In Search of the Reason for the Breathing Effect of MIL53 Metal-Organic Framework: An ab Initio Multiconfigurational Study.

Oskar Weser,Valera Veryazov

doi:10.3389/fchem.2017.00111

Oskar Weser, Valera Veryazov

Open Access

https://doi.org/10.3389/fchem.2017.00111

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Abstract

Multiconfigurational methods are applied to study electronic properties and structural changes in the highly flexible metal-organic framework MIL53(Cr). Via calculated bending potentials of angles, that change the most during phase transition, it is verified that the high flexibility of this material is not a question about special electronic properties in the coordination chemistry, but about overall linking of the framework. The complex posseses a demanding electronic structure with delocalized spin density, antifferomagnetic coupling and high multi-state character requiring multiconfigurational methods. Calculated properties are in good agreement with known experimental values confirming our chosen methods.

Highlights

Metal-organic frameworks (MOFs) are microporous crystalline solids built from inorganic metal centers linked by organic ligands
The results show especially that the size dependency is the same for both spin states
For the sake of comparison all potentials were transformed to their own zero point using the energy calculated in the reference structure. All potentials in both figures are well described by a harmonic potential

Summary

Introduction

Metal-organic frameworks (MOFs) are microporous crystalline solids built from inorganic metal centers linked by organic ligands They have a high area per volume, display large structural diversity and tunable chemical interactions. Flexible MOFs, called soft porous crystals (SPCs) (Horike et al, 2009), are a particular subclass with the possibility of large and reversible structural transformations while preserving all bonds These transformations, called “breathing,” can be induced by chemical adsorption of guest molecules, temperature changes and mechanical pressure. The name was derived from “Matriaux de l’Institut Lavoisier” where they were discovered (Millange et al, 2002) These solids are built from trivalent cations {CrIII, FeIII, AlIII} linked by dicarboxylic acids such as p-benzenedicarboxylate.

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