Water-induced structural transformations in flexible two-dimensional layered conductive metal−organic frameworks

Document Type

Article

Publication Date

11-24-2020

Abstract

The flexible and ever-changing layered structure of electrically conductive 2D metal−organic frameworks (MOFs) poses a formidable challenge for establishing any structure−application relationship. Here, we employ a combined quantum mechanics and classical molecular dynamics approach allowing large-scale/ long-time simulations of the dynamics of both dry and hydrated systems to investigate the intrinsic flexibility and dynamical motions of layered 2D MOFs and its effect on their physical and chemical properties. Co3(HHTP)2 and Cu3(HHTP)2, HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene, MOFs as two representatives of the layered family of MOFs are studied in great detail with a focus on their experimentally observed differential framework stabilities in aqueous solutions. Our comprehensive molecular dynamics simulations reproduce structural properties of both MOFs as well as selective hydrolysis of the secondary building units with open metal sites in the hydrated Co3(HHTP)2 versus intact metal nodes in hydrated Cu3(HHTP)2 in agreement with available experimental reports. Our extensively detailed simulations reveal that the reason behind this behavior is the presence of intrinsic deformation sites in dry Co3(HHTP)2. Our accurate ωB97M-v quantum mechanical calculations further confirm the higher tendency of the open Co2+ sites for coordination to water molecules compared to Cu2+. Our multi-faceted strategy paves the way toward simulation of realistic MOF-based materials and their interface with confined water molecules, which is especially relevant to designing more robust water stable materials with desired properties and applications.

Identifier

85095747065 (Scopus)

Publication Title

Chemistry of Materials

External Full Text Location

https://doi.org/10.1021/acs.chemmater.0c03331

e-ISSN

15205002

ISSN

08974756

First Page

9664

Last Page

9674

Issue

22

Volume

32

Grant

CHE200007

Fund Ref

National Science Foundation

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