Defect Engineering in the Porous Salt CAU-55: The Relationship between Cluster Defects and Sorption Properties
5 affiliations
- 1Institute of Inorganic Chemistry, Kiel University Max-Eyth-Str. 2, 24118Kiel, Germany.
- 2Institut Charles Gerhardt Montpellier, Univ. Montpellier, CNRS, ENSCM, 34293Montpellier, France.
- 3Institution of Separation Science and Technology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstr. 3, Erlangen91058, Germany.
- 4Kiel Nano, Surface and Interface Science (KiNSIS) Kiel University Christian-Albrechts-Platz 4, 24118Kiel, Germany.
- 5Institut Universitaire de France, Paris75005, France.
Abstract
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 ([Al24(OH)56(O2CCH3)12]Cl4), 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 Al24 clusters) rather than ligand defects (missing acetate ligands) in CAU-55-Cl. Ar (87 K), N2 (77 K), CO2 (273 K), and H2O (298 K) sorption experiments revealed a clear transition from exclusively ultramicroporosity for the defect-free CAU-55-Cl, only accessible for H2O and CO2, 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.
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BibTeX
@article{achenbach2026defect,
title = {{Defect Engineering in the Porous Salt CAU-55: The Relationship between Cluster Defects and Sorption Properties}},
author = {Bastian Achenbach and Sabrina Grigoletto and Iago Maye and Alejandro Diaz-Marquez and Mohammad Wahiduzzaman and Norbert Stock and Matthias Thommes and Guillaume Maurin},
journal = {Langmuir},
year = {2026},
month = sep,
doi = {10.1021/acs.langmuir.6c03585},
url = {https://hal.umontpellier.fr/hal-05805696v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Defect Engineering in the Porous Salt CAU-55: The Relationship between Cluster Defects and Sorption Properties
AU - Bastian Achenbach
AU - Sabrina Grigoletto
AU - Iago Maye
AU - Alejandro Diaz-Marquez
AU - Mohammad Wahiduzzaman
AU - Norbert Stock
AU - Matthias Thommes
AU - Guillaume Maurin
PY - 2026
DA - 2026/09/30
JO - Langmuir
DO - 10.1021/acs.langmuir.6c03585
UR - https://hal.umontpellier.fr/hal-05805696v1
AB - 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 ([Al24(OH)56(O2CCH3)12]Cl4), 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 Al24 clusters) rather than ligand defects (missing acetate ligands) in CAU-55-Cl. Ar (87 K), N2 (77 K), CO2 (273 K), and H2O (298 K) sorption experiments revealed a clear transition from exclusively ultramicroporosity for the defect-free CAU-55-Cl, only accessible for H2O and CO2, 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.
SN - 0743-7463
SN - 1520-5827
ER -