Determination of the dehydration pathway in a flexible metal-organic framework by dynamic in situ x-ray diffraction.

Ian M Walton,Jordan M Cox,Cassidy A Benson,Eric D Sylvester,Travis B Mitchell,Yu-Sheng Chen,Shea D Myers,Jason B Benedict,Gage S Bateman

doi:10.1063/4.0000015

Abstract

Understanding guest exchange processes in metal–organic frameworks is an important step toward the rational design of functional materials with tailor-made properties. The dehydration of the flexible metal-organic framework [Co(AIP)(bpy)0.5(H2O)]•2H2O was studied by novel in situ dynamic x-ray diffraction techniques. The complex mechanism of dehydration, along with the as-yet unreported metastable structures, was determined. The structural information obtained by the application of these techniques helps to elucidate the important guest–host interactions involved in shaping the structural landscape of the framework lattice and to highlight the importance of utilizing this technique in the characterization of functional framework materials.

Highlights

Porous crystalline materials, such as metal–organic frameworks (MOFs), are of particular interest for their multitude of potential applications, which include the sequestration of carbon dioxide and other pollutants,[1,2,3,4,5] low-pressure fuel storage,[6,7,8] chemical separations,[9,10,11,12] catalysis,[13,14,15,16] and molecular switches.[17,18,19,20,21] Applications for these types of materials generally stem from their ability to uptake, exchange, and release guest molecules through their open pores and the void space those pores create
The structural information obtained by the application of these techniques helps to elucidate the important guest–host interactions involved in shaping the structural landscape of the framework lattice and to highlight the importance of utilizing this technique in the characterization of functional framework materials
Given the large structural change that occurs following the complete loss of the guest water molecules, various dynamic in situ SCXRD (DIX) experiments were conducted to establish the manner in which the guests were removed from the material and the impact of this process on the host lattice

Summary

Introduction

Porous crystalline materials, such as metal–organic frameworks (MOFs), are of particular interest for their multitude of potential applications, which include the sequestration of carbon dioxide and other pollutants,[1,2,3,4,5] low-pressure fuel storage,[6,7,8] chemical separations,[9,10,11,12] catalysis,[13,14,15,16] and molecular switches.[17,18,19,20,21] Applications for these types of materials generally stem from their ability to uptake, exchange, and release guest molecules through their open pores and the void space those pores create. The dehydration of the flexible metal-organic framework [Co(AIP)(bpy)0.5(H2O)]2H2O was studied by novel in situ dynamic x-ray diffraction techniques. In pursuit of the mechanisms of guest exchange in this material, the dehydration of assynthesized 1 was characterized by dynamic in suit x-ray diffraction (DIX) techniques.[30] we report the determination of the dehydration pathway in 1 and the single-crystal structures of this material as the dehydration process occurs.

Results

Conclusion