Nature of the lowest triplet states of 4′-substituted N-phenylphenothiazine derivatives
作者:Paweł Borowicz、Jerzy Herbich、Andrzej Kapturkiewicz、Romana Anulewicz-Ostrowska、Jacek Nowacki、Günter Grampp
DOI:10.1039/b005058j
日期:——
The
nature of the lowest triplet state of the donorâacceptor N-phenylphenothiazine derivatives has been studied
by means of phosphorescence and EPR spectroscopy in various low temperature glasses. The triplet excitation
of N-phenylphenothiazine and N-(p-anisyl)-phenothiazine is localised within the phenothiazine subunit.
On the contrary, the 77 K phosphorescence of the molecules containing an electron acceptor group (i.e. âCN, âCOCH3 or âCOC6H5 at the 4â² position) is similar to that for benzonitrile, acetophenone or benzophenone, respectively, although the energy levels of their T1 states are higher than that of phenothiazine. With increasing temperature, however, their phosphorescence becomes similar to that characteristic for phenothiazine.
This finding has been explained in terms of the excited-state intramolecular energy transfer accompanied by the planarisation of the phenothiazine kernel. The
results of crystallographic investigations support this hypothesis.
我们在各种低温玻璃中通过磷光和 EPR 光谱研究了供体受体 N-苯基吩噻嗪衍生物最低三重态的性质。N-苯基吩噻嗪和 N-(对甲氧基)-吩噻嗪的三重态激发位于吩噻嗪亚基内。 相反,含有电子受体基团的分子(即:âCN、âCO、âN-(对甲氧基)-吩噻嗪)的 77 K 磷光激发位于吩噻嗪亚基内。相反,含有电子受体基团(即 4â²位上的âCN、âCOCH3 或âCOC6H5)的分子的 77 K 磷光分别与苯甲腈、苯乙酮或二苯甲酮相似,尽管它们的 T1 态能级高于吩噻嗪。对这一发现的解释是,激发态分子内能量转移伴随着吩噻嗪核的平面化。晶体学研究结果支持这一假设。