Electronic structure calculations are applied to the study of the properties of the Zeolite Imidazolate Frameworks (ZIFs) for gas capture of the greenhouse effect gases CO, CH and SF. Van-der-Walls complexes of these adsorbates with imidazole are explored considering the imidazolate rings simplest models for the study of the nature of host-guest interactions in ZIFs. The minimum energy paths for complexation are described by determining global interaction potential energy surfaces. The approach of SF to the imidazole can produce its decomposition due to heterogeneous catalysis. The number of the complex stable geometries, depending on the size and polarity of the adsorbate, makes more probable its adsorption. The calculations prove that capture by imidazoles is energetically favored for the three adsorbates, CO displays the largest ability for binding imidazolate rings and methane presents the larger number of structures. CH and SF can be expected to be strong competitors while the molecular size of SF can yield to important steric effects. The stability of three body complexes type CH-imidazole-CO and SF-imidazole-CO confirms the probability of simultaneous attachments. © 2016 Elsevier B.V. All rights reserved.

This research was supported by a Marie Curie International Research Staff Exchange Scheme Fellowship within the 7th European Community Framework Program under grant n° PIRSES-GA-2012-31754 and the FIS2013-40626-P project of the MINECO, Spain. The authors also acknowledge the COST Actions 1401 and 1405. S.D. acknowledges MAEC-ACID (Spain) for the grant.

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