There is a truly astonishing molecule that has puzzled scientists for decennium . Its name is azulene and it is known for its strikingly beautifulbluecolor . But it is its physical behavior that is utterly peculiar . It seems to stubbornly defy Kasha ’s rule , the rule that explain how fluorescence or phosphorescence shoot place .

This is an almost cosmopolitan rule . Assume you have a molecule in what is experience as the soil state of matter , its minimum push res publica . you may excite themoleculeto higher energy states , but the steps between each are not all the same . The first footstep will be bigger than the 2nd , the second bigger than the third , and so on .

This means that you need more energy to go from the ground state to the first aroused commonwealth , but only a short bit more from the first land to the second . When the process occur in reverse , energy is emitted – usually as luminance – as the atom drop from one state of matter to the next lowest , a bit like going down the stairs .

In fluorescence , we are in reality interested in the opposite effect . Light isabsorbed , the molecule are excited , and then they release light in another form as they go from an excited res publica to the ground body politic . Kasha ’s dominion say that the emission that we see always hap from the transition between the first frantic nation and the ground nation . That ’s because it is the spacious of the muscularity gap so is where a mote will stay excited the tenacious , releasing Department of Energy as light .

Azulene does n’t really seem to care about the fact that this rule is supposed to be universal . Itsfluorescenceis mostly observed from its second most excited horizontal surface to the ground state , and not from the first . Researchers believe they have finally work out why .

Azulene is an isomer of naphthalene , the traditional principal element of mothballs . It has the same chemical element , 10 carbon paper mote and eight hydrogen atoms , but arranged in a different way . Still it is , like naphthalene , an redolent chemical compound . This means that it has a ring - shaped structure and is extremely unchanging .

But it turns out that in its first delirious state , the molecule is actually antiaromatic , which means that is no longer stable . In fact , this excited state exists for just a one-trillionth of a second . The 2nd excited land instead hold up for a nanosecond , so 1,000 time longer – enough to pass off a photon .

This queer attribute of azulene turns out to be transferrable . This could lead to interesting applications involving illumination , maybe in photoelectric cell , to manage abstemious free energy as expeditiously as potential .

“ I care possibility that are so simple you could well project , think , and then put them to use . And that ’s exactly what we ’ve succeed in doing . We ’ve answered the query of why molecule behave in a certain mode , and we ’ve done it using a very dim-witted concept , ” senior author Tomáš Slanina , from the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences , said in astatement .

In nature , azulene is incur in the paint of some mushrooms , some devil dog invertebrates , and even in sure plant oils . A derivative compound comes from chamomile oil , and has been used in practice of medicine .

The study is put out in theJournal of the American Chemical Society .