Vasarenes – a Spin-off from Forensic Chemistry Research: Recognition and Precipitation of Alkali Fluorides from Aqueous Solutions

Ravell Bengiat, The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
Maayan Gil, The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
Asne Klein, The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
Benny Bogoslavsky, The Institute Of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
Shmuel Cohen, The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
Faina Dubnikova, The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
Guy Yardeni, Chemistry Department, Nuclear Reseach Center Negev, Beer-sheva, Israel
Israel Zilbermann, Chemistry Department, Nuclear Reseach Center Negev, Beer-sheva, Israel
Joseph Almog, The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel

Ninhydrin is a widely used reagent in forensic science for the visualization of latent fingerprints and in biochemical research of amino acids. A spin-off from its classic use has revealed its unique ability in forming 3-dimensional vase-shaped compounds, which were thus named vasarenes, in a facile one-pot reaction with polyhydroxy aromatics. An intriguing characteristic of these structures is their selective affinity, binding and precipitation of ion-pairs of type M⁺F^-, where M being a large monovalent cation.

Our recent research has involved the design and synthesis of new analogues that are water-soluble, from polycarbonyl componds other than ninhydrin.  The new ligands, which are readily obtained from alloxan (instead of ninhydrin) and polyhydroxy aromatics have shown a promising potential for the challenging task of binding and precipitation of highly soluble ion pairs, such as CsF, from aqueous solutions.

The ease of preparation of our receptors from accessible, inexpensive starting materials in a rapid and straight forward one-pot synthesis, as well as the specific affinity towards fluoride salts, indicates their applicability as a sustainable salts-separation tool for practical applications.