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, r0, 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.Graphical AbstractStructural simulations of a zinc paddlewheel metal organic framework reproduce the observed breathing behaviourElectronic supplementary materialThe online version of this article (doi:10.1007/s00894-016-2949-5) contains supplementary material, which is available to authorized users.

Surface Morphological and Chemical Features of Anticorrosion ZrO2–TiO2 Coatings: Impact of Zirconium Precursor

“…Various approaches have been applied to limit the harmful effects of this phenomenon, for example, cathodic protection or reducing the activity of the aggressive medium by application of different inhibitors [1][2][3][4][5]. Another possibility is to provide passive protection by creating a physical barrier between the metals and their surrounding environment by using (i) chromium (III)-based or chromium-free conversion films, (ii) painting, (iii) hot-dip galvanizing, (iv) nanosized ceramic oxide coatings, etc.…”

A Ligand Field Molecular Mechanics Study of CO2‐Induced Breathing in the Metal–Organic Framework DUT‐8(Ni)

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Dynamic Variation of Responsive Metal-Organic Frameworks toward Specific Stimuli

“…[40][41][42] Research interest was expanded to tailor building blocks to construct flexible MOFs showing dynamic motions, such as the breathing and gate-opening phenomena. Many researchers have investigated these dynamic motions occurring in various types of flexible MOFs, for example, MIL-53 43,44 , paddlewheel-based pillared MOFs [45][46][47] , constructed by cation clusters linked by multitopic carboxylate linkers. We designed a novel flexible MOF system using azamacrocycles ([NiL R ] 2+ , where R = the functional group of the pendant arm) as metal building blocks (Fig.…”