Abstract
Solvent shift effect on absorption spectra of oxodipyrromethenes and bilirubin IX-${\alpha}$ were studied. In methanol or acetic acid the oxodipyrromethenes exist as flat conjugated conformations and in strong acid medium as enol forms of oxodipyrromethenes and bilirubin. The visible absorption bands of bilirubin IX-${\alpha}$ and the model compounds, oxodipyrrinethenes, are assigned as ${\pi}{\rightarrow}{\pi}^{\ast}$transition due to their large molar absorption coefficients and to the fact that the more alkyl-substituted one absorbs at rather longer wavelengths than less alkyl-substituted one. A weak blue shift of bilirubin IX-${\alpha}$ in polar solvent is probably attribute to disruption of intramolecular hydrogen bond.
몇 가지 용매에 대하여 옥소디피로메텐과 빌리루빈의 흡수스펙트라 이동현상을 연구하였다. 메탄올이나 아세트산용액 중에서는 옥소디피로메텐이 수소결합을 하여 컨쥬게이션이 많이 되는 형으로 존재하며, 강산 존재하에서는 엔올 형으로 흡수한다. 옥소디피로메텐이나 빌리루빈의 큰 몰흡광계수와 많은 알킬기가 치환된 옥소디피로메텐이 장파장을 흡수하는 것으로 보아 이들의 처음여기 상태는 ${\pi}{\rightarrow}{\pi}^{\ast}$전이일 것이다.