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一个可合成调节的系统来控制MLCT激发状态寿命和铁中的旋转状态

Steven M Fatur¹, Samuel G Shepard¹, Robert F Higgins²

¹Department of Chemistry and Biochemistry, University of Colorado Boulder , Boulder, Colorado 80309, United States.

Journal of the American Chemical Society

|March 2, 2017

概括

用化特皮里丁连接体修改的铁复合物显示可调节的自旋状态和激发状态寿命. 这些自旋交叉材料的硬性应变延长了电荷传输寿命,有助于先进应用的分子设计.

科学领域:

协调化学
材料科学
光物理学

背景情况:

在旋转交叉 (SCO) 研究中,双同质Fe(II) 复合物与2,2':6',2′′-特皮里迪尔 (tpy) 配体至关重要.
调节连接物替代剂影响这些铁复合物的电子和结构性质,影响它们的磁性行为.
了解激发状态的动态是开发光敏材料的关键.

研究的目的:

用 (dftpy), (dctpy) 和 (dbtpy) 替代的胺连接物合成和表征一系列Fe(II) 复合物.
通过使用可变波长激光激发来研究这些复合物的旋转交叉行为和激发状态动力学.
要将结构修改,特别是硬质应变与金属到合物转移 (MLCT) 寿命的变化相关联.

主要方法:

用dftpy,dctpy和dbtpy连接物合成双同质Fe (II) 复合物.
包括可变温度磁感应度测量的光谱表征,以确定旋转状态.
超快速激光谱 (530nm和400nm激发) 探测激发状态动态并测量MLCT寿命.

主要成果:

[Fe(dctpy) ₂]²⁺和[Fe(dbtpy) ₂²⁺由于联体诱导的应变而表现出高旋转五重奏基态.
[Fe(dftpy) ₂]²⁺显示了220K的T_1/2的旋转交叉,在室温下显示单元和五元状态的混合.
在400nm激发导致显著增加的MLCT寿命,从14.0ps为[Fe(dftpy) ₂]²⁺到17.4ps为[Fe(dbtpy) ₂.

结论:

在Fe (II) 基复合物中的基菌株可以有效地减缓非辐射衰变路径,延长MLCT寿命.
观察到的趋势支持采用互联体相互作用来控制形态动态和状态能量的设计策略.
这些发现为设计具有适合分子电子和传感的光物理性质的新型旋转交叉材料提供了途径.

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