Securing the elusive structural details could lead to what might be termed an "odor of magnitude" improvement in models for predicting interactions between fragrances and their molecular carriers. The cooperative project involves researchers from International Flavors & Fragrances (IFF), based in New York City, and NIST.
Besides contributing in other ways to product performance, carrier molecules band together and enwrap fragrance ingredients. IFF Associate Research Fellow Chii-Fen Wang likens the structural arrangement to an onion. "We want to determine where the fragrance compound is located in the onion--in the center, for example, or in a particular layer--and how the structure of the compound changes," she explains.
Detecting how neutrons are scattered as they pass through a sample reveals the locations and shapes of fragrance and carrier molecules over time, information of great interest to Wang and her IFF colleague, Johan Pluyter. The cold (slowed-down) neutrons available at the NIST Center for Neutron Research are ideal probes, says NIST team member Steven Kline. These chilled subatomic particles have wavelengths that will enable the team to measure the structural details that it seeks, which are on the order of 1 nanometer to 100 nanometers.
This basic information, says Wang, can guide efforts to enhance models for formulating carriers that are optimized for specific fragrances and products. With more accurate models, fragrance chemists can, for example, sidestep undesired molecular changes that subvert a desired aroma.