A Photochromic Molecule-Based Magnet

Abstract

A molecule-based magnet of formula (SP)MnCr(ox) 3 ‚H 2 O has been synthesized, where SP + stands for a new N-methylated pyridospiropyran cation and ox 2represents the oxalate anion. The compound orders ferromagnetically at 5.5 K and exhibits crystalline-state photochromism. The main spectrokinetic data of the UV-induced open form of SP + are strongly modified in (SP)MnCr(ox) 3 ‚H 2 O as compared to those found in (SP)I. The reversible photoreaction of SP + does not modulate the critical temperature of the long-range ferromagnetic order in (SP)MnCr(ox) 3 ‚H 2 O but modifies in a significant way its hysteresis loop.

Multifunctional Magnetic Materials Obtained by Insertion of a Spin‐Crossover FeIII Complex into Bimetallic Oxalate‐Based Ferromagnets

“…Furthermore, the phenoxy rings from [Fe(sal 2 -trien)] + complexes that belong to different double chains that are not involved in these interactions present short contacts with O atoms from the oxalate network (d C16-O14 = 3.384(6) ). Finally, there are short contacts between C atoms from ethylene groups of sal 2 -trien and the oxalate ligands (d C10-O13 = 3.152 (6) [17] and are in full agreement with the magnetic measurements and Mçssbauer spectroscopy (see below), which indicate that all Fe are LS at 180 K (the temperature at which the crystal structure has been determined). On the other hand, the dichloromethane molecules occupy the holes situated in between the [Fe(sal 2 + cations and solvent molecules occupying the cavities (Figure 3).…”

“…In contrast to 2 and 3, it is possible to distinguish between Mn and Cr ions of this oxalate network. Thus, there are two crystallographically independent Mn ions (Mn1 and Mn2) with Mn À O bond lengths that lie between 2.151(6) and 2.196(6) and two crystallographically independent Cr ions (Cr1 and Cr2) with Cr À O bond lengths that lie between 1.957(6) and 1.988 (6) . These are typical Cr III À O and Mn II À O distances similar to those found in other oxalate networks.…”

“…In these compounds, the cooperative magnetism of the oxalate network can coexist with the electronic properties provided by the cationic molecular lattice. Some illustrative examples of this concept are provided by the use of paramagnetic decamethylferrocenium [3] or organic radical cations, [4] photochromic molecules, [5] nonlinear optical (NLO)-active molecules, [6] organic p-electron donors, [7] and chiral The magnetic properties and Mçss-A C H T U N G T R E N N U N G bauer spectroscopy of 1 and 2 indicate that these compounds undergo a longrange ferromagnetic ordering at around 5 K and a spin crossover of the intercalated [Fe(sal 2 …”

Recent Advances on Anilato-Based Molecular Materials with Magnetic and/or Conducting Properties

“…In the last 20 years many efforts have been addressed to add in these materials a further physical property by playing with the functionality of the A + cations located between the bimetallic layers. This strategy produced a large series of multifunctional molecular materials where the magnetic ordering of the bimetallic layers coexists or even interacts with other properties arising from the cationic layers, such as paramagnetism [2,[76][77][78][79][80], non-linear optical properties [2,81,82], metal-like conductivity [83,84], photochromism [2,81,85,86], photoisomerism [87], spin crossover [88][89][90][91][92][93], chirality [94][95][96][97], or proton conductivity [2,98,99]. Moreover, it is well-established that the ordering temperatures of these layered magnets are not sensitive to the separation determined by the cations incorporated between the layers, which slightly affects the magnetic properties of the resulting hybrid material, by emphasizing its 2D magnetic character [2,[75][76][77][78][79][80]95,100,101].…”

Photo-Control of Magnetization by Photochromic Compounds

“…Yu et al reported a photochromic molecule-based magnetic materials with alternating ferromagnetic layer [MnCr(ox) 3 ] n nÀ and cationic spiropyran layer. 37,38 UV light illumination transformed the initially very soft magnet into a much harder one, as evidenced by the dramatic and irreversible changes in the shape of hysteresis loop, although the change is irreversible. A spectacular change in the hysteresis loop was ascribed to photoinduced defects in the crystal structure through the photoreaction of a spiropyran derivative.…”