Musical molecules

Ever wondered what cinnamic acid might sound like? Or caffeine, and water and a host of other common molecules? Now, scientists at Bradford University have got together with students from Ilkley Grammar School in Yorkshire to make music from molecules – by converting the vibrations of the constituent atoms into sound waves and using them to make musical tunes.

The technique relies on tuning into the vibrations of atoms as they stretch and bend within molecules, explains Nicolas Barry at the University of Bradford. It is these vibrations that are detected by the common analytical technique of IR spectroscopy in the laboratory – which gives each molecule its own unique chemical fingerprint.

Here, what the team has done is to convert these IR frequencies to audible ones, and then use their own creativity to interpret these sounds in a musical composition that reflects their own ideas and thoughts about each particular molecule.

‘Ten years ago, other researchers reported making music from protein folding, but as far as I know we are the first to use molecular bonds to make music,’ says Barry. The team has even come up
with a score for the chemical conversion of aniline to 4-bromoaniline, interpreted in dance by Canadian artist Dominique Girard.

The IR waves were converted to sounds by dividing the IR frequency by an artificial conversion factor (3.564), Barry explains. To date the group has put music to 10 molecules: CO2, H2O, polyethylene, caffeine, ethanol, aspirin, 4-bromoaniline, transdibenzalacetone, cinnamic acid, and phenylacetate. Inspired by the interest in the project, Barry and colleague William Martin now hope to extend the pool of molecules working together with a professional musician. ‘It would be fascinating to obtain the sound of molecules relevant to global challenges – eg drugs, pollutants – to sensitise the general public to particular issues,’ he says. ‘I am thinking of antismoking campaigns, or obesity campaigns, microplastics etc.’

Barry believes the technology could be of interest for advertising agencies and for those starting marketing campaigns. One strength of the project is the ability to add complexity, he points out. ‘Think about your coffee. If you add the frequencies of glucose to your caffeine/water, you obtain your sweet coffee. Add milk now, and here is your cappuccino. In perfumes, the sheer amount of molecules contained in one drop of the precious elixirs would be like a symphony.’

In terms of the work’s educational value, meanwhile: ‘This project allows a more tangible understanding about what our students are looking at when they start studying chemical spectra,’ says Ilkley Grammar schoolteacher Neil Garrido.

As for the best piece of molecular music, student Matthew says his favourite score is made by humble water. ‘The F5 spells out ‘water’ in Morse code and the E4 spells out H2O in Morse code. There is a motif of a dripping tap constantly dripping in the middle ground and a drone with drums.’

The work was supported by a Royal Society Partnership Grant and presented at the Royal Society summer science exhibition in London in July 2019, where visitors were also invited to play the peaks on the infrared spectrum.