Unraveling the Electronic Structure of Azolehemiporphyrazines: Direct Spectroscopic Observation of Magnetic Dipole Allowed Nature of the Lowest 蟺鈥撓€* Transition of 20蟺-Electron Porphyrinoids

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• 作者：Atsuya Muranaka ; Shino Ohira ; Naoyuki Toriumi ; Machiko Hirayama ; Fumiko Kyotani ; Yukie Mori ; Daisuke Hashizume ; Masanobu Uchiyama
• 刊名：Journal of Physical Chemistry A
• 出版年：2014
• 出版时间：June 26, 2014
• 年：2014
• 卷：118
• 期：25
• 页码：4415-4424
• 全文大小：566K
• ISSN：1520-5215

文摘

Hemiporphyrazines are a large family of phthalocyanine analogues in which two isoindoline units are replaced by other rings. Here we report unambiguous identification of 20蟺-electron structure of triazolehemiporphyrazines (1, 2) and thiazolehemiporphyrazine (3) by means of X-ray analysis, various spectroscopic methods, and density functional theory (DFT) calculations. The hemiporphyrazines were compared in detail with dibenzotetraazaporphyrin (4), a structurally related 18蟺-electron molecule. X-ray analysis revealed that tetrakis(2,6-dimethylphenyloxy)triazolehemiporphyrazine (1b) adopted planar geometry in the solid state. A weak absorption band with a pronounced vibronic progression, observed for all the hemiporphyrazines, was attributed to the lowest 蟺鈥撓€* transition with the electric-dipole-forbidden nature. In the case of intrinsically chiral vanadyl triazolehemiporphyrazine (2), a large dissymmetry (g) factor was detected for the CD signal corresponding to the lowest 蟺鈥撓€* transition with the magnetic-dipole-allowed nature. Molecular orbital analysis and NICS calculations showed that the azolehemiporphyrazines have a 20蟺-electron system with a weak paratropic ring current.