Akai Nobuyuki, Harada Takanori, Shin-Ya Kei, Ohno Keiichi, Aida Misako
Center for Quantum Life Sciences, Hiroshima University, 1-3-1, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan.
J Phys Chem A. 2006 May 11;110(18):6016-22. doi: 10.1021/jp056290t.
The photoreaction of 2-amino-5-methylpyridine was investigated by matrix-isolation infrared spectroscopy and DFT calculation. Photoinduced reversible amino (N=C-NH(2))-imino (NH-C=NH) tautomerism was found between 2-amino-5-methylpyridine and 5-methyl-2(1H)-pyridinimine; the amino tautomer changes to the imino tautomer by UV irradiation (340>lambda>or= 300 nm) and the reverse change occurs by longer-wavelength light irradiation (420>lambda>or= 340 nm). The results of the CASSCF calculation revealed that the amino-imino tautomerism proceeds in vibrational relaxation process from electronic excited state to the ground state. The IR spectra of 2-amino-5-methylpyridine in the T(1) state and 5-methyl-2-pyridinamino radical were also obtained by UV irradiation (lambda>or= 300 nm).
通过基质隔离红外光谱和密度泛函理论计算研究了2-氨基-5-甲基吡啶的光反应。发现2-氨基-5-甲基吡啶与5-甲基-2(1H)-吡啶亚胺之间存在光诱导的可逆氨基（N=C-NH₂）-亚氨基（NH-C=NH）互变异构；氨基互变异构体通过紫外线照射（340＞λ≥300nm）转变为亚氨基互变异构体，而通过波长更长的光照射（420＞λ≥340nm）则发生逆向变化。CASSCF计算结果表明，氨基-亚氨基互变异构在从电子激发态到基态的振动弛豫过程中进行。通过紫外线照射（λ≥300nm）还获得了处于T(1)态的2-氨基-5-甲基吡啶和5-甲基-2-吡啶氨基自由基的红外光谱。
