Water-Gated Molecular Bistability in Tetrazolate MOFs
Abstract
Stimuli-responsive metal–organic frameworks (MOFs) offer opportunities to couple structural transformations with switchable electronic states, yet reproducing spin-crossover (SCO) behaviour across different frameworks and metal centres remains challenging. Here, we demonstrate a conserved watergated switching mechanism in a family of flexible tetrazolate MOFs comprising Fe(II), Co(II), and mixed Fe/Co frameworks. Dehydration induces framework contraction, metal–N bond shortening, ligand immobilization, and a shift toward low-spin states, while rehydration restores the initial structure and physical properties. Remarkably, despite their markedly different initial spin-state populations, upon dehydration of Fe- and Co-based frameworks, Raman spectroscopy reveals an identical 13 cm-1 shift of a tetrazolate/phenyl-ring vibration, identified as a spin state marker band. This molecular fingerprint is also retained in the mixed-metal solid solution, demonstrating that the structural and vibrational response is conserved upon metal substitution and mixing. These results identify water desorption as the thermodynamic trigger, and the flexible tetrazolate network as the mediator that couples guest removal to metal-centre spin transition, providing a transferable strategy for water-gated spin switching in flexible tetrazolate frameworks.
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BibTeX
@misc{gullace2026watergated,
title = {{Water-Gated Molecular Bistability in Tetrazolate MOFs}},
author = {Sara Gullace and Ana Martinez-Martinez and César Fabro and Mar García Hernández and Oscar Fabelo and Fanny Richard and Paolo Samorì and Jorge Albalad and Daniel Maspoch and E. Carolina Sañudo and José Sánchez Costa and Jose Sanchez Costa},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15009018/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009018/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Water-Gated Molecular Bistability in Tetrazolate MOFs
AU - Sara Gullace
AU - Ana Martinez-Martinez
AU - César Fabro
AU - Mar García Hernández
AU - Oscar Fabelo
AU - Fanny Richard
AU - Paolo Samorì
AU - Jorge Albalad
AU - Daniel Maspoch
AU - E. Carolina Sañudo
AU - José Sánchez Costa
AU - Jose Sanchez Costa
PY - 2026
DA - 2026/09/17
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009018/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009018/v1
AB - Stimuli-responsive metal–organic frameworks (MOFs) offer opportunities to couple structural transformations with switchable electronic states, yet reproducing spin-crossover (SCO) behaviour across different frameworks and metal centres remains challenging. Here, we demonstrate a conserved watergated switching mechanism in a family of flexible tetrazolate MOFs comprising Fe(II), Co(II), and mixed Fe/Co frameworks. Dehydration induces framework contraction, metal–N bond shortening, ligand immobilization, and a shift toward low-spin states, while rehydration restores the initial structure and physical properties. Remarkably, despite their markedly different initial spin-state populations, upon dehydration of Fe- and Co-based frameworks, Raman spectroscopy reveals an identical 13 cm-1 shift of a tetrazolate/phenyl-ring vibration, identified as a spin state marker band. This molecular fingerprint is also retained in the mixed-metal solid solution, demonstrating that the structural and vibrational response is conserved upon metal substitution and mixing. These results identify water desorption as the thermodynamic trigger, and the flexible tetrazolate network as the mediator that couples guest removal to metal-centre spin transition, providing a transferable strategy for water-gated spin switching in flexible tetrazolate frameworks.
ER -