Electronic Structure, Pore Size Distribution, and Sorption Characterization of an unusual MOF, {[Ni(dpbz)][Ni(CN)4]}n, dpbz=1,4-bis(4-pyridyl)benzene

Published

September 26, 2018

Author(s)

Winnie K. Wong-Ng, Izaak Williamson, Daniel W. Siderius, Jeffrey T. Culp, Yu-Sheng Chen, Lan Li, Matthew Lawson

Abstract

The monoclinic (Ni(L)[Ni(CN)4] (L= 1,4-Bis(4-pyridyl) benzene) compound (nick-name Ni-dpbz) is a flexible metal organic framework (MOF) which assumes a pillared structure with layers defined by 2D Ni[Ni(CN)4]n nets and dpbz ligands as pillars. The structure features an entrapped dpbz ligand that links between the open ends of four-fold Ni sites from two neighboring chains. This arrangement results in an unusual 5-fold pseudo square-pyramid environment for Ni and a significantly long Ni-N distance of 2.369(4) Å. Using Density Functional Theory (DFT) calculations, the different bonding characteristics between the 5-fold and 6-fold Ni’s were determined. We found that there is weak covalent bonding between the 5-fold Ni and N in the entrapped ligand, and the 6-fold Ni-N bonds provide effective electronic conduction. The disordered dimethyl sulfoxide (DMSO) solvent molecules are not bonded to the framework. The material has a single pore with a diameter of 4.1 Å. This pore includes approximately 55 % of the total free volume (based on a zero-diameter probe). The accessible pore surface area and pore volume were calculated to be 507 m2/g and 6.99 cm3/kg, respectively. The maximum amount of CO2 that can be accommodated in the pores after DMSO is removed was found to be 204 mg/g, agreeing with the results of adsorption/desorption experiments of about 220 mg/g.

Citation

Journal of Applied Physics

Volume

123

Pub Type

Journals

Download Paper

https://doi.org/10.1063/1.5025674

Keywords

flexible porous MOF, Ni(1, 4-Bis (4-yridyl)benzene)[Ni(CN)4], 5-fold coordinate nickel complex, charge distribution, pore size characterization

Citation

Wong-Ng, W. , Williamson, I. , Siderius, D. , Culp, J. , Chen, Y. , Li, L. and Lawson, M. (2018), Electronic Structure, Pore Size Distribution, and Sorption Characterization of an unusual MOF, {[Ni(dpbz)][Ni(CN)4]}n, dpbz=1,4-bis(4-pyridyl)benzene, Journal of Applied Physics, [online], https://doi.org/10.1063/1.5025674 (Accessed April 25, 2024)