Faculty of Chemistry, University of Wrocław, ul. F. Joliot-Curie 14, 50-383 Wrocław, Poland.
J Chem Inf Model. 2015 Jun 22;55(6):1148-57. doi: 10.1021/ci500560g. Epub 2015 May 19.
1,8-Bis(dimethylamino)-4,5-dihydroxynaphthalene has been investigated on the basis of static DFT computations and Car-Parrinello molecular dynamics. The simulations were performed in the gas phase and in the solid state. The studied "zwitterionic proton sponge" possesses two, short intramolecular hydrogen bonds (O-H···O and N-H···N) classified as Low Barrier Hydrogen Bonds (LBHBs); therefore, the system studied is strongly anharmonic. In addition, the compound exists as a "zwitterion" in solution and in the solid state, thus the intramolecular hydrogen bonds belong to the class of charge-assisted interactions. The applied quantum-chemical methods enabled investigations of metric and spectroscopic parameters of the molecule. The time-evolution investigations of the H-bonding showed a strong delocalization of the bridge protons and their high mobility, reflected in the low barriers on the free energy surfaces. Frequent proton transfer phenomena were noticed. The power spectra of atomic velocity were computed to analyze the vibrational features associated with O-H and N-H stretching. A broad absorption was indicated for both hydrogen bridges. For the first time, Car-Parrinello molecular dynamics results are reported for the compound, and they indicate a broad, shallow but not barrierless, potential well for each of the bridge protons.
1,8-双（二甲氨基）-4,5-二羟基萘已基于静态 DFT 计算和 Car-Parrinello 分子动力学进行了研究。模拟在气相和固态下进行。所研究的“两性离子质子海绵”具有两个短的分子内氢键（O-H···O 和 N-H···N），被归类为低能垒氢键（LBHBs）；因此，所研究的系统是强烈非谐的。此外，该化合物在溶液中和固态中都以“两性离子”形式存在，因此分子内氢键属于电荷辅助相互作用的类别。所应用的量子化学方法能够研究分子的度量和光谱参数。氢键的时间演化研究表明，桥接质子具有很强的离域性和高迁移率，这反映在自由能曲面上的低能垒上。频繁的质子转移现象被注意到。计算了原子速度的功率谱，以分析与 O-H 和 N-H 伸缩相关的振动特征。两个氢键都显示出宽的吸收。首次报道了该化合物的 Car-Parrinello 分子动力学结果，它们表明每个桥接质子都有一个宽而浅但无势垒的势阱。
