4], photo-and thermo-mechanical effects [5]. o-Quinone-like dioxolenes in quinone, semiquinone [6][7][8][9] or catecholate [10][11][12] oxidation states have been associated with lanthanide ions to generate luminescence [13] and single-molecule magnet (SMM) behavior [14][15][16], as well as magnetic or optical switching [17][18][19][20]. It is worth mentioning that SMM behavior is associated to the observation of slow magnetic relaxation at the molecular scale, leading to the opening of a hysteresis loop at low temperature.…”