The Stepwise Formation of {Gd₄} Clusters with Magnetocaloric Effect, Accompanied by In Situ Condensation Cyclization Reactions

Abstract

Accompanied by condensation cyclization reactions in solvothermal conditions, three Gd(III) tetranuclear clusters {[Gd4(L x )2(μ3-OH)2(NO3)2(Ac)6]} (x = 1, 2, and 3 for 1, 2, and 3, respectively) were isolated and characterized, wherein, L1–3 were in situ synthesized from bis[3-(pyridin-2-yl)-1H-1,2,4-triazole-5-yl]methane (bptm), 5-bptm (bis[3-(5-methylpyridin-2-yl)-1H-1,2,4-triazole-5-yl]methane), and 4-bptm (bis[3-(4-methylpyridin-2-yl)-1H-1,2,4-triazole-5-yl]methane) in the presence of GdIII ions, respectively. The step-by-step formation process (bptm → L1 → Gd1(L1)1 → Gd2(L1)1 → Gd2(L1)2 → Gd3(L1)2 → Gd4(L1)2) of the tetranuclear clusters in 1 was tracked by mass spectrometry technology. The study of their magnetic properties showed that 1–3 displayed significant magnetocaloric effects with the −ΔS m values of 29.25–29.64 J K–1 kg–1.

Two Octa-Nuclear {Ln8} (Ln = Tb, Dy) Complexes with “4 + 4” Covalent Organic Macrocycles: Structure, Solution Behavior, Luminescence, and Magnetic Properties

“…The bond lengths of Tb–O/Tb–N were 2.235–2.808 and 2.416–2.485 Å, respectively (the bond lengths of Dy–O/Dy–N in Dy 8 L 4+4 were 2.234–2.900 Å and 2.427–2.472 Å, respectively; Tables S1–S4). The coordination environment of eight Tb 3+ ions was not the same. Five Tb 3+ ions were in eight-coordination mode, and the coordination atoms (one N and seven O atoms) originated from two CH 3 COO – anions and L 4+4 ligands formed a Muffin.…”

“…S1−S4). 28 The coordination environment of eight Tb 3+ ions was not the same. Five Tb 3+ ions were in eight-coordination mode, and the coordination atoms (one N and seven O atoms) originated from two CH 3 COO − anions and L 4+4 ligands formed a Muffin.…”

Structural Evolution and Properties of Praseodymium Antimony Oxochlorides Based on a Chain-like Tertiary Building Unit

“…Metal–oxo cluster-based crystalline compounds have attracted increasing attention for their intriguing structural characteristics and properties [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. Various types of metal–oxo clusters with tunable composition, size, and symmetry, such as polyoxometalate cluster [ 16 , 17 , 18 ], 3d–4f oxide cluster [ 19 , 20 ], and lanthanide oxide cluster [ 21 , 22 ], have been developed as SBUs to construct cluster-based crystals with complex structures. We have reported the first discrete lanthanide antimony nanocluster of [Pr 4 Sb 12 O 18 Cl 17 ] 5− (denoted as {Pr 4 Sb 12 }) with T d symmetry and 12 terminally coordinated Cl − ions as antennas in the cluster [ 23 ].…”