Stewart Orlando C, Marwitz Alexander C, Swanson Joel, Bertke Jeffery A, Hartman Tyler, Monteiro Jorge H S K, de Bettencourt-Dias Ana, Knope Karah E, Stoll Sarah L
Department of Chemistry, Georgetown University, Washington, D.C. 20057, United States.
Department of Chemistry, California Polytechnic State University, Humboldt, Arcata, California 95521, United States.
Inorg Chem. 2022 Oct 3;61(39):15547-15557. doi: 10.1021/acs.inorgchem.2c02260. Epub 2022 Sep 16.
The luminescence properties of two divalent europium complexes of the type EuN(SPPh) () and EuN(SePPh) () were investigated. The first complex, EuN(SPPh) (), was found to be isomorphous with the reported structure of complex and exhibited room temperature luminescence with thermochromic emission upon cooling. We found the complex EuN(SePPh) () was also thermochromic but the emission intensity was sensitive to temperature. Both room temperature and low temperature (100 K) single crystal X-ray structural investigation of and indicate geometric distortions of the metal coordination, which may be important for understanding the thermochromic behavior of these complexes. The trivalent europium complex Eu[N(SPPh)] () with the same ligand as was also structurally characterized as a function of temperature and exhibited temperature-dependent luminescence intensity, with no observable emission at room temperature but intense luminescence at 77 K. Variable temperature Raman spectroscopy was used to determine the onset temperature of luminescence of Eu[N(SPPh)] (), where the 615 nm (D → F transition) peak was quenched above 130 K. The UV-visible diffuse reflectance of provides evidence of an LMCT band, supporting a mechanism of thermally activated LMCT quenching of Eu(III) emitting states. A series of ten isomorphous, trivalent lanthanide complexes of type Ln[N(SPPh)] (Ln = Eu () Pr (), Nd (), Sm (), Gd (), Tb ()) and Ln[N(SePPh)] (Ln = Pr (), Nd (, structure was previously reported), Sm (), and Gd () for Q = Se) were also synthesized and structurally characterized. These complexes for Ln = Pr, Nd, Sm, and Tb exhibited room temperature luminescence. This study provides examples of temperature-dependent luminescence of both Eu and Eu, and the use of soft-atom donor ligands to sensitize lanthanide luminescence in a range of trivalent lanthanides, spanning near IR and visible emitters.
研究了两种二价铕配合物EuN(SPPh) ()和EuN(SePPh) ()的发光性质。发现第一种配合物EuN(SPPh) ()与报道的配合物结构同构，并在冷却时表现出室温发光和热致变色发射。我们发现配合物EuN(SePPh) ()也具有热致变色性，但发射强度对温度敏感。对 和 的室温及低温（100 K）单晶X射线结构研究表明金属配位存在几何畸变，这可能对理解这些配合物的热致变色行为很重要。与 具有相同配体的三价铕配合物Eu[N(SPPh)] ()也作为温度的函数进行了结构表征，并表现出温度依赖性发光强度，在室温下无明显发射，但在77 K时发光强烈。变温拉曼光谱用于确定Eu[N(SPPh)] ()发光的起始温度，其中615 nm（D→F跃迁）峰在130 K以上淬灭。 的紫外可见漫反射提供了一个LMCT带的证据，支持了Eu(III)发射态的热激活LMCT淬灭机制。还合成并表征了一系列十个同构的三价镧系配合物Ln[N(SPPh)]（Ln = Eu ()、Pr ()、Nd ()、Sm ()、Gd ()、Tb ()）和Ln[N(SePPh)]（Ln = Pr ()、Nd (，先前已报道结构)、Sm ()、Gd ()，Q = Se）。这些Ln = Pr、Nd、Sm和Tb的配合物表现出室温发光。本研究提供了Eu和Eu温度依赖性发光的实例，以及使用软原子供体配体在一系列三价镧系元素中敏化镧系发光的实例，这些镧系元素涵盖近红外和可见光发射体。
