Departamento de Química Física y Química Inorgánica, Facultad de Ciencias, IU CINQUIMA, Universidad de Valladolid, 47011 Valladolid, Spain.
Molecules. 2022 Dec 24;28(1):159. doi: 10.3390/molecules28010159.
The rotational spectrum of laser-ablated gallic acid has been recorded using CP-FTMW spectroscopy. Two rotamers have been detected, and their rotational spectra have been assigned and analyzed to obtain the molecular spectroscopic parameters. The observed rotamers have been unambiguously identified in the light of theoretical computations, based on the comparison of the experimental line intensities and rotational parameters with the rotational constants and electric dipole moments predicted from theoretical calculations. The values of the planar inertial moments confirm that the observed conformers are planar, and their relative stability and population have been determined from relative intensity measurements. The B3LYP-D3/6-311++G(2d,p) level has been shown to be the best method among a series of levels normally used to predict the rotational parameters in rotational spectroscopy. In the observed conformers, the three adjacent OH groups are arranged in a sequential form, and the only difference between them lies in the orientation of the COOH group. Although weak attractive OH···O interactions seem to exist, the analysis of the electron density topology does not show the existence of any critical point corresponding to these interactions.
采用 CP-FTMW 光谱法记录了激光烧蚀没食子酸的转动光谱。检测到两种旋转异构体，并对其转动光谱进行了归属和分析，以获得分子光谱参数。根据实验谱线强度和转动参数与理论计算预测的转动常数和电偶极矩的比较，在理论计算的基础上，明确鉴定了观察到的旋转异构体。观察到的构象的平面惯性矩值证实其为平面，并且通过相对强度测量确定了它们的相对稳定性和丰度。B3LYP-D3/6-311++G(2d,p) 水平被证明是在通常用于预测转动光谱中转动参数的一系列水平中最好的方法。在观察到的构象中，三个相邻的 OH 基团呈连续排列形式，它们之间的唯一区别在于 COOH 基团的取向。尽管似乎存在微弱的吸引 OH···O 相互作用，但电子密度拓扑分析并未显示存在与这些相互作用对应的任何临界点。
