Tarleton Astrid S, Garcia-Alvarez Jorge C, Wynn Anah, Awbrey Cade M, Roberts Tomas P, Gozem Samer
Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States.
J Phys Chem A. 2022 Jan 27;126(3):435-443. doi: 10.1021/acs.jpca.1c08988. Epub 2022 Jan 11.
Excited-state quantum chemical calculations usually report excitation energies and oscillator strengths, , for each electronic transition. On the other hand, UV-visible spectrophotometric experiments measure energy-dependent molar extinction/attenuation coefficients, ε(), that give absorption band line shapes when plotted. ε() and are related, but this relation is complicated by broadening and solvation effects. We fitted and integrated 100 experimental UV-visible spectra to obtain 164 values for absorption bands appearing in these spectra. The 100 UV-visible spectra belong to solvated organic molecules ranging in size from 6-34 atoms. We estimated uncertainties in the fitting to indicate confidence level in the reported values. The corresponding computed oscillator strengths () were obtained with time-dependent density functional theory and a polarizable continuum solvent model. By expressing experimental and computed absorption strengths using a common quantity, we directly compared and . Although and are well correlated (linear regression = 0.921), in most cases overestimated (regression slope = 1.34). The agreement between absolute and values was substantially improved by accounting for a solvent refractive index factor, as suggested in some derivations in the literature. The 100 digitized UV-visible spectra are included as plain text files in the Supporting Information to aid in benchmarking computational or machine learning methods that aim to simulate realistic UV-visible absorption spectra.
激发态量子化学计算通常会报告每个电子跃迁的激发能和振子强度 。另一方面，紫外 - 可见分光光度实验测量能量依赖的摩尔消光/衰减系数ε()，将其绘制时可得到吸收带的线形。ε()和 是相关的，但这种关系因展宽和溶剂化效应而变得复杂。我们对100个实验性紫外 - 可见光谱进行拟合和积分，以获得这些光谱中出现的吸收带的164个 值。这100个紫外 - 可见光谱属于大小从6到34个原子不等的溶剂化有机分子。我们估计了拟合中的不确定性，以表明所报告的 值的置信水平。相应的计算振子强度（）是使用含时密度泛函理论和可极化连续介质溶剂模型获得的。通过使用一个共同的量来表示实验和计算的吸收强度，我们直接比较了 和 。尽管 和 具有良好的相关性（线性回归 = 0.921），但在大多数情况下 高估了 （回归斜率 = 1.34）。正如文献中的一些推导所建议的，通过考虑溶剂折射率因子，绝对 和 值之间的一致性得到了显著改善。100个数字化的紫外 - 可见光谱作为纯文本文件包含在支持信息中，以帮助对旨在模拟实际紫外 - 可见吸收光谱的计算或机器学习方法进行基准测试。
