Department of Chemistry, King's College London, Britannia House, 7 Trinity Street, London SE1 1DB, UK.
Université Paris Est Créteil and Université Paris Cité, CNRS, LISA, F-94010 Créteil, France.
Molecules. 2023 Feb 24;28(5):2153. doi: 10.3390/molecules28052153.
The structure and interactions of oxygenated aromatic molecules are of atmospheric interest due to their toxicity and as precursors of aerosols. Here, we present the analysis of 4-methyl-2-nitrophenol (4MNP) using chirped pulse and Fabry-Pérot Fourier transform microwave spectroscopy in combination with quantum chemical calculations. The rotational, centrifugal distortion, and N nuclear quadrupole coupling constants of the lowest-energy conformer of 4MNP were determined as well as the barrier to methyl internal rotation. The latter has a value of 106.4456(8) cm, significantly larger than those from related molecules with only one hydroxyl or nitro substituent in the same para or meta positions, respectively, as 4MNP. Our results serve as a basis to understand the interactions of 4MNP with atmospheric molecules and the influence of the electronic environment on methyl internal rotation barrier heights.
含氧芳香族分子的结构和相互作用因其毒性以及作为气溶胶前体而引起了大气科学界的关注。在这里，我们使用啁啾脉冲和 Fabry-Pérot 傅里叶变换微波光谱学结合量子化学计算，对 4-甲基-2-硝基苯酚（4MNP）进行了分析。确定了 4MNP 最低能量构象的旋转、离心扭曲和 N 核四极矩耦合常数，以及甲基内旋转的势垒。后者的值为 106.4456(8)cm，明显大于具有相同对位或间位的一个羟基或硝基取代基的相关分子的内旋转势垒高度，如 4MNP。我们的结果为理解 4MNP 与大气分子的相互作用以及电子环境对甲基内旋转势垒高度的影响提供了基础。
