Balancing the interplay between ligand ejection and therapeutic window light absorption in ruthenium polypyridyl complexes
Balancing the interplay between ligand ejection and therapeutic window light absorption in ruthenium polypyridyl complexes
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DOI：
10.1039/d2dt01237e
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发表时间：
2022-06-15
影响因子：
4
通讯作者：
Ashford，Dennis L.
中科院分区：
文献类型：
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作者：
McCullough，Annie B.;Chen，Jiaqi;Ashford，Dennis L.
钌多吡啶配合物作为光化学疗法（photochemotherapies，PCT）已经获得了显著的兴趣，其中它们的激发态性质在光细胞毒性机制和功效中起关键作用。本文报道了一系列用于模拟PCTs的[Ru（bpy）2（N-N）]2+（其中bpy = 2，2 ′-联吡啶; N-N是一个双齿多吡啶配体）型钌（II）多吡啶配合物的电化学、光谱化学和电子物理分析。在该系列中，通过增加共轭和/或引入电负性杂原子来修饰N-N配体，以将金属-配体电荷转移（MLCT）吸收转移到PCT的治疗窗口（600-1100 nm）附近，同时引入空间体积以触发光诱导配体解离。最低能量MLCT吸收峰从λmax = 454 nm红移到564 nm，发射能量从λmax = 620 nm降低到850 nm。光诱导配体喷射和温度依赖性发射研究揭示了红移MLCT激发和进入解离3dd* 态之间的重要相互作用，对于测量的复合物，3 MLCT * 和3dd* 态之间的能垒范围为850 cm−1至2580 cm−1。这项工作表明，在未来的配体和配合物的PCT设计的MLCT歧管和3dd* 状态能级的理解的重要性。
Ruthenium polypyridyl complexes have gained significant interest as photochemotherapies (PCTs) where their excited-state properties play a critical role in the photo-cytotoxicity mechanism and efficacy. Herein we report a systematic electrochemical, spectrochemical, and photophysical analysis of a series of ruthenium(II) polypyridyl complexes of the type [Ru(bpy)2(N–N)]2+ (where bpy = 2,2′-bipyridine; N–N is a bidentate polypyridyl ligand) designed to mimic PCTs. In this series, the N–N ligand was modified through increased conjugation and/or incorporation of electronegative heteroatoms to shift the metal-to-ligand charge-transfer (MLCT) absorptions near the therapeutic window for PCTs (600–1100 nm) while incorporating steric bulk to trigger photoinduced ligand dissociation. The lowest energy MLCT absorptions were red-shifted from λmax = 454 nm to 564 nm, with emission energies decreasing from λmax = 620 nm to 850 nm. Photoinduced ligand ejection and temperature-dependent emission studies revealed an important interplay between red-shifting MLCT absorptions and accessing the dissociative 3dd* states, with energy barriers between the 3MLCT* and 3dd* states ranging from 850 cm−1 to 2580 cm−1 for the complexes measured. This work demonstrates the importance of understanding both the MLCT manifold and 3dd* state energy levels in the future design of ligands and complexes for PCT.