Center for Optical and Laser Materials Research, St. Petersburg State University, Ulianovskaya 5, 198504 St. Petersburg, Russia.
Federal Scientific Agro-Engineering Center VIM, 1st Institutskiy proezd 5, 109428 Moscow, Russia.
Spectrochim Acta A Mol Biomol Spectrosc. 2023 May 15;293:122469. doi: 10.1016/j.saa.2023.122469. Epub 2023 Feb 9.
The structure of the rubrofusarin molecule (CAS: 3567-00-8, IUPAC name 5,6-dihydroxy-8-methoxy-2-methyl-4H-benzo[g]chromen-4-one, molecular formula CHO) and its possible rotational conformers and tautomer were investigated within DFT approach. It was noted that for a stable molecules the group symmetry is close to Cs. The smallest potential barrier for rotational conformers is associated with the methoxy group rotation. The rotation of hydroxyl groups leads to a stable states that are substantially higher in energy than the ground state. Modeling and interpretation of vibrational spectra for the case of the ground state molecule in the gas phase and methanol solution was carried out, the influence of the solvent is discussed. The modelling of electronic singlet transition within the TD-DFT approach and the interpretation of obtained UV-vis absorbance spectra were carried out. A relatively small shift in the two most active absorption bands wavelength takes place for methoxy group rotation conformer. At the same time the redshift of the HOMO-LUMO transition takes place for this conformer. Much larger long wavelength shift of the absorption bands was noted for the tautomer.
红曲菌素分子（CAS：3567-00-8，IUPAC 名称 5,6-二羟基-8-甲氧基-2-甲基-4H-苯并[g]色烯-4-酮，分子式 CHO）及其可能的旋转构象异构体和互变异构体在 DFT 方法中进行了研究。值得注意的是，对于稳定的分子，基团对称性接近 Cs。旋转构象异构体的最小势能垒与甲氧基的旋转有关。羟基的旋转导致稳定状态的能量明显高于基态。对气相和甲醇溶液中基态分子的振动光谱进行了建模和解释，讨论了溶剂的影响。在 TD-DFT 方法中进行了单重态电子跃迁的建模，并对获得的紫外-可见吸收光谱进行了解释。甲氧基旋转构象异构体的两个最活跃的吸收带波长发生了相对较小的位移。同时，这个构象异构体的 HOMO-LUMO 跃迁发生了红移。互变异构体的吸收带发生了更大的长波长位移。
