Two Pairs of Chiral “Tower‐Like” Ln₄Cr₄ (Ln=Gd, Dy) Clusters: Syntheses, Structure, and Magnetocaloric Effect

Abstract

Two pairs of novel chiral chromium lanthanide compounds, formulated as l- and d-[Gd Cr (IN) (μ -OH) (μ -O) (H O) ]⋅[IN] ⋅8 H O (1 and 3), and l- and d-[Dy Cr (IN) (μ -OH) (μ -O) (H O) ]⋅[IN]⋅1.5 H O (2 and 4) (HIN=isonicotinic acid) have been successfully synthesized and characterized. Structural analysis reveals that four Ln ions and four Cr ions connect with each other and yield a "tower-like" [Ln Cr ] skeleton. Apart from the above featuring an aesthetically charming structure, circular dichroism (CD) spectra confirm that compounds 1 and 3, 2 and 4 are enantiomers. To the best of our knowledge, these are the largest chiral chromium lanthanide compounds. In addition, magnetic interaction shows that Gd (the mixture of 1 and 3) exhibits significant cryogenic magnetocaloric effect (MCE) with -ΔS =18.08 J kg K (34.69 mJ cm K ). Also, the observed second-harmonic generation efficiencies of [Gd Cr (IN) (μ -OH) (μ -O) (H O) ]⋅[IN] ⋅8 H O and [Dy Cr (IN) (μ -OH) (μ -O) (H O) ]⋅[IN]⋅1.5 H O are 0.3 and 0.4 times that of urea, respectively.

Barium(II)–Chromium(III) Coordination Polymers Based on Dimethylmalonate Anions: Synthesis, Crystal Structure, Magnetic Properties, and EPR Spectra

“…[ 1 ] In addition, these compounds are capable of showing a large magnetocaloric effect (MCE) – a phenomenon, in which the temperature of a material decreases due to the application of an external magnetic field under adiabatic conditions. [ 2 ] Some Cr III complexes exhibit interesting photophysical and photochemical properties and can be used, for example, as dyes for solar cells, sensitizers for conversion processes, photochemical sources of nitric oxide NO, and photoredox catalysts. [ 3 ] Chromium(III) compounds have catalytic activity in the oligomerization and polymerization of ethylene and its derivatives, [ 4a,4b ] copolymerization of various substrates, [ 4c,4d ] and glucose conversion.…”

Chirality and Magnetic Properties of One‐dimensional Ln (Ln = Gd, Dy) Polymers

“…Products Dy‐ L and Dy‐ D exposed four Cotton effects at about 255, 260, 278 nm from 250 to 400 nm. Meanwhile, the CD spectra of Gd‐ L and Gd‐ D were also investigated (Figure ), the solid CD spectra of compound Gd‐ L and Gd‐ D are mirror image inversion, indicating Gd‐ L and Gd‐ D are a pair of enantiomers . Products Gd‐ L and Gd‐ D exposed four Cotton effects at about 255, 264, 270 nm from 250 to 400 nm.…”

“…To the best of our knowledge, lanthanide ions own the individual 4f electronic structures, resulting high and changing coordination numbers, large magnetic effects and so on, which is favored for the potential applications in magnetic fields, etc , . For example, Gd 3+ ion owns characteristic f 7 election framework and negligible magnetic anisotropy has been widely researched and regarded as a remarkable candidate for molecular magnetic refrigerant materials such as Gd 60 with –Δ S max = 48 J · kg –1 · K –1 and Gd 140 with –Δ S max = 38 J · kg –1 · K –1 , …”

“…Nevertheless, the obvious drawback of the first method is the costly chiral ligand , . (ii) based on the achiral ligands to obtain chiral products . Great progress has been realized in chiral lanthanide‐based compounds by achiral ligands, bringing low consumption of chiral compounds closer to actuality …”

Icosahedron [Cl12]12- Templated Gigantic Gd158Co38 Nanocluster with the Largest Ln158 Core for Magnetic Cooling

“…Synthesis and structural characterization of giant molecules have long been one of the most attractive elds, owing to their fascinating topological structures, complex intramolecular assembly behavior, and numerous physical-chemical properties different from small molecules [1][2][3][4][5][6][7][8][9][10] . High-nuclearity lanthanide(Ln)-containing clusters are one of the new members of the giant molecular family and has received extensive attention in the past decade associated with charming structures and excellent properties in magnetism, catalysis, and luminescence [11][12][13][14][15][16][17][18][19][20] .…”