Alzahrani Khalid A H, Deeth Robert J
Inorganic Computational Chemistry Group, University of Warwick, Coventry, CV4 7AL, UK.
School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, Scotland, EH9 3FJ, UK.
J Mol Model. 2016 Apr;22(4):80. doi: 10.1007/s00894-016-2949-5. Epub 2016 Mar 15.
A new all-atom first-principles force field (FF) is constructed for the bimetallic, four-bladed zinc paddlewheel (ZPW) motif. Zinc-ligand interactions are described via Morse functions and the angular geometry at the metal centers is modeled with a pure ligand-ligand repulsion term. The ZPW-FF is principally based on 15 DFT-optimized model systems of general formula ZnPR.nL, where ZnP is the base Zn2(O2CR)4 unit, R = H, CH3 or CF3, L = NH3 or pyridine, and n = 0, 1 or 2. It correctly generates the distorted tetrahedral coordination of the uncapped [Zn2(O2CR)4] species in their ground states as well as giving reasonable structures and energies for the higher symmetry D4h transition state conformations. The zinc-ligand Morse function reference distance, r 0 , is further refined against 30 complexes located in the Cambridge Structural Database and this FF is applied to pore models of the flexible metal-organic framework (MOF) [Zn(bdc)2(dabco)]n (bdc = 1,4-benzendicarboxylate; dabco = 1,4-diazabicyclo(2.2.2)octane). A single pore model reproduces the unit cell of the evacuated MOF system while a 3×3 grid model is necessary to provide good agreement with the observed pronounced structural changes upon adsorption of either dimethylformamide or benzene.
为双金属四叶锌桨轮（ZPW）基序构建了一种新的全原子第一性原理力场（FF）。锌-配体相互作用通过莫尔斯函数描述，金属中心的角几何结构用纯配体-配体排斥项建模。ZPW-FF主要基于15个通式为ZnPR.nL的DFT优化模型系统，其中ZnP是基础Zn2(O2CR)4单元，R = H、CH3或CF3，L = NH3或吡啶，n = 0、1或2。它能正确生成未封端的[Zn2(O2CR)4]物种基态下扭曲的四面体配位，同时为更高对称性的D4h过渡态构象给出合理的结构和能量。锌-配体莫尔斯函数参考距离r0根据剑桥结构数据库中的30个配合物进一步优化，该力场应用于柔性金属有机框架（MOF）[Zn(bdc)2(dabco)]n（bdc = 1,4-苯二甲酸；dabco = 1,4-二氮杂双环(2.2.2)辛烷）的孔模型。单个孔模型可再现抽空的MOF系统的晶胞，而3×3网格模型对于与观察到的在吸附二甲基甲酰胺或苯时明显的结构变化取得良好一致性是必要的。
