Indiana University scientists have reported evidence for a new molecular structure. This is a chemical bond between two negatively charged molecules of bisulfate (which has the chemical formula HSO4). This bond has been dubbed a “supramolecule”, and its discovery, with two negatively charged ions coming together, overturns the established laws of chemistry.
Discussing this further, the lead researcher Amar Flood explains: “An anion-anion dimerization of bisulfate goes against simple expectations of Coulomb’s law.”
In chemistry, two monomer molecules linked by a strong covalent bond are referred to as a “dimer.” (this is a polymer is a chain of many monomers). With supramolecular chemistry, dimers are connected by many weak non-covalent bonds. A negatively charged particle is an anion.
With Coulomb’s law two molecules with the same charge create a repellent force that prevents chemical bonding. This is a little like trying to push two magnets with the same end together. The new find overturns this and gives evidence of negatively charged chemical bonds. The law was first published in 1784 by French physicist Charles Augustin de Coulomb.
So, as Professor Flood explains, the molecule exists: “the structural evidence we present in this paper shows two hydroxy anions can in fact be chemically bonded.” The researchers have called the molecule a cynostar macrocycle.
This surprising find is up down to, as the professor explains, “we believe the long-range repulsions between these anions are offset by short-range attractions.”
This is an interesting find in relation to the history of chemistry; beyond this there are potential and important practical applications. The applications with this molecule include rendering nuclear waste ‘safe’ and to facilitate the reduction of chemicals used in agriculture, especially chemicals that can contaminate water and kill fish.
Because of the ion-extraction properties of the molecule, it could be used to remove sulfate ions from the process used to transform nuclear waste into storable solids (a process termed vitrification). The process could also be used to extract harmful phosphate ions from environments such as polluted lakes.
The research has been published in the journal Angewandte Chemie International Edition. The study is headed “Anions Stabilize Each Other inside Macrocyclic Hosts.”
