Electronic Interaction between Aromatic Chromophores in Dibenzo-Crown Ether Complexes with Alkali Metal Ions Investigated via Cold Gas-Phase Spectroscopy
Electronic Interaction between Aromatic Chromophores in Dibenzo-Crown Ether Complexes with Alkali Metal Ions Investigated via Cold Gas-Phase Spectroscopy
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通过冷气相光谱研究二苯并冠醚配合物中芳香族发色团与碱金属离子之间的电子相互作用
DOI：
10.1021/acs.jpca.3c01447
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Inokuchi Yoshiya
中科院分区：
文献类型：
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作者：
Kida Motoki;Ujihira Tomoyuki;Kubo Mayuko;Muramatsu Satoru;Ebata Takayuki;Inokuchi Yoshiya
本文研究了二苯并-21-冠-7 （DB21C7）和二苯并-24-冠-8 （DB24C8）与碱金属离子配合物的几何结构和电子结构，分别鉴定为M+(DB21C7)和M+(DB24C8) （M = Na， K， Rb和Cs）。我们观察了这些配合物在冷（~ 10 K）气相条件下的紫外光解（UVPD）光谱。M+(DB21C7)和M+(DB24C8)配合物的构象通过UVPD光谱与计算得到的局部最小电子跃迁进行了比较。研究了M+(DB21C7)和M+(DB24C8)配合物中两个苯发色团的电子激发态之间的相互作用，并与先前研究的配合物（二苯并-15-冠-5 （DB15C5）和二苯并-18-冠-6 (DB18C6)）进行了比较。M+(DB21C7)配合物的s1 - s0和s2 - s0电子激发几乎局限在一个苯环上。相比之下，M+(DB24C8) （M = K， Rb和Cs）配合物的封闭构象在两个发色团上因电子激发而离域，苯环之间表现出强烈的电子相互作用。对于M+(DB24C8)配合物（M = K， Rb和Cs），苯环之间的短距离（~ 3.9 Å）导致苯发色团之间的强相互作用。我们得出结论，M+(DB24C8)配合物中的这种强相互作用与UVPD光谱中的宽吸收密切相关，表明K+(DB24C8), Rb+(DB24C8)和Cs+(DB24C8)配合物存在分子内准分子。
This study investigated the geometric and electronic structures of dibenzo-21-crown-7 (DB21C7) and dibenzo-24-crown-8 (DB24C8) complexes with alkali metal ions, identified as M+(DB21C7) and M+(DB24C8) (M = Na, K, Rb, and Cs), respectively. We observed the ultraviolet photodissociation (UVPD) spectra of these complexes under cold (∼10 K) gas-phase conditions. The conformations of the M+(DB21C7) and M+(DB24C8) complexes were determined by comparing the UVPD spectra with the calculated electronic transitions of the local-minimum forms. The interactions between the electronic excited states of the two benzene chromophores in the M+(DB21C7) and M+(DB24C8) complexes were examined and compared with those of previously studied complexes (dibenzo-15-crown-5 (DB15C5) and dibenzo-18-crown-6 (DB18C6)). The S1–S0and S2–S0electronic excitations of the M+(DB21C7) complexes were almost localized in one of the benzene rings. In contrast, the closed conformers of the M+(DB24C8) (M = K, Rb, and Cs) complexes were delocalized over the two chromophores for electronic excitations, exhibiting strong electronic interactions between the benzene rings. For the M+(DB24C8) complexes (M = K, Rb, and Cs), the short distance between the benzene rings (∼3.9 Å) led to a strong interaction between the benzene chromophores. We conclude that this strong interaction in the M+(DB24C8) complexes correlates strongly with the broad absorption in the UVPD spectra, suggesting the presence of an intramolecular excimer for the K+(DB24C8), Rb+(DB24C8), and Cs+(DB24C8) complexes.