Cationic Conductive Aluminum Metal-Organic Framework Couples Ion Exchange and Redox Chemistry for Oxyanion Detoxification
Abstract
We report Al-HOTP, [Al 3 (HOTP) 2 (H 2 O) 6 ][Al 3 (HOTP)(H 2 O) 12 ] (SO 4 ) 2 (HOTP = 2,3,6,7,10,11-hexaoxytriphenylene), a cationic two-dimensional electrically conductive metal-organic framework (MOF) that couples counterion-exchange chemistry with a redox-active framework for oxyanion capture and detoxification. While triphenylene-based honeycomb conductive frameworks are well established, the Al-based analog reported here is, to the best of our knowledge, the first of its kind, and demonstrates how cationic ion-exchange chemistry can be combined with framework-mediated redox activity for multifunctional water remediation. Al-HOTP efficiently removes permanganate (MnO 4 − ) and dichromate (Cr 2 O 7 2− ) from water while promoting their conversion to lower-valent, less toxic Mn(IV)- and Cr(III)-containing species. The framework removes approximately 95% of MnO 4 − and 90% of Cr 2 O 7 2− from 30 ppm solutions within 5 min and exhibits an experimentally demonstrated uptake capacity of up to 1600 mg g −1 for MnO 4 − and 300 mg g −1 for Cr 2 O 7 2− . To the best of our knowledge, the MnO 4 − adsorption capacity is the highest reported for a MOF-based permanganate adsorbent. Mechanistic studies support a cooperative capture-and-reduction mechanism in which sulfate-to-oxyanion exchange promotes initial uptake, followed by electron transfer from the redox-active HOTP ligands to the captured oxyanions. The resulting framework oxidation increases the demand for charge-compensating anions, enabling additional uptake beyond the initial sulfate-exchange capacity. Beyond batch uptake, Al-HOTP maintains efficient contaminant removal over 36 consecutive filtration passes and can be integrated into an FTO-based electrode for proof-of-concept electrochemical detection of both oxyanions. Overall, this work establishes the coupling of permanent cationic character with framework redox activity as a design strategy for integrating high-capacity capture, reductive detoxification, regeneration, and device functionality for multifunctional water remediation.
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BibTeX
@misc{suman2026cationic,
title = {{Cationic Conductive Aluminum Metal-Organic Framework Couples Ion Exchange and Redox Chemistry for Oxyanion Detoxification}},
author = {Satya P. Suman and Christian Sandoval-Pauker and M. R. Dontireddy and Ahad H. Javed and Zina Deriche and Moneer Alenezi and Maria Elahi and Dino Villagrán and Thomas P. Senftle and Stavroula Alina Kampouri},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15009260/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009260/v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Cationic Conductive Aluminum Metal-Organic Framework Couples Ion Exchange and Redox Chemistry for Oxyanion Detoxification
AU - Satya P. Suman
AU - Christian Sandoval-Pauker
AU - M. R. Dontireddy
AU - Ahad H. Javed
AU - Zina Deriche
AU - Moneer Alenezi
AU - Maria Elahi
AU - Dino Villagrán
AU - Thomas P. Senftle
AU - Stavroula Alina Kampouri
PY - 2026
DA - 2026/09/22
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009260/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009260/v1
AB - We report Al-HOTP, [Al 3 (HOTP) 2 (H 2 O) 6 ][Al 3 (HOTP)(H 2 O) 12 ] (SO 4 ) 2 (HOTP = 2,3,6,7,10,11-hexaoxytriphenylene), a cationic two-dimensional electrically conductive metal-organic framework (MOF) that couples counterion-exchange chemistry with a redox-active framework for oxyanion capture and detoxification. While triphenylene-based honeycomb conductive frameworks are well established, the Al-based analog reported here is, to the best of our knowledge, the first of its kind, and demonstrates how cationic ion-exchange chemistry can be combined with framework-mediated redox activity for multifunctional water remediation. Al-HOTP efficiently removes permanganate (MnO 4 − ) and dichromate (Cr 2 O 7 2− ) from water while promoting their conversion to lower-valent, less toxic Mn(IV)- and Cr(III)-containing species. The framework removes approximately 95% of MnO 4 − and 90% of Cr 2 O 7 2− from 30 ppm solutions within 5 min and exhibits an experimentally demonstrated uptake capacity of up to 1600 mg g −1 for MnO 4 − and 300 mg g −1 for Cr 2 O 7 2− . To the best of our knowledge, the MnO 4 − adsorption capacity is the highest reported for a MOF-based permanganate adsorbent. Mechanistic studies support a cooperative capture-and-reduction mechanism in which sulfate-to-oxyanion exchange promotes initial uptake, followed by electron transfer from the redox-active HOTP ligands to the captured oxyanions. The resulting framework oxidation increases the demand for charge-compensating anions, enabling additional uptake beyond the initial sulfate-exchange capacity. Beyond batch uptake, Al-HOTP maintains efficient contaminant removal over 36 consecutive filtration passes and can be integrated into an FTO-based electrode for proof-of-concept electrochemical detection of both oxyanions. Overall, this work establishes the coupling of permanent cationic character with framework redox activity as a design strategy for integrating high-capacity capture, reductive detoxification, regeneration, and device functionality for multifunctional water remediation.
ER -