Designer fragrances might conjure up images of Calvin Klein and JLo, but chemists have added new meaning to the phrase by designing perfumes that provide a longer-lasting scent. 

Andreas Herrmann and colleagues at fragrance company Firmenich, Switzerland, and Université Louis Pasteur, France, have developed so-called profragrances that release perfume molecules in a controlled way. 

The researchers created a dynamic mixture of commonly-used fragrance molecules (aldehydes or ketones) and hydrazine derivatives, in equilibrium with the corresponding hydrazones. Once deposited on a surface, the volatile fragrance molecules evaporate from the mixture, shifting the equilibrium towards the hydrazine derivative. This continuous hydrolysis of the hydrazones to hydrazines results in a gradual fragrance release.

 

                    

© iStockphotos

 

'We tried to bring innovative basic science to the market place,' said Herrmann. 'So far, profragrances have had to be synthesised separately before being added to a consumer product. The development of dynamic mixtures obtained by reversible hydrazone formation now allows us to generate a multitude of profragrances in situ.'

Olof Ramstrom at the Royal Institute of Technology, Sweden, said the method was very promising for the fragrance industry. '[Hermann and co-workers] show that reversible bond formation can be used for controlled release of aldehyde fragrances. The release could be prolonged substantially, suggesting that the method is very efficient as a slow delivery system.' 

Herrmann said, 'we hope that this new technology may also influence future developments of delivery systems in other areas, such as the pharmaceutical or agrochemical industry.' 

Karen Rigby