A theoretical comparison of the photophysical and photochemical properties has been made among a series of diarylethene-containing Pt(II) complexes that have two kinds of isomers exhibiting different optical behaviors. It is found that the extension of conjugated systems and electron-withdrawing substituents on a host-ligand promotes the rigidity of structures, which is beneficial to electron transfer during excitation. Moreover, the phosphorescence emission and quenching of complexes can be controlled by utilizing the contrasting optical performance of their two isomers. In closed-ring forms, the complexes suffer phosphorescence quenching due to the inefficient involvement of Pt in the excitation and the low energy gap between the first triplet excited state and the ground state. In open-ring forms, the shift of conjugated systems makes the excitation switch from diarylethene to Pt so that the spin–orbit coupling effect can be achieved, which leads to an effective phosphorescence emission. In addition, the calculation of the radiative decay rate constant k_r is proposed to give an evaluation of the radiative decay process of open-ring forms. And the analysis of the potential energy surface of the triplet-excited state presents an in-depth description of the role of isomerization in its non-radiative decay process. All the above results show the tunability and applicability of diarylethene in organometallic materials. Based on these results, new complexes have been designed as promising candidates with better photoresponsive and phosphorescence performance.

中文翻译：

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一系列含二芳基乙烯的铂配合物的磷光性质：配体光异构化的影响

在一系列含二芳基乙烯的Pt（II）中进行了光物理和光化学性质的理论比较）具有两种异构体的复合物表现出不同的光学行为。发现共轭体系和主体配体上吸电子取代基的延伸促进了结构的刚性，这有利于激发过程中的电子转移。而且，可以通过利用它们的两种异构体的对比光学性能来控制复合物的磷光发射和猝灭。在闭环形式中，由于Pt在激发中的无效参与以及第一三重态激发态与基态之间的低能隙，络合物遭受磷光猝灭。在开环形式下，共轭体系的转变使激发从二芳基乙烯转换为Pt，从而可以实现自旋-轨道耦合效应，导致有效的磷光发射。另外，辐射衰减率常数的计算建议使用k _r评估开环形式的辐射衰减过程。对三重态激发态的势能面的分析对异构化在其非辐射衰变过程中的作用进行了深入的描述。以上所有结果表明二芳基乙烯在有机金属材料中的可调性和适用性。基于这些结果，已将新的配合物设计为具有更好的光响应和磷光性能的有前途的候选物。