Effects of Ligand Substitution on the Optical and Electrochemical Properties of (Pyridinedipyrrolide)zirconium Photosensitizers
Effects of Ligand Substitution on the Optical and Electrochemical Properties of (Pyridinedipyrrolide)zirconium Photosensitizers
复制标题
配体取代对(吡啶二吡咯)锆光敏剂光学和电化学性质的影响
DOI：
10.1021/acs.inorgchem.0c02343
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发表时间：
2020
影响因子：
4.6
通讯作者：
Milsmann, Carsten
中科院分区：
文献类型：
--
作者：
Zhang, Yu;Leary, Dylan C.;Belldina, Anne M.;Petersen, Jeffrey L.;Milsmann, Carsten
合成了7个双（吡啶二吡咯）锆配合物Zr（R1 PDPR 2）2，其中[R1 PDPR 2]2-为[2，6-双（5-R1-3-R2- 1H-吡咯-2-基）吡啶]的双去质子化形式，并通过NMR、UV/维斯吸收光谱、发射光谱和循环伏安法进行了表征。通过单晶X射线晶体学确定分子结构。在苯溶液中，所有配合物在可见光激发下均表现出很长的发光寿命（τ = 190-576 μs）和很高的量子效率（ΦPL= 0.10-0.38）。吡咯环上的取代基对这些化合物的光致发光和电化学性质有显著的影响。的R2取代基（R2= H，Me，Ph，或C6 F5）的复合物的吸收和发射曲线上只显示有限的影响，但允许系统的地面和激发态的氧化还原电位在几乎600 mV的范围内调谐。R1取代基（R1= H，Me，Ph，或2，4，6-Me 3 Ph）通过电子效应影响光学和电化学性质。此外，R1取代基对化合物的结构灵活性和整体稳定性具有深远的影响。Zr（PDP）2核心从理想化的D2 d对称性在固体状态下的扭曲可以追溯到R1取代基的空间分布，并与所观察到的斯托克斯位移为每个化合物。具有最小配体系统Zr（HPDPH）2的络合物在四氢呋喃（THF）溶液中配位两个额外的溶剂分子，这允许光致发光的八配位Zr（HPDPH）2（THF）2的分离。使用最还原的衍生物Zr（MePDPMe）2的芳基碘和芳基氯的光氧化还原催化脱卤突出了Zr（PDP）2光敏剂在温和条件下用绿色光激发时促进具有挑战性的还原转化的潜力。
A series of seven bis(pyridinedipyrrolide)zirconium complexes, Zr(R1PDPR2)2, where [R1PDPR2]2–is the doubly deprotonated form of [2,6-bis(5-R1-3-R2-1H-pyrrol-2-yl)pyridine], were prepared and characterized in solution by NMR, UV/vis absorption, and emission spectroscopy and cyclic voltammetry. The molecular structures were determined by single-crystal X-ray crystallography. All complexes exhibit remarkably long emission lifetimes (τ = 190–576 μs) with high quantum efficiencies (ΦPL= 0.10–0.38) upon excitation with visible light in a benzene solution. The substituents on the pyrrolide rings were shown to have significant effects on the photoluminescence and electrochemical properties of these compounds. The R2substituents (R2= H, Me, Ph, or C6F5) show only limited effects on the absorption and emission profiles of the complexes but allow systematic tuning of the ground- and excited-state redox potentials over a range of almost 600 mV. The R1substituents (R1= H, Me, Ph, or 2,4,6-Me3Ph) influence both the optical and electrochemical properties through electronic effects. Additionally, the R1substituents have profound consequences for the structural flexibility and overall stability of the compounds. Distortions of the Zr(PDP)2core from idealizedD2dsymmetry in the solid state can be traced to the steric profiles of the R1substituents and correlate with the observed Stokes shifts for each compound. The complex with the smallest ligand system, Zr(HPDPH)2, coordinates two additional solvent molecules in a tetrahydrofuran (THF) solution, which allowed the isolation of photoluminescent, eight-coordinate Zr(HPDPH)2(THF)2. The photoredox catalytic dehalogenation of aryl iodides and aryl chlorides using the most reducing derivative, Zr(MePDPMe)2, highlights the potential of Zr(PDP)2photosensitizers to promote challenging reductive transformations under mild conditions upon excitation with green light.