Molecule of the Month
May 2024
From Inorganic to Biological Structures of Arsenic

Inorganic arsenate AsO43- is the most common and most dangerous freshwater pollutant involving arsenic. In the pH range 6.5 to 8.5 of freshwater, it exists in the protonated forms H2AsO4- and HAsO42-, offering potential as hydrogen bonding donor and acceptor.
We are investigating how these forms react with and bind to biological moieties such as amino acids, peptides, and proteins. So far, we could isolate hydrogen-bonded structures of the arsenic hydrogen oxyanions with arginine and histidine, whereas with cysteine a substitution reaction occurs to form a pyramidal molecule with covalent As-S bonds. Such structures have been unknown so far, and will guide us to understand the biological toxicity of arsenic and its compounds better.

This research is conducted in the group of PD Dr. Simon Grabowsky in collaboration with the groups of Prof. Dr. Jean-Louis Reymond and Prof. Dr. Achim Stocker at the University of Bern.


  • Y. Balmohammadi, S. Grabowsky;
    "Arsenic-Involving Intermolecular Interactions in Crystal Structures: The Dualistic Behavior of As(III) as Electron-Pair Donor and Acceptor"
    Crystal Growth & Design, 2023, 23(2), 1033-1048; doi:10.1021/acs.cgd.2c01195.