What’s in a bond? Everything, if it’s the amazing hydrogen bond which raises water’s boiling point high enough for a cuppa or binds the DNA into a double helix. Interestingly, the bond has been redefined and a new explanation of why hydrogen atoms build or break bridges with other atoms that has been arrived at could open up new avenues in production of drugs and fabrication of material among other things. Researchers are also looking forward to many more spin-offs with advances in this technology.
The changed definition of the hydrogen bond stems from research and analysis carried out by a team led by Prof Elangannan Arunan of the Department of Inorganic and Physical Chemistry, Indian Institute of Science and has been accepted by the International Union of Pure and Applied Chemistry (IUPAC). It will soon make its way into the Gold Book, the encyclopaedia of chemical nomenclature.
The Indian team's path breaking acheivement, which coincides with the International Year of Chemistry being observed by the United Nations General Assembly and the centenary of Marie Curie winning the Nobel prize for Chemistry in 1911, signals an end to the controversy over hydrogen bonding which was debated for decades after it was spelt out by Nobel laureate Linus Pauling in 1931. A number of previous efforts by task forces across the world were rejected because they either lacked experimental evidence or could not answer questions raised by the community of chemistists. “I had to pour over several research papers and scores of records on earlier definitions to be able to answer this controversial question. But at this point, it’s difficult to predict the upshot of our definition,” says Prof Arunan.
The breakthrough came at the end of five years of research which included building a microwave spectrometer to decipher why hydrogen builds bridges with other atoms or breaks them. “When we started our work, some were pessimistic that we would not be able to give a new definition because we had to refer to a 100 year-old history and scores of papers on the hydrogen bond,” recalls the professsor. Previously, the definition suggested that hydrogen bonds were ‘electrostatic interactions’ and that the hydrogen atoms bore a slightly positive charge that was attracted by a slightly negatively-charged bonding partner. The new definition, however, allows for an element of covalent bonding, where electrons are formally shared between the atoms.
Deccan Chronicle Dated July 13, 2011
No comments:
Post a Comment