Departamento de Física y Química Teórica, Facultad de Química, UNAM, Circuito Escolar, Ciudad Universitaria., México, D.F 04510.
Phys Chem Chem Phys. 2010 May 14;12(18):4783-90. doi: 10.1039/b922203k. Epub 2010 Mar 16.
The electronic structure and hydrogen bonding of the stable isomers of catechol and its complexes with one to three water molecules is studied by means of theoretical methods. A conformational analysis based on a simulated annealing search on the potential energy surface of each complex was carried out previous to the quantum chemical energy minimization. Twenty three stable conformers were found including some involving a pi-interaction between the catechol moiety and a water molecule. The topological properties of the electron density reveal the presence of an intramolecular hydrogen bond only in the case of one complex with three water molecules. The infrared spectra of these molecules were computed and compared to available experimental results. An alternative assignment of the experimental vibrational spectrum within the range 3340-3750 cm(-1) of the catechol-3(H(2)O) complex (M. Gerhards, C. Unterberg, and K. Kleinermanns, Phys. Chem. Chem. Phys. 2000, 2, p. 5538) is proposed. The red-shift observed for the stretching vibrational frequency of the catechol hydrogen donor hydroxyl group in the presence of water molecules is rationalized in terms of the properties of the electron distribution and a Darwinian family tree is proposed to classify the diverse structural and energetic characteristics of the stable complexes found.
通过理论方法研究了儿茶酚及其与一个至三个水分子形成的配合物的稳定异构体的电子结构和氢键。在进行量子化学能量最小化之前，对每个配合物的势能表面进行了基于模拟退火搜索的构象分析。发现了 23 种稳定构象，其中一些涉及儿茶酚部分与水分子之间的π相互作用。电子密度的拓扑性质表明，只有在一个具有三个水分子的配合物中才存在分子内氢键。计算了这些分子的红外光谱，并与可用的实验结果进行了比较。对儿茶酚-3（H2O）配合物（M. Gerhards，C. Unterberg 和 K. Kleinermanns，Phys. Chem. Chem. Phys. 2000，2，p.5538）在 3340-3750cm-1 范围内的实验振动光谱提出了一种替代的归属。在水分子存在的情况下，儿茶酚氢供体羟基的伸缩振动频率发生红移，这可以用电子分布的性质来解释，并提出了一个达尔文树形图来对所发现的稳定配合物的不同结构和能量特征进行分类。
