Upon testing different fragrances in a perfumery, the so-called top note, consisting of the most volatile odorants, is what characterizes a scent. These odorants determine the first and often most decisive impression of a perfume.
Blackcurrant, or cassis, scent is one of the most sophisticated and elegant fruity top notes, and is fashionable since “DKNY Be Delicious”. A team from the RWTH in Aachen (Germany) and Givaudan Schweiz AG has now taken a close look at the blackcurrant odorant Cassyrane. As the scientists led by Wolfgang Stahl and Philip Kraft report in the journal Angewandte Chemie, there are specific structural features that key the cassis scent.
In addition to their two classic scents, ”Cassis Base 345B” and ”Corps Cassis”, in April 2010 Givaudan introduced a new captive ingredient Cassyrane; this substance imparts a natural, juicy cassis odor with aspects of cassis sorbet upon the top note of a perfume. Cassyrane consists of different so-called isomeric molecules that are of identical atomic composition, but have different spatial arrangements.
When four different atoms are bound to a carbon atom, there are two different ways for these to be arranged relative to each other in space. These two possible structures are mirror images of each other. Natural substances often have several such chiral centers. In scents, each of the possible combinations, known as stereoisomers, can have a different odor that can also be more or less intense. Cassyrane has two chiral centers, which gives it four possible stereoisomers.
Because the cassis odor of the other cassis scents distinctly depends on the configurations of the molecules, the researchers wanted to investigate the scent properties of the individual Cassyrane stereoisomers. They also examined the stereoisomers of the dihydro derivative, a compound of nearly identical structure that also smells of cassis but is missing the double bond found in the Cassyrane molecule.
It was first necessary to synthesize pure forms of each stereoisomer by means of clever procedures. It turns out that not all of the isomers smell of cassis. In both compounds, an R configuration at carbon number 5 elicits a character reminiscent of Provencal herbs like rosemary, while isomers with the 5S configuration had the fruity odor of cassis. The stereocenter at carbon number 2 has a strong influence on the intensity of the odor.
A molecule is a flexible structure; its atomic groups can twist and bend in various ways relative to each other. The researchers wished to determine which of these spatial structures is preferentially adopted by each of these stereoisomers in the gas phase. They were able to achieve this by examining the molecular rotations by means of microwave spectroscopy and combining these results with quantum chemical calculations. When the calculated structures were overlaid with those of the stereoisomers in the classical scents the result was clear: a very specific configuration does seem to be important for the cassis character of the scents.Author: Philip Kraft, Givaudan Schweiz AG, Dübendorf (Switzerland), mailto:email@example.com
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201100937
The irresistible fragrance of dying vinegar flies
16.08.2017 | Max-Planck-Institut für chemische Ökologie
How protein islands form
15.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).
The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
16.08.2017 | Physics and Astronomy
16.08.2017 | Materials Sciences
16.08.2017 | Interdisciplinary Research