A new Gd3+ coordination polymer (CP), namely, poly[diaqua[μ4-1′-carboxy-3,3′-(diazene-1,2-diyl)dibenzene-1,2,2′-tricarboxylato]gadolinium(III)], [Gd(C16H7N2O8)(H2O)2]
n
, (I), has been synthesized hydrothermally from Gd(NO3)3·6H2O and azobenzene-2,2′,3,3′-tetracarboxylic acid (H4abtc). The target solid has been characterized by single-crystal and powder X-ray diffraction, elemental analysis, IR spectroscopy and susceptibility measurements. CP (I) crystallizes in the monoclinic space group C2/c. The structure features a 4-connected topology in which Gd3+ ions are connected by carboxylate groups into a linear chain along the monoclinic symmetry direction. Adjacent one-dimensional aggregates are bridged by Habtc3− ligands to form a two-dimensional CP in the (10\overline1}) plane. A very short hydrogen bond [O...O = 2.4393 (4) Å] links neighbouring layers into a three-dimensional network. A magnetic study revealed antiferromagnetic Gd...Gd coupling within the chain direction. CP (I) displays a significant magnetocaloric effect (MCE), with a maximum −ΔS
m of 27.26 J kg−1 K−1 for ΔH = 7 T at 3.0 K. As the MCE in (I) exceeds that of the commercial magnetic refrigerant GGG (Gd3Ga5O12, −ΔS
m = 24 J kg−1 K−1, ΔH = 30 kG), CP (I) can be regarded as a potential cryogenic material for low-temperature magnetic refrigeration.
一种新的 Gd3+ 配位聚合物 (CP),即聚[二夸父[μ4-1′-羧基-3,3′-(重氮-1,2-二基)二苯-1,2,2′-三羧基]钆(III)],[Gd(C16H7N2O8)(H2O)2] n
n
由 Gd(NO3)3-6H2O 和偶氮苯-2,2′,3,3′-四羧酸 (H4abtc) 水热合成。目标固体已通过单晶和粉末 X 射线衍射、元素分析、红外光谱和电感测量进行了表征。CP (I) 在单斜空间群 C2/c 中结晶。其结构具有 4 连接拓扑,其中 Gd3+ 离子通过羧酸基沿着单斜对称方向连接成线性链。相邻的一维聚集体由 Habtc3- 配体桥接,在 (10\overline1}) 平面上形成二维 CP。一个非常短的氢键[O...O = 2.4393 (4) Å]将相邻层连接成一个三维网络。磁性研究揭示了链方向上的反铁磁性钆...钆耦合。CP (I) 具有显著的磁致效应(MCE),最大 -ΔS
m 为 27.26 J kg-1 K-1,ΔH = 7 T,温度为 3.0 K。由于 (I) 中的 MCE 超过了商用磁性制冷剂 GGG(Gd3Ga5O12,-ΔS
m = 24 J kg-1 K-1, ΔH = 30 kG),因此 CP (I) 可被视为一种潜在的低温磁制冷材料。