The SFI Strategic Research Cluster in Solar Energy Conversion, School of Chemical and Bioprocess Engineering, University College Dublin, Belfield, Dublin 4, Ireland.
Inorg Chem. 2012 May 7;51(9):5282-8. doi: 10.1021/ic300224w. Epub 2012 Apr 11.
Using density functional theory (DFT) methods, we have investigated two possible mechanisms for atmospheric CO(2) fixation in the cavity of the dinuclear zinc(II) octa-azacryptate, and the subsequent reaction with methanol whereby this latter reaction transforms the (essentially) chemically inert CO(2) into useful products. The first mechanism (I) was proposed by Chen et al. [Chem.-Asian J. 2007, 2, 710], and involves the attachment of one CO(2) molecule onto the hydroxyl-cryptate form, resulting in the formation of a bicarbonate-cryptate species and subsequent reaction with one methanol molecule. In addition, we suggest another mechanism that is initiated via the attachment of a methanol molecule onto one of the Zn-centers, yielding a methoxy-cryptate species. The product is used to activate a CO(2) molecule and generate a methoxycarbonate-cryptate. The energy profiles of both mechanisms were determined, and we conclude that, while both mechanisms are energetically feasible, free energy profiles suggest that the scheme proposed by Chen et al. is most likely.
我们运用密度泛函理论（DFT）方法，研究了双核锌（II）八元氮杂穴醚在大气 CO2 固定腔中的两种可能机制，以及随后与甲醇的反应，后者将（本质上）化学惰性的 CO2 转化为有用的产物。第一种机制（I）由 Chen 等人提出[Chem.-Asian J. 2007, 2, 710]，涉及一个 CO2 分子附着在羟基穴醚形式上，导致形成碳酸氢盐穴醚物种，然后与一个甲醇分子反应。此外，我们还提出了另一种机制，该机制是通过甲醇分子附着在一个 Zn 中心上开始的，生成甲氧基穴醚物种。该产物用于激活 CO2 分子并生成甲氧基碳酸盐穴醚。我们确定了这两种机制的能量曲线，得出的结论是，尽管这两种机制在能量上都是可行的，但自由能曲线表明，Chen 等人提出的方案最有可能。
