title: Molecular modeling of zinc paddlewheel molecular complexes and the pores of a flexible metal organic framework.
abstract: 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.
authors.affiliation: Inorganic Computational Chemistry Group, University of Warwick, Coventry, CV4 7AL, UK.
authors.forename: Khalid A H
authors.initials: KA
authors.lastname: Alzahrani
authors.affiliation: Inorganic Computational Chemistry Group, University of Warwick, Coventry, CV4 7AL, UK. r.j.deeth@warwick.ac.uk.|School of Chemistry, Joseph Black Building, David Brewster Road, Edinburgh, Scotland, EH9 3FJ, UK. r.j.deeth@warwick.ac.uk.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Deeth
keywords: Force field; Metal organic framework; Molecular dynamics; Molecular mechanics; Transition metal complex