Arauzo A, Gasque L, Fuertes S, Tenorio C, Bernès S, Bartolomé E
Servicio de Medidas Físicas. Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain and Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, Zaragoza, Spain.
Facultad de Química, Universidad Nacional Autónoma de México, Avenida Universidad 3000, CDMX 04510, Mexico.
Dalton Trans. 2020 Oct 12;49(39):13671-13684. doi: 10.1039/d0dt02614j.
Coumarin-based lanthanide complexes of general formula [Ln(coum)3(phen)(H2O)x]·yH2O (Ln-phen, x = 0,1, 0 ≤ y ≤ 1.5; phen = 1,10-phenanthroline; coum = 3-acetyl-4-hydroxylato-coumarin; Ln = Eu, Tb, Dy, Tm) and [Ln(coum)3(batho)]·0.7EtOH (Ln-batho, batho = 4,7-diphenyl-1,10-phenanthroline; Ln = Eu, Tb, Dy, Tm) were synthesized. The magnetic relaxation and photoluminescence behavior of these complexes was compared with that of the related compounds [Ln(coum)3(EtOH)(H2O)]·EtOH (Ln-coum), so as to investigate the effects of incorporating a second chromophore, either the phen or batho ligand, to the original coordination scaffold, provided with three coumarin (coum) ligands. Slow relaxation of the magnetization under H = 0 with moderate activation energies was observed for the Dy-phen (U/kB = 99.1 K) and Dy-batho (U/kB = 67.1 K) compounds, whereas Tb analogues presented field-induced single molecule magnet (SMM) behavior, with U/kB = 11.7 K (16.6 K@3 kOe) for Tb-phen (Tb-batho), respectively. Luminescent emission in the visible range was observed for all the Ln-coumarin based compounds upon ligand sensitization, with high quantum yields of 45 (40%) for Eu-phen (Eu-batho) compounds and 65-76-58% for Tb-coum, phen, batho analogues. Sensitization is mainly provided by the coumarin ligand having the energy difference ΔE between its triplet state T1 and the lanthanide emitting level closest to the optimum, while the second ligand can play either a synergistic or competing sensitizing role. The Tb-phen/batho compounds presented simultaneously SMM and luminescent behavior, with excellent values of the bifunctional figure of merit (ηSMM-QY ∼ 1000% K). The reported compounds represent a new class of bifunctional materials with potential interesting application in various fields.
合成了通式为[Ln(coum)3(phen)(H2O)x]·yH2O（Ln-phen，x = 0,1，0 ≤ y ≤ 1.5；phen = 1,10-菲咯啉；coum = 3-乙酰基-4-羟基香豆素；Ln = Eu、Tb、Dy、Tm）和[Ln(coum)3(batho)]·0.7EtOH（Ln-batho，batho = 4,7-二苯基-1,10-菲咯啉；Ln = Eu、Tb、Dy、Tm）的基于香豆素的镧系配合物。将这些配合物的磁弛豫和光致发光行为与相关化合物[Ln(coum)3(EtOH)(H2O)]·EtOH（Ln-coum）的行为进行了比较，以研究在具有三个香豆素（coum）配体的原始配位骨架中引入第二个发色团（即phen或batho配体）的影响。对于Dy-phen（U/kB = 99.1 K）和Dy-batho（U/kB = 67.1 K）化合物，在H = 0时观察到具有中等活化能的磁化缓慢弛豫，而Tb类似物表现出场诱导单分子磁体（SMM）行为，Tb-phen（Tb-batho）的U/kB分别为11.7 K（16.6 K@3 kOe）。基于Ln-香豆素的所有化合物在配体敏化后均观察到可见光范围内的发光发射，Eu-phen（Eu-batho）化合物的量子产率高达45%（40%），Tb-coum、phen、batho类似物的量子产率为65 - 76 - 58%。敏化主要由香豆素配体提供，其三重态T1与最接近最佳值的镧系发射能级之间存在能量差ΔE，而第二个配体可以发挥协同或竞争敏化作用。Tb-phen/batho化合物同时呈现SMM和发光行为，双功能品质因数（ηSMM-QY ∼ 1000% K）的值优异。所报道的化合物代表了一类新型的双功能材料，在各个领域具有潜在的有趣应用。
