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Wide-Range UV-to-Visible Excitation of Near-Infrared Emission and Slow Magnetic Relaxation in LnIII(4,4′-Azopyridine-1,1′-dioxide)[CoIII(CN)6]3– Layered Frameworks
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2018-12-19 00:00:00 , DOI: 10.1021/acs.inorgchem.8b02096
Szymon Chorazy 1 , Mikolaj Zychowicz 1 , Shin-ichi Ohkoshi 2 , Barbara Sieklucka 1
Affiliation  

Trivalent lanthanide ions combined with two molecular linkers, organic 4,4′-azopyridine-1,1′-dioxide (apdo), and inorganic hexacyanidocobaltate(III), gave a series of magnetoluminescent coordination polymers, [{LnIII(apdo)(H2O)4}{CoIII(CN)6}]·2H2O (Ln = Nd, 1; Tb, 2; Dy, 3; Er, 4; Tm, 5; Yb, 6). They are hybrid organic–inorganic layered frameworks composed of cyanido-bridged {Ln2(μ-NC)4Co2} squares linked by Ln–apdo–Ln bridges into a coordination network of a mixed 4- and 8-metal ring topology. Lanthanide(III) complexes, [LnIII(μ-apdo)2(H2O)4(μ-NC)2]+, of a distorted dodecahedral geometry are isolated by diamagnetic [CoIII(CN)6]3– and apdo linkers. As a result, 16 reveal field-induced slow relaxation of magnetization, with typical temperature-dependent relaxation of a single-ion origin for NdIII-containing 1, DyIII-containing 3, and YbIII-containing 6. The related alternate-current magnetic data were precisely analyzed, indicating the multiple magnetic relaxation pathways, including a direct process, strong quantum tunneling of magnetization, non-negligible Raman processes, and crucial two-phonon Orbach thermal relaxation. The thermal energy barriers of the Orbach process, ΔE/kB, are 15.1(9) K with τ0 = 9.8(9) × 10–6 s at Hdc = 4500 Oe, 16.1(8) K with τ0 = 9.0(9) × 10–5 s at Hdc = 1500 Oe, and 17.3(6) K with τ0 = 3.2(7) × 10–6 s at Hdc = 700 Oe, for 1, 3, and 6, respectively, proving the single-molecule magnet (SMM) behavior. Because of the presence of [Co(CN)6]3–, 16 show strong UV absorption, while the chromophoric apdo leads to the strong absorption in the visible range. As a result, the visible 4f/3d metal-centered emission is quenched, but the near-infrared luminescence from NdIII and YbIII is observed in 1 and 6, respectively. It is realized by Co-to-Ln metal-to-metal, and apdo-to-Ln ligand-to-metal energy transfers; thus, broad UV-to-visible excitation can be explored. Compounds 16 form a novel family of functional bimetallic assemblies, incorporating NIR-emissive SMMs as presented for NdCo (1) and YbCo (6) derivatives.

中文翻译:

Ln III(4,4'-偶氮吡啶-1,1'-二氧化物)[Co III(CN)6 ] 3–层状框架中的近红外发射和慢磁弛豫的大范围紫外可见可见光激发

三价镧系离子与两个分子接头有机4,4'-偶氮吡啶-1,1'-二氧化物(apdo)和无机六氰基钴酸酯(III)结合,得到了一系列的磁致发光配位聚合物,[{Ln III(apdo)( H 2 O)4 } {Co III(CN)6 }]·2H 2 O(Ln = Nd,1 ; Tb,2 ; Dy,3 ; Er,4 ; Tm,5 ; Yb,6)。它们是由氰基桥联的{Ln 2(μ-NC)4 Co 2}由Ln–apdo–Ln桥链接的正方形成为混合的4和8金属环形拓扑的协调网络。十二面体几何形状扭曲的镧系元素[Ln III(μ-apdo)2(H 2 O)4(μ-NC)2 ] +通过抗磁性[Co III(CN)6 ] 3–和-分离。 apdo链接器。其结果,1 - 6揭示了磁化的电场诱导慢松弛,与钕的单离子源的典型依赖于温度的松弛III1,DY III3和YbIII 6。精确分析了相关的交流磁数据,表明了多种磁弛豫路径,包括直接过程,强磁化量子隧穿,不可忽略的拉曼过程以及至关重要的两声子Orbach热弛豫。该过程奥巴赫,Δ的热能障碍ë / ķ,是15.1(9)K与τ 0 = 9.8(9)×10 -6 s的ħ DC = 4500奥斯特,16.1(8)K与τ 0 = 9.0(9)×10 -5 s的ħ DC = 1500奥斯特,和17.3(6)K与τ 0 = 3.2(7)×10 -6 s的ħ DC = 700奥斯特,为13,和6,分别,证明了单分子磁体(SMM)的行为。因为存在的[Co(CN)6 ] 3-1 - 6显示出强的UV吸收,同时所述发色APDO导致在可见光范围内的强吸收。结果,可见的以4f / 3d为中心的金属发射被淬灭,但是在16中观察到了Nd III和Yb III的近红外发光。, 分别。它是通过Co-to-Ln金属到金属以及apdo-Ln配体到金属的能量转移来实现的。因此,可以探索广泛的紫外线到可见光的激发。化合物1 - 6形式的新家族的功能性的双金属组件,结合NIR发射的SMM对提交NDCO(1)和YBCO(6)的衍生物。
更新日期:2018-12-19
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