Lin Li-Rong, Tang Hui-Hui, Wang Yun-Guang, Wang Xuan, Fang Xue-Ming, Ma Li-Hua
Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, People's Republic of China.
Department of Chemistry, College of Science and Computer Engineering, University of Houston-Clear Lake , 2700 Bay Area Boulevard, Houston, Texas 77058, United States.
Inorg Chem. 2017 Apr 3;56(7):3889-3900. doi: 10.1021/acs.inorgchem.6b02819. Epub 2017 Mar 22.
The coordination ability of ligands functionalized by azobenzene was manipulated, and two novel chelating ligands, (E)-4-(phenyldiazenyl)-N,N-bis(pyridin-2-ylmethyl) benzohydrazide (CHNO, PBPM) and (E)-4-((4-(dimethylamino)phenyl)diazenyl)-N,N-bis(pyridin-2-ylmethyl) benzohydrazide (CHNO, dmPBPM), were synthesized. The ligands can offer four coordinating atoms (one oxygen and three nitrogens) to act as tetradendate ligands, together with the two β-diketonates (4,4,4-trifluoro-1-phenylbutane-1,3-dionate, tfd), and the trifluoroacetate anion presented as a ligand and a counterion to form the quaternary units with lanthanide(III) ions (La, Eu, and Gd), [Ln(tfd)(PBPM)(CFCO)] (LnCHFNO) and [Ln(tfd)(dmPBPM)(CFCO)] (LnCHFNO), where the lanthanide(III) ions are nine coordinated with NO donor sets. All six complexes were structurally characterized, and four crystals were obtained and further analyzed by means of single-crystal X-ray diffraction. They all crystallized in the monoclinic P2/c space group with very similar lattice parameters, forming a monocapped twisted square antiprism. We successfully observed the photoluminescent properties of Eu(III) complexes at a wavelength of 614 nm in both solution and the solid state, as well as the trans-to-cis photoisomerization with the quantum yield (Φ = 10) of [Eu(tfd)(PBPM)(CFCO)] complex that was comparable to that of PBPM. Moreover, the trans-to-cis photoisomerization rates of complexes [Ln(tfd)(PBPM)(CFCO)] (La, Eu, Gd) (10-10 s ) were also at the same level as that of PBPM and much higher than azobenzene itself (10-10 s). With the aid of TD-DFT calculations, the luminescence of Eu(III) complexes was found to originate from the attenuation effect of β-diketonates. These features provide the foundation for the development of azobenzene-derived β-diketonates lanthanide(III) complexes with photoisomerization and photoluminescence dual functions.
对通过偶氮苯功能化的配体的配位能力进行了调控，合成了两种新型螯合配体，即(E)-4-(苯基二氮烯基)-N,N-双(吡啶-2-基甲基)苯甲酰肼(CHNO，PBPM)和(E)-4-((4-(二甲基氨基)苯基)二氮烯基)-N,N-双(吡啶-2-基甲基)苯甲酰肼(CHNO，dmPBPM)。这些配体可以提供四个配位原子(一个氧原子和三个氮原子)作为四齿配体，与两个β-二酮(4,4,4-三氟-1-苯基丁烷-1,3-二酮，tfd)以及作为配体和抗衡离子的三氟乙酸根阴离子一起，与镧系(III)离子(La、Eu和Gd)形成四元单元，即[Ln(tfd)(PBPM)(CFCO)] (LnCHFNO)和[Ln(tfd)(dmPBPM)(CFCO)] (LnCHFNO)，其中镧系(III)离子与NO供体基团形成九配位。对所有六种配合物进行了结构表征，获得了四个晶体并通过单晶X射线衍射进一步分析。它们都在单斜P2/c空间群中结晶，具有非常相似的晶格参数，形成一个单帽扭曲方形反棱柱。我们成功地在溶液和固态中观察到了Eu(III)配合物在614 nm波长处的光致发光性质，以及[Eu(tfd)(PBPM)(CFCO)]配合物的反式到顺式光异构化，其量子产率(Φ = 10)与PBPM相当。此外，配合物[Ln(tfd)(PBPM)(CFCO)] (La、Eu、Gd)的反式到顺式光异构化速率(10-10 s)也与PBPM处于同一水平，且远高于偶氮苯本身(10-10 s)。借助TD-DFT计算，发现Eu(III)配合物的发光源于β-二酮的衰减效应。这些特性为开发具有光异构化和光致发光双重功能的偶氮苯衍生β-二酮镧系(III)配合物奠定了基础。
