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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Structure and Energetics of Ground-State Hypericin: Comparison of Experiment and Theory
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Structure and Energetics of Ground-State Hypericin: Comparison of Experiment and Theory

机译：基态金丝桃素的结构和能量学：实验与理论的比较

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Calculations of the energies of the ground-state un-ionized tautomers of hypericin have been performed at the RMP2/6-31G(d) level of theory, using geometries obtained with the 3-21G basis set and Hartree-Fock wave functions. It is found that only the so-called normal form is likely to be populated at room temperature and that only two of the three possible double tautomers correspond to minima on the potential energy surface. THe effect of continuum aqueous solvation on the tautomer energies is negligible. The O…O distances between which the proton is transferred are reported and are consistent with that required for an adiabatic proton transfer, i.e., ～2.5 A. All 156 vibrational frequencies are tabulated and may be viewed at www.msg.ameslab.gov. For example, the vibrations in the range 320-660 cm~(-1) are coupled with O…O vibrations. The vibrations that are most clearly O…O vibrations occur in the range 400-500 cm~(-1). Twisting of the backbone occurs in a wide range of frequencies, from 230 to 1150 cm~(-1) , while the motion corresponding to an inversion of the (nonplanar) backbone occur at very low frequencies, 80-150 cm~(-1). The results of these calculations are discussed in terms of ground-state heterogeneity of hypericin that has been invoked to explain its spectra and excited-state kinetics.
机译：金丝桃素基态的非离子化互变异构体的能量计算是在理论RMP2 / 6-31G（d）级别上进行的，使用的是使用3-21G基集和Hartree-Fock波函数获得的几何形状。发现在室温下可能仅填充所谓的正常形式，并且三个可能的双互变异构体中仅两个对应于势能表面上的最小值。连续水性溶剂化对互变异构体能量的影响可忽略不计。报告了质子转移之间的O…O距离，并且与绝热质子转移所需的距离一致，即〜2.5A。所有156个振动频率均已制成表格，可在www.msg.ameslab.gov上查看。例如，在320-660 cm〜（-1）范围内的振动与O…O振动耦合。最明显的O…O振动发生在400-500 cm〜（-1）范围内。骨干的扭曲发生在从230到1150 cm〜（-1）的很宽的频率范围内，而与（非平面）骨干倒置相对应的运动发生在非常低​​的频率80-150 cm〜（-1）上）。根据金丝桃素的基态异质性讨论了这些计算的结果，金丝桃素被用来解释其光谱和激发态动力学。

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