Effect of Spin‐Crossover‐Induced Pore Contraction on CO₂–Host Interactions in the Porous Coordination Polymers [Fe(pyrazine)M(CN)₄] (M = Ni, Pt)

Abstract

Keywords: Metal-organic frameworks / Spin crossover / Density functional calculations / IR spectroscopy / Adsorption Variable-temperature in situ ATR-FTIR spectra are presented for the porous spin-crossover compounds [Fe(pyrazine)-Ni(CN) 4 ] and [Fe(pyrazine)Pt(CN) 4 ] under CO 2 pressures of up to 8 bar. Significant shifts in the ν 3 and ν 2 IR absorption bands of adsorbed CO 2 are observed as the host materials undergo transition between low-and high-spin states. Computational models used to determine the packing arrangement of CO 2 within the pore structures show a preferred orientation of one of the adsorbed CO 2 molecules with close O=C=O···H contacts with the pyrazine pillar ligands. The interaction is a consequence of the commensurate distance of [a]

Utilizing the Gate-Opening Mechanism in ZIF-7 for Adsorption Discrimination between N2O and CO2

“…In addition to gas–host interactions, it is well-known that the gas–gas intermolecular interaction may enhance the adsorption strength. , Therefore, we also evaluate the intermolecular interaction of the gases to see how these forces may affect the adsorption in ZIF-7. Considering the confinement effect due to the narrow pores in ZIF-7, it is reasonable to evaluate the intermolecular interaction by calculating the molecular dimer with linear configuration.…”

Strong Cooperative Spin Crossover in 2D and 3D FeII–MI,II Hofmann-Like Coordination Polymers Based on 2-Fluoropyrazine

“…Modulation of cooperativeness has been described for clathrate systems constituted of thiourea (M II = Pd, Pt), maleic anhydride (M II = Pt), and five-membered aromatic rings (furan, thiophene, pyrrole; M II = Pt) as guest molecules. In addition, the effect of the spin state on the adsorption of CO 2 , the stabilization of the LS state upon SO 2 adsorption, and the adsorption of H 2 and its catalytic ortho–para conversion in the pores have been recently investigated. The effect of host–guest interactions and its influence on the SCO behavior has also been a subject of interest from a theoretical point of view. ,,, Application of specific physical techniques have uncovered new important properties of {Fe­(pyrazine)­[M II (CN) 4 ]}.…”

A radical spin on viologen polymers: organic spin crossover materials in water

“…1 One way of achieving stimuli-responsive properties in organometallic complexes [2][3][4][5] is by invoking a change in the spin state of the metal upon a stimulus. Changes in spin states are often accompanied by large changes in materials properties, including changes in color, [6][7][8] infrared absorption and emission, luminescence, [9][10][11][12][13][14][15] crystallinity, 16,17 conductivity, and magnetism. [18][19][20][21][22] As a result of such property changes, spin crossover inorganics that change from low-spin configurations to high-spin configurations upon stimuli such as heating, find use in thermochromic paints 23,24 and mechanical actuators, 25,26 and hold promise for use in sensors, displays, and molecularscale memory storage devices.…”