Woodhouse Joanne L, Henley Alice, Parkes Michael A, Fielding Helen H
Department of Chemistry , University College London , 20 Gordon Street , London WC1H 0AH , U.K.
J Phys Chem A. 2019 Apr 4;123(13):2709-2718. doi: 10.1021/acs.jpca.8b11121. Epub 2019 Mar 18.
Phenolates and their substituted analogues are important molecular motifs in many biological molecules, including the family of fluorescent proteins based on green fluorescent protein. We have used a combination of anion photoelectron velocity-map imaging measurements and quantum chemistry calculations to probe the electronic structure of the phenolate anion and difluoro- and dimethoxy-substituted analogues. We report vertical detachment energies (VDEs) and quantify the photoelectron angular distributions. The VDEs for phenolate (2.26 ± 0.03 eV, 3.22 ± 0.02 eV) are in agreement with high-resolution measurements, whereas the values for the substituted analogues (2.61 ± 0.03 eV for difluorophenolate; ∼2.35 eV for dimethoxyphenolate) are new measurements. We also report adiabatic excitation energies (AEEs) of anion resonances and discuss their contributions to the overall photoelectron angular distributions. The AEE of the lowest lying resonance in phenolate (∼3.36 eV) is consistent with previous measurements, whereas the value for the next resonance (∼3.7 eV) is a new measurement. The AEEs of the resonances in the substituted analogues (∼3.74 eV for difluorophenolate; ∼3.4 and 3.74 eV for dimethoxyphenolate) are new measurements.
酚盐及其取代类似物是许多生物分子中的重要分子基序，包括基于绿色荧光蛋白的荧光蛋白家族。我们结合了阴离子光电子速度映射成像测量和量子化学计算来探究酚盐阴离子以及二氟和二甲氧基取代类似物的电子结构。我们报告了垂直脱附能（VDEs）并对光电子角分布进行了量化。酚盐的VDEs（2.26±0.03 eV，3.22±0.02 eV）与高分辨率测量结果一致，而取代类似物的值（二氟酚盐为2.61±0.03 eV；二甲氧基酚盐约为2.35 eV）是新的测量结果。我们还报告了阴离子共振的绝热激发能（AEEs），并讨论了它们对整体光电子角分布的贡献。酚盐中最低能级共振的AEE（约3.36 eV）与先前的测量结果一致，而接下来共振的值（约3.7 eV）是新的测量结果。取代类似物中共振的AEEs（二氟酚盐约为3.74 eV；二甲氧基酚盐为约3.4和3.74 eV）是新的测量结果。
