Photophysical properties of carbazole–terephthalate cyclophane (Cz–TP) were studied. The absorption spectra of Cz–TP in various solvents were slightly broadened due to the distortion of the carbazole (Cz) moiety and became similar to that of a reference compound of carbazole–benzene cyclophane (Cz–Bz). The absorption spectrum and the peak wavelengths of Cz–TP were insensitive to the solvent polarity. These findings show that there is transannular π–π electronic interaction between the Cz and TP moieties but that the charge transfer interaction from the Cz to TP moieties is small in the ground state. On the other hand, the emission spectrum was broad, structureless, and red-shifted compared with that of the reference compound. The peak wavelength of the emission was shifted to a longer wavelength with increases in the dielectric constant of solvents. The peak shift was quantitatively explained by the Lippert–Mataga formula. Therefore, we conclude that the broad emission is due to the intramolecular exciplex in Cz–TP. The dielectric constant of 2-methyl tetrahydrofuran was evaluated from the exciplex emission of Cz–TP ranging from 77 to 292 K, indicating that the Cz–TP molecule is an excellent polarity probe not only in a liquid phase but also in a solid phase over a wide temperature range.
研究了
咔唑-
对苯二甲酸酯环芳烷(Cz-TP)的光物理性质。由于
咔唑 (Cz) 部分的变形,Cz-TP 在各种溶剂中的吸收光谱略有展宽,并且与
咔唑-苯环芳 (Cz-Bz) 参考化合物的吸收光谱相似。 Cz-TP 的吸收光谱和峰值波长对溶剂极性不敏感。这些发现表明,Cz 和 TP 部分之间存在跨环 π-π 电子相互作用,但基态下从 Cz 到 TP 部分的电荷转移相互作用很小。另一方面,与参考化合物相比,发射光谱较宽、无结构且红移。随着溶剂介电常数的增加,发射的峰值波长移动到更长的波长。峰移由 Lippert-Mataga 公式定量解释。因此,我们得出结论,宽发射是由于 Cz-TP 中的分子内激基复合物造成的。通过 Cz-TP 在 77 至 292 K 范围内的激基复合物发射评估了
2-甲基四氢呋喃的介电常数,表明 Cz-TP 分子不仅在液相中而且在固相中都是优异的极性探针。温度范围宽。