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Defect Engineering
in the Porous Salt CAU-55: The
Relationship between Cluster Defects and Sorption Properties
Bastian Achenbach (22652504)
Sabrina Grigoletto (25143757)
Iago Maye (25143760)
Alejandro Diaz-Marquez (25143763)
Mohammad Wahiduzzaman (1914607)
Norbert Stock (1414273)
Matthias Thommes (1584469)
Guillaume Maurin (1437943)
Biophysics
Biochemistry
Space Science
Medicine
Cell Biology
Evolutionary Biology
Environmental Sciences not elsewhere classified
Chemical Sciences not elsewhere classified
Sociology
observed sorption trends
framework remained unchanged
additional pores associated
widom insertion simulations
thermogravimetric measurements confirmed
missing acetate ligands
varying defect concentrations
increasing defect concentrations
sorption experiments revealed
273 k ),
porous salt cau
24 </ sub
2 </ sub
cl ([ al
missing al
porous materials
probe confirmed
molecular simulations
mofs ),
298 k
free cau
defect engineering
defect chemistry
well established
starting materials
powerful strategy
porosity arise
molar ratios
infrared spectroscopy
geometric characteristics
experimental findings
exclusively ultramicroporosity
elemental analysis
clear transition
adsorption capacities
adsorption behavior
Defect engineering has emerged as a powerful strategy
to tailor
the properties of porous materials. While defect chemistry is well
established for metal–organic frameworks (MOFs), the nature
and role of defects in porous salts remain unexplored. Here, we report
on the synthesis of the porous salt CAU-55-Cl ([Al<sub>24</sub>(OH)<sub>56</sub>(O<sub>2</sub>CCH<sub>3</sub>)<sub>12</sub>]Cl<sub>4</sub>), which exhibits different sorption properties due to varying defect
concentrations that can be achieved by adjusting the molar ratios
of the starting materials. Infrared spectroscopy, elemental analysis
and thermogravimetric measurements confirmed that the composition
of the framework remained unchanged, suggesting that variations in
porosity arise from cluster defects (missing Al<sub>24</sub> clusters)
rather than ligand defects (missing acetate ligands) in CAU-55-Cl.
Ar (87 K), N<sub>2</sub> (77 K), CO<sub>2</sub> (273 K), and H<sub>2</sub>O (298 K) sorption experiments revealed a clear transition
from exclusively ultramicroporosity for the defect-free CAU-55-Cl,
only accessible for H<sub>2</sub>O and CO<sub>2</sub>, to the presence
of additional pores associated with the presence of cluster defects,
leading to significantly higher apparent specific surface areas and
adsorption capacities with increasing defect concentrations. These
experimental findings were further corroborated by molecular simulations,
which revealed the geometric characteristics of cluster defects and
their influence on adsorption behavior. Grand Canonical Monte Carlo
(GCMC) and Widom insertion simulations of Ar as the probe confirmed
that missing clusters introduce larger, energetically distinct pore
environments, aligning with the observed sorption trends.
2026-09-30T00:00:00Z
Text
Journal contribution
10.1021/acs.langmuir.6c03585.s001
https://figshare.com/articles/journal_contribution/Defect_Engineering_in_the_Porous_Salt_CAU-55_The_Relationship_between_Cluster_Defects_and_Sorption_Properties/34032121
CC BY-NC 4.0