Department of Chemistry, University of South Florida, 4202 E. Fowler Ave., CHE205 Tampa, Florida 33620-5250, USA.
J Chem Phys. 2012 Jan 21;136(3):034705. doi: 10.1063/1.3668138.
A high fidelity molecular model is developed for a metal-organic framework (MOF) with narrow (approximately 7.3 Å) nearly square channels. MOF potential models, both with and neglecting explicit polarization, are constructed. Atomic partial point charges for simulation are derived from both fragment-based and fully periodic electronic structure calculations. The molecular models are designed to accurately predict and retrodict material gas sorption properties while assessing the role of induction for molecular packing in highly restricted spaces. Thus, the MOF is assayed via grand canonical Monte Carlo (GCMC) for its potential in hydrogen storage. The confining channels are found to typically accommodate between two to three hydrogen molecules in close proximity to the MOF framework at or near saturation pressures. Further, the net attractive potential energy interactions are dominated by van der Waals interactions in the highly polar MOF - induction changes the structure of the sorbed hydrogen but not the MOF storage capacity. Thus, narrow channels, while providing reasonably promising isosteric heat values, are not the best choice of topology for gas sorption applications from both a molecular and gravimetric perspective.
开发了一种具有狭窄（约 7.3Å）近似正方形通道的金属有机骨架（MOF）的高保真分子模型。构建了具有和不忽略显式极化的 MOF 势能模型。模拟用的原子部分点电荷是从基于片段和全周期性电子结构计算中推导出来的。分子模型旨在通过巨正则蒙特卡罗（GCMC）准确预测和反演材料气体吸附性质，同时评估在高度受限空间中分子堆积的感应作用。因此，通过 GCMC 对 MOF 进行了储氢潜力评估。在接近饱和压力时，发现限制通道通常可容纳两到三个靠近 MOF 骨架的近距离氢气分子。此外，净吸引势能相互作用主要由高度极性 MOF 中的范德华相互作用主导-感应改变了吸附氢的结构，但不改变 MOF 的存储容量。因此，从分子和重量的角度来看，尽管狭窄的通道提供了相当有前途的等焓值，但对于气体吸附应用来说并不是拓扑结构的最佳选择。
