The University of Sheffield’sChemistry News Team

ResonanceIssue 7 | Autumn 2017

The Hidden Detective

The Magical World of Chemistry

The Golden Age of Poison

Resonance is now well into its 3rd year of existence and this is its 7th issue. It may have had a few facelifts over time, as new editors put their own stamp on it, but at its core it still encompasses all of

its original values.

When they created Resonance, Alex Stockham and Prof. Simon Jones wanted to use it as a platform to encourage communication between

people both inside and outside of the department. They wanted to bridge the boundaries between peer groups and to engage people’s curiosity. As

editor for the past two issues, I am proud to say that I have contributed to this vision by taking Resonance to Nanjing, allowing our colleagues over

5,000 miles away to be involved.

This new issue hosts a wealth of interesting articles as many new (and seasoned) contributors share their insights into stories from

the department and the wider scientific community. Zoe Smallwood finally reveals where lecture theatres 2-5 have disappeared to in the

final installment of the history of the department (pages 5-6); Jasmine Cotton assesses whether Harry Potter is a wizard or actually just a

budding chemist (page 3); and Greg Coppack addresses the question “Is it possible to study and work in science while maintaining one’s faith?”

(page 7).

This issue is my last as Editor and I just wanted to thank everybody who has been involved. I especially want to thank Joe Clarke for his continued

enthusiasm and support. He is the real protagonist in this story; undertaking the roles of graphic designer, co-editor and photographer!

I’ve enjoyed my time at the helm (I would never have had the opportunity to meet a Nobel Prize winner and an astronaut otherwise),

but I am now pleased to pass the baton on to the next generation of editors, Josh Nicks and James Shipp, and look forward to seeing their

unique input into the legacy of Resonance.

Happy reading.

Beth Crowston

t

EditorBeth Crowston

Design EditorJoseph Clarke

Contributing Authors

Joseph ClarkeBeth CrowstonJasmine CottonGreg CoppackRachel Mowll

Zoe SmallwoodMatt Watson

Copy Editors

Joseph ClarkeBeth CrowstonDr Grant Hill

Dr Anthony J. H. M. Meijer

The University of Sheffield’s Chemistry News Team

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Resonance is a biannual newsletter produced by chemistry students at the University of Sheffield. It aims to provide insights into unheard stories from the Department and to engage you with issues in the wider scientific world.

Resonance

Editorial Social Media CoordinatorHelen Elmes

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On the Cover In This Issue

The Magical World of ChemistryCan chemistry explain some of the magical objects and spells of the Harry Potter universe?

Editorial 1

The Magical World of Chemistry 3

The Golden Age of Poison 4

The History of the Department 5-6

Elemental Factfile: Iridium 6

Science and Faith 7

An Interview with Charles Stirling 8

News from the Department 9-12

The Hidden Detective:How Chemistry Catches Criminals

13-14

Chocolate: Beneath the Wrapper 15-16

Chemistry Funpage 17

13

4

Get in Touch

3

  chem-news@sheffield.ac.ukThe Hidden Detective: How Chemistry Helps Catch CriminalsThe chemistry of luminol can assist in the detection of blood. This and other scientific methods are employed to catch criminals, even performed by Sherlock Holmes.

The Golden Age of PoisonPoison is a common implement of murder in novels. One particular case in “Mysterious Affair at Styles” demonstrates Agatha Christie’s prowess for writing plausible fictional murders.

  http://bit.ly/2weV7M1www

The University of Sheffield || Resonance Issue 7 2

Contents

There are three main aspects in the wizarding world that can be explained by chemistry, these are: coloured fires, flames and sparks; special inks; transformations.

There are many mentions of coloured fires or flames in the Harry Potter series:

“... dragons comprised entirely of green and gold sparks were soaring up and down the corridors […] shocking-pink Catherine wheels five feet in diameter were whizzing lethally through the air”

On the other hand, the fireworks created by mere Muggles can easily be explained. In fireworks, the colours are produced by heating metal salts that emit characteristic colours. For example, an orange coloured firework could be due to the presence of the metal salt calcium chloride. The metal salts emit their characteristic colours because the atoms of each element absorb energy and release it as light of specific colours. The amount of energy each atom absorbs is specific to each element, hence the light emitted is specific to each element. Using the two equations: E=hν and c= νλ, (E is the energy, h is Plancks constant, ν is the frequency, c is the speed of light and λ is the wavelength) it is possible to work out the wavelength of light, and then thus determine the colour of light that will be emitted.

Ink chemistry appears many times during the Harry Potter series. One of the most famous appearances is the Marauder’s Map, which only allows the user to see the writing once it is activated with the correct words:

“He took out his wand, touched the parchment lightly, and said, “I solemnly swear that I am up to no good”. At once, thin ink lines began to spread like a spider’s web from the point that George’s wand had touched. [...] then words began to blossom”

Sadly, in the Muggle world ink doesn’t appear at the touch of a wand, however, it is still rather interesting. In a chemist’s view, ink is a colloidal system of fine pigment particles dispersed in a solvent. Ink pigments are both inorganic

and organic; most white inks contain titanium dioxide as the pigment, other inorganic materials such as clays are used as fillers or extenders. The closest Muggle example to the Marauder’s Map is invisible ink. Although invisible upon writing, the ink can be visualised using chemical reactions, or physical changes. One of the most common invisible inks is lemon juice. This is not initially visible to the naked eye, due to its composition of sugar, water, and citric acid. However, once the paper with the lemon juice applied to it is heated, the writing can become visible. This is due to the citric acid. In paper, the cellulose fibres can be degraded by citric acid – the glucose units in the cellulose chains are broken down by hydrogen ions, leaving one side of the unit stable and the other able to bind with a water molecule. This is a cycle that repeatedly weakens the fibres in the paper, allowing the paper to burn faster and with more ease. Thus, the section of paper with the lemon juice applied will burn faster than the rest of the paper, and show the invisible ink message.

The last example of the chemical links in Harry Potter are transformations:

“Goyle’s potion exploded, showering the whole class. People shrieked as splashes of the Swelling Solution hit them. Malfoy got a faceful and his nose began to swell like a balloon.”

One of the most famous chemistry experiments is elephant’s toothpaste. The basic idea behind this is that concentrated hydrogen peroxide will break down rapidly, due to the addition of a catalyst (potassium iodide, etc), into oxygen and water. The addition of soap to the reaction will cause the creation of foam, as the soap reacts with the water. As the peroxide decomposition occurs, this creates a high volume of oxygen that gushes out of the container. This oxygen pushes the foam out of the container, resulting in a large quantity of foam being released.

These are just three examples of the many in the Hogwarts world which show that Harry Potter is really just a chemist in training, using simple chemistry reactions or principles.

The Magical World of Chemistry

The wizarding world of Harry Potter has inspired a generation to read and appreciate literature. However, personally I believe that the series also inspired a generation of

budding chemists.

By Jasmine Cotton

3 Resonance Issue 7 || Autumn 2017

Feature

The Golden Age of Poison

Poison has long been a murder weapon of choice, both fictionally and in real life. There seems to be a morbid fascination surrounding the use of poison, one which has led to several murder mystery books adopting it as the murder weapon. But do they depict it accurately?

By Jasmine Cotton

One of the great murder mystery authors was Agatha Christie. Across more than 80 detective novels, she has killed off over 300 people, and at least 100 of those were murdered using poison. Christie uses a vast range of poisons in her detective novels, the chemistry behind which is more often than not accurate in its description.

The accuracy behind Christie’s chemistry can be traced back to her volunteer efforts during the First World War. At first, she volunteered as a nurse in Torquay, but later she was offered the chance to work in a pharmacy as a dispenser. During those times the prescriptions had to be prepared by hand, and in order to be qualified to do this, Christie had to pass a number of exams. For these, both a theoretical and practical knowledge of chemistry had to be studied. Thus, Christie would have had a vast knowledge of common medicines found in people’s homes, as well as how other prescription medicines or household chemicals would react with these. This knowledge allows Christie to spin a plausible plot, making her murder mystery books ever more thrilling.

One book in which Christie’s chemical knowledge is applied brilliantly, is her first-ever Poirot novel, “Mysterious Affair at Styles”, published in 1920. The basic plot line of this novel is the wealthy Mrs Inglethrop is found dead in her room one morning. The poison which kills her is found to be strychnine; a poison if given as a fatal dose, typically taking 15 minutes to act.

During the time that “Mysterious Affair at Styles” was written, strychnine was a common medicine. It was prescribed as a remedy for heart and respiratory complaints. Thus, it was common to see in most households. In the novel, strychnine was dissolved in water to make a tonic, one which Mrs Inglethrop took regularly. The question therefore arises, how did she ingest a fatal amount of strychnine? As mentioned above, lethal doses take around 15 minutes to act, so how was it that Mrs Inglethrop had suddenly died one morning long after taking this particular batch? Surely if this contained a lethal amount, then she should have died much sooner. This is where Christie demonstrates her aptitude for chemistry.

Through her studies to become a dispenser, Christie knew that the addition of a large amount of potassium bromide to strychnine bromide tonic would lead to the precipitation of strychnine bromide cystals. This is due to the common ion

effect; the reduction in the solubility of an ionic precipitate when a soluble compound containing one of the ions of the precipitate is added to the solution. This effect can be seen: a solution of strychnine sulphate in water is completely clear, but after addition of potassium bromide, crystals of strychnine bromide precipitate, see Figure 1.

Potassium bromide which was used was a common prescription medicine as well, one which the novel stated Mrs Inglethrop would occasionally take as a sleeping pill. Thus, the murderer had all of the necessary compounds to hand already. This is the chemistry behind the murder of Mrs Inglethrop. Once potassium bromide was added to the tonic, a lethal dose of strychnine would precipitate to the bottom of the solution. As long as the solution was not shaken, the lethal dose would be administered as Mrs Inglethrop reached the end of the tonic.

This is just one example of Christie exercising her chemistry prowess. Clues of her chemical knowledge can be found in her liberal poisons in other numerous novels. Just a few examples include white phosphorus in “Dumb Witness”; thallium in “The Pale Horse” and the infamous cyanide in several novels.

Figure 1: Showing a solution of strychnine sulphate in water on the left, and the solution of strychnine after the addition of potassium bromide on the right. It is clear that crystals have formed in the right hand beaker. Reproduced with permission from [4].

1. http://bit.ly/2vuD3Mk2. http://bit.ly/2uAdcE83. http://bit.ly/2vROaQz4. Die tödliche Brechnuss. Strychnin – Von der Isolierung zur

Totalsynthese, Klaus Roth, Chem. Unserer Zeit 2011, 45, 202–218. Chem. Unserer. Zeit. Copyright Wiley-VCH Verlag GmbH & Co. KGaA. Reproduced with permission.

Feature

The University of Sheffield || Resonance Issue 7 4

5 Resonance Issue 7 || Autumn 2017

The History of It’s probably one of the most asked questions within 1 and 6 are, but where are the others? Did they ever aside, the department has an extremely rich history

delved into the history books to see1954

Where were Lecture Theatres 2 - 5?

Lecture theatres 3 and 4 were located on D and E floor, directly above LT1, where research labs and write up

rooms now exist. Lecture theatre 4 overlooked one of the research labs on E floor, which proved particularly useful when a fire broke out in a neighbouring lab in the 1990s. Two lecturers, attending a seminar at the time, noticed what was going on and quickly scrambled out of their seats to extinguish the fire, thankfully before any major damage or injury was caused! Lecture theatres 2 and 5 were located in the old East Wing, on A floor (which is now the bottom of the Richard Roberts Auditorium) and D floor respectively, and were removed when the building was refurbished to become the Richard Roberts building in 2005. When they were removed, it was decided that changing the names of the remaining two would cause too much confusion, so LT6 retained its name.

A Family Connection.

One of our own technicians, Stephen Atkin, has a family connection to the department- his grandfather George

Dodsworth worked here for a year on an apprenticeship in the 1940s! He recalls the department being located in Firth Court before its move to the current site in 1954, with the chemicals being stored in the air-raid shelters which remained in the grounds following the war. He has kindly drawn us a floor plan (photo 1) of the old department, which shows a very different setup to the one we have now! Standard safety equipment such as goggles and lab coats were never worn in those days, with labs arranged around long wooden benches with no fume hoods. He also recalls a chain smoking organic chemistry professor, who was never seen without a cigarette!

Photo 1: A floor plan of the chemistry department when it was originally located in Firth Court in the1940’s.

Photo 2: Undergraduate laboratories circa 1945 when the chemistry department was still located in Firth Court.

Photo 3: Professor Wynne (centre) and the female chemistry team (1914-1918) responsible for the synthesis of the anaesthetic beta-eucaine.1

Insight

The University of Sheffield || Resonance Issue 7 6

The Departmental Community.

Although the first female academic appointments would not take place until almost half a century later, during

the First World War many female chemists were recruited to replace the men who were called up to serve. A team of Sheffield chemists were responsible for synthesising eucaine, a then-novel anaesthetic. The team’s contributions often resulted in appointments as technical and teaching assistants once the war had ended.1

As the building has changed over the years, so has the community itself. The department used to have segregated toilets for staff and students, postgraduates had their own common room in the East Wing, and the University Arms was a place where students were only permitted to enter

if they were in the company of a member of staff. The appointment of the department’s first female academic was in 1995 (our very own Prof. Jane Grasby). Nowadays, the department is the proud holder of an Athena Swan silver award for commitment to equality in science and the University Arms is open to all.

Staff numbers and their duties have also changed. In the 1970’s, there were approximately 70 technical staff, whose duties used to include picking up items from stores that researchers had ordered. This number has declined over the years to approximately 30 today, with the job of picking up items from stores now handed over to researchers.

the Departmentthe department. Everyone knows where lecture theatres exist, and where did they go? Mystery lecture theatres which dates back over 100 years. Zoe Smallwoodhow our department used to be.

2017

By Beth CrowstonElemental Factfile: Iridium

Iridium is a transition metal and is a member of the platinum family.

It has one of the highest densities of all of the elements on the periodic table (22.56 g cm-3) and is the most resistant to corrosion; being unaffected by acids and bases alike. However, it is particularly brittle which makes it difficult to machine or form. To combat this, the metal is heated to a white heat of 1,200 to 1,500 degrees Celsius to make it more amenable to work with. Its primary use today is to harden platinum by making an alloy.

Although in its pure form it is white in colour, as part of a co-ordination compound its colour can be tuned to span anywhere in the visible region of the electromagnetic spectrum. Hence, it is named after the latin word iris, meaning rainbow.

Pure iridium is incredibly rare, making up only 2 parts per billion of the Earth’s crust. However, in 1980 a significant amount of iridium-rich clay was found in a large buried crater with an estimated age of 66 million years. As

iridium has been found to be more abundant in meteorites such as the Willamette Meteorite (4.7 ppm),1 it was postulated that the crater was a product of an asteroid or comet impact. Due to the age of the crater, scientists have formulated the Alvarez hypothesis2

which posits that the mass extinction of non-avian dinosaurs was caused by this particular meteor strike.

1. http://bit.ly/2vRQqHt

1. http://bit.ly/2wFy10J2. http://bit.ly/2xtc2Y3

Photo 4: The undergrduate admissions team, circa 2002. From left to right:Peter Lee-Robichaud, Joe Harrity, Brian Taylor, Michelle Webb, David Williams, Patrick Fairclough, Lance Twyman, Jane Grasby, Graham Leggett, Ellen Heeley, Ahmed Iraqi, Andrew Maczek, Colin White, Sandra Marshall, Ihtshamul Haq, Ian Mclure.

Insight

Sc

ienc

e a

nd

Fai

thHistorically the two disciplines have been separate; even at war. In the modern era though, does

this have to remain true?

By Greg Coppack

Central to this matter is the following question: can the two institutions of scientific study and

faith (and all their subdivisions) coexist, and indeed work together, to further society in any way? Or are they conflicted to the point of being irreconcilable? When this was posited to the students, the responses were overwhelmingly in support of the former; one student pointed out that they are tools used to answer different questions. To many people, God represents a higher reasoning, a divine purpose for a seemingly incomprehensible teeming mass of humanity – in short, religion deals with the ‘why?’ questions. Science, on the other hand, seeks to explain the mechanisms behind the world in which we live – the ‘how?’. On this note, it was put to me that the two are not mutually exclusive at all: the world that we study through scientific methods and everything that we observe – evolution, the Doppler effect, respiration – could simply be the design of an omnipotent being.

It was ceded, however, that there are some points where scripture and science clash. For example, studies of the Earth’s geology estimate that our planet is 4.54 billion years old, while the Bible claims that God created the world between 6000-10’000 years ago. I decided to press this issue, questioning how the students drew the

line between what they believed in (regarding religious teachings) and the evidence proffered by scientific theories. The answers seemed to indicate that each individual’s belief set was comprised of what instinctively made sense and sounded correct rather than considering what was more likely.

It is plain to see that, while a few loud, fervent voices among atheist and religious communities would have you believe differently, the majority of rational people of faith see no reason why science and religion should conflict. Furthermore, whilst the role of organised religion may naturally diminish with time, it is not necessarily because people have abandoned it in favour of science, and undoubtedly it still has a large role to play. Ultimately, it can be said that there are very few occasions where science and faith are unreservedly in contradiction.

faith is on the decline, this answer suggests that a more fluid system of belief is beginning to

usurp organised religion.

1. http://bit.ly/2uSgptI2. © Crown Copyright 2006 Source: National Statistics / Ordnance

Survey Extracts are Crown Copyright3. (Islam was thought to be founded in the 7th century,

Christianity in the 1st)

Religion and science have not traditionally mixed. In 1633, Galileo was famously tried by the Catholic Church for publishing “Dialogue Concerning the Two Chief World Systems”, in which he offered his theory of heliocentrism (that the Earth revolves around the Sun). This directly contradicted biblical teachings – by claiming that the Earth was the centre of the Sun’s rotation. Galileo was branded a heretic and placed under house arrest after confessing under threat of torture. This was merely one clash under ‘The Inquisition’ – a wider campaign against scientific findings that rebutted Catholic scripture.1

Almost 400 years later, the influence of religion has waned: in the 2011 UK census, the percentage of people who deemed themselves to be ‘irreligious’ was 25.7 % (more than double the figure in 2001)2 and there are entirely secular countries (with no official state church) such as France, Australia and China. The UK, however, is directly linked to religion: Queen Elizabeth II is both Head of State and Supreme Governor of the Church

of England. Considering this, the fact that many scientists identify as religious/people of

faith is noteworthy, given that most

major religions are rooted in ancient history,3 an era far removed from science as we know it today. Is it possible to study and work in science while maintaining one’s faith?

It could be asserted that the decline in organised religion is a result of advances in science: as more answers to existential questions are provided, the fewer people may look to a higher power for those same answers. I interviewed several students within the chemistry department who practise religion with varying time commitments. All shared a familial religious background but agreed that they began to consider their religion as their own belief system between the ages of 12 and 14. Asking whether the recent deterioration in popularity of traditional religions was an indicator that they may one day become completely redundant, I received a particularly insightful answer:

“The need for complete open-mindedness and tolerance, while important, is becoming a belief in itself and seems to replace religion, which is an obvious threat.”

While the statistics show that commitment to a single

7 Resonance Issue 7 || Autumn 2017

Opinion

Charles’s interest in chemistry began at age 12. He was fascinated by the burning metal of a magnesium strip, and the intensity of the light produced encouraged him to learn more. Surprisingly, as a young boy he was not drawn in by the bangs of chemistry, but they would go on to play a role in his later career.

He began his journey into the world of chemistry in Scotland, obtaining his BSc from the University of St. Andrews, before heading to King’s College London to study for his PhD. Here, he shared a lab with Sir John Cadogan, a very influential scientist specialising in organic chemistry.

Soon after completing his PhD, Charles was obliged to undertake national service. He looked around enthusiastically for a non-barracks job and found that one of his options was a deferred job at the explosives department at Imperial Chemical Industries (ICI). However, his impression was tainted when he met the company research director who had a patch over an eye and his arm in a sling. This did not fill Charles with confidence and so his decision was “no”, but fortunately the government created a series of research fellowships at several research stations around the country, including atomic research and the Chemical Defence Establishment at Porton Down. Charles was interviewed for his role by the novelist Harry Hoff (pen name William Cooper) who immediately took a shine to him.

His eventual position at Porton Down allowed Charles a degree of free reign. However, his insistence not to be involved in hurting people was problematic in a department based around military research. Instead Charles worked on antidotes to nerve agents, which involved phosphorus chemistry, important to his future research career.

After national service, Charles was troubled by the common question: ‘do you go into academia or not?’ Charles wanted to stay in research, enjoying the unique life of a researcher. Happily, after his independent research at Porton Down he felt that he had proved to himself that he was capable of researching without a supervisor. Following a series of positions around the country, in 1990, he was offered a position at Sheffield, where he later became Head of Department. His research has focused on physical organic chemistry, with a particular emphasis on kinetics and

intramolecular interactions. Some of his best work has been conducted on strain in molecules, multi-layering on surfaces, and multiple low-energy interactions.

Charles has seen research in chemistry change massively over the years, notably with computers and NMR spectroscopy. He remembers using a 16 MHz NMR spectrometer, which when compared to today’s standard 400 MHz instruments, shows the amazing advancement that chemists have achieved. He predicts that the next big progression in chemistry will be a revolution in the synthesis of organic biologically important molecules.

But Charles has also witnessed the change in academic culture. As a big believer in equality, he felt that people should be evaluated exclusively on their skills and is happy with the changing landscape that has occurred over his life time with more female staff in the department and across the whole of academia.

His passion for chemistry has often led him into performing outreach for both school pupils and the public, which includes the prestigious accolade of delivering the Royal Institute Christmas Television Lecture. On the back of his outreach work he was awarded an Honorary Doctor of Science research degree from the University of Sheffield in 2007, for “raising the public understanding of science”.

An Interview with Charles StirlingProf. Charles Stirling FRS, has had a career in chemistry spanning many decades. He is a Fellow of the

Royal Society and was once the Head of this very department in which he now works as an Emeritus Professor in Prof. Nick Williams’ group. His current work is on surface chemistry based around calixarenes. Matt Watson spoke to Charles about his life experiences.

The University of Sheffield || Resonance Issue 7 8

Graduation Award for CharlesMore recently, at the end of this year’s graduation ceremony, a surprised Prof. Charles Stirling was awarded a special certificate for speaking as public orator at 100 graduations- by our calculations, approximately 9000 minutes or more than 6 days! After the ceremony, Prof. Stirling echoed the sentiments expressed by honorary graduate, first British astronaut and University of Sheffield alumna Dr Helen Sharman, advising all new graduates “to be on the lookout for new activities, new information, new opportunities and new outlooks on the world”.

Interview

9 Resonance Issue 7 || Autumn 2017

Originally hailing from Sheffield, Helen completed her BSc Chemistry degree here in 1984, before working for the General Electric Company and later Mars Confectionary, working on Mars Ice Cream bars amongst other treats. Upon answering a radio advert stating “astronauts wanted- no previous experience needed”, Helen was selected from 13’000 other applicants to travel to the Mir space station as part of Project Juno in 1991, which included a significant period of training in Star City, Moscow. Helen is now the Operations Manager in the department of chemistry at Imperial College London, and was interviewed on the 25th aniversary of her time in space as part of Issue 5 of Resonance in 2016.

Our very own Prof. Charles Stirling was the orator for Helen’s honorary degree in the ceremony, and spoke about her many contributions to outreach and the promotion of science and technology, including a book about space for children and being appointed as President of the Institute of Science and Technology. Charles also discussed the significance of her degree, saying: “in these days of cheap notoriety and shallow celebrity, Helen Sharman’s comments deserve attention…she has said “I would encourage everyone, aim high and have a go at a new experience””.

In her speech, Helen congratulated the new graduates, saying: “whilst today marks the end of an era of study for many of you, it is also the beginning of a new chapter in a world that is full of opportunities. A university qualification can be regarded as a proof of preparation; to use space terminology, it is a platform from which to launch into the future.” She spoke about her experiences of working in industry, including getting to taste chocolate every day

as part of her role in Mars Confectionary! She told the audience that she hadn’t thought about leaving, until she heard the radio advert recruiting astronauts and decided to “go for it”. Helen encouraged the graduating class to think beyond their qualifications and make the most of any opportunities that may arise. She said: “there are areas for us all to explore, if we remain open to learning, be

prepared to make the best of use of opportunity, and are confident to go for it.”

Helen’s speech ended with her encouragement to take whatever opportunities come your way, irrespective of whether it was on your planned track or not. She said: “my degree has shaped my life, but when I first graduated, I could not have known the opportunities it would have allowed me to explore.” She also revealed that Fraser Stoddart, one of the recipients of the 2016 Nobel Prize in Chemistry who paid a visit to the department a few months ago, was her personal tutor during her studies!

After the ceremony, Helen took the time to meet some of the Resonance team, and discussed what the department was like and what type of research the team were conducting. She also told us how she had come into a physical copy of Resonance containing our interview with her, after a colleague had picked up a copy in Nanjing that had

been taken out by Prof. Winter!

On behalf of Resonance we offer our congratulations to all the new alumni of the department, as well as to our latest award holders. We would also like to congratulate Helen Sharman on receiving her honorary degree and thank her for spending the time to talk to the team.

Helen Sharman returns to Sheffield

“Whilst today marks the end of an era of study for many of you, it is also the beginning of a new chapter in a world that

is full of opportunities.”

News from the By Zoe Smallwood

For more information: http://bit.ly/2tP30XT

On 20th July 2017, the graduating class of the department were joined by an honorary graduate with a difference- Helen Sharman, the first Briton in space.

News

The University of Sheffield || Resonance Issue 7 10

Department

Congratulations are extended to four members of staff who have recently been the recipients of awards for a variety of feats.

Dr Sarah Staniland is the recipient of the Suffrage Science award, which aims to recognise the achievements of women in science. This unique award is passed down from recipient to recipient acting as a scientific ‘relay’. Sarah’s award was passed down from Dr Lorna Dougan from the University of Leeds. “There is nothing more important than ensuring the great science of the future and diversity is key to this, so inspiring women to do and stay in a career in science is my great passion.”

Prof. Julia Weinstein is the recipient of the Royal Society of Chemistry Chemical Dynamics Award. This highly prestigious accolade is awarded for outstanding innovative research. Julia’s work focuses on understanding the processes of electron transfer.“It is an amazing feeling, it is such a high honour. I feel surprise, excitement, and immense gratitude to all the collaborators with whom we have been working together for many years.”

Dr Julie Hyde has become the latest recipient of a Senate teaching award for Sustained Excellence in Learning & Teaching. Julie has been instrumental in the success of teaching students in both Sheffield and those currently on the joint Sheffield Nanjing Tech BSc programme. “I am delighted to have been awarded the Senate Award. To be recognised for my dedication to chemistry over the years and for my laboratory teaching to students abroad whose first language is not English, as well as students at home, is wonderful.”

Prof. Steve Armes adds the European Colloid and Interface Science award sponsored by Solvay to an already extremely successful and prestigious academic career. This award is granted to a scientist who is judged to have conducted outstanding scientific research. Steve received this award for his work in the design of block copolymer nanoparticles using Polymerisation Induced Self-Assembly (PISA).

Academic Awards

Sir Fraser was invited back to Sheffield to deliver the Krebs lecture titled: ‘The Rise of the Mechanical Bond: From Molecules to Machines’ which followed his prestigious academic career from undergraduate chemist to Nobel Prize Laureate. A special poster session was also held in the department where postgraduates and 4th year students presented their own research to Sir Fraser. The session was then followed by a Q & A session where Sir Fraser described his experiences as an academic and memories of Sheffield.

2016 Nobel Prize laureate Prof. Sir Fraser Stoddart recently returned to the department where he worked for 19 years between 1971 and 1990.

Fraser Stoddart Visits the Department

and Joseph Clarke

For more information: http://bit.ly/2tP30XT For more information: http://bit.ly/2u4tiAqhttp://bit.ly/2n9WuEE

News

News

In 1967 these words accompanied the award of the Nobel Prize in Chemistry to Manfred Eigen, Ronald George Wreyford Norrish and former University of Sheffield professor, George Porter.1

2017 marks the 50th anniversary of this award, and is incidently the 15th

anniversary of his death. The now Lord Porter moved to Sheffield in 1955 where he remained until he moved to the Royal Institute in 1966.2

The Nobel Prize in Chemistry 1967 was awarded for the understanding of chemical kinetics. Chemical reactions chiefly rely on the formation of substances from reactants, but not all reactions are equal. While some can be measured with a rudimentary clock, others proceed at velocities which currently defy measurement with all but the most sophisticated technology. Take for example the process of electron transfer, which typically proceeds on the femtosecond timescale, 10-15 s or one quadrillionth of a second. To put it into perspective, a femtosecond can be said to form the same part of a second as a second is to 31 688 764 years!

The story of flash photolysis began in the 1940’s when Professor Norrish and his then associate George Porter

set out to study reaction kinetics by using a flash lamp. The idea was to have a system set up in an equilibrium, which is then disturbed by an external stimulus.3

The process of flash lamp photolysis is as follows: a substance is placed next to the lamp, which provides the stimulus required to excite the substance into an activated form or for molecules to be broken up. It is then possible to study these molecules spectroscopically. By the time George moved to Sheffield in

1955 he expanded on the uses of flash photolysis demonstrating its uses in organic and biological chemistry.4 Refinements to the method were made over the years, most notably with the discovery of the laser meaning shorter pulses could be performed recording picosecond timescales.

The importance of their method cannot be understated. Articulated perfectly by Nobel Prize presenter Prof. H. Olander:“Detailed knowledge of the behaviour of activated molecules was meagre and most unsatisfactory. Your Flash Photolysis method provides a powerful tool for the study of various states of molecules and the transfer of energy between them”.

Fifty years have passed since George Porter and Ronald Norrish developed Flash Photolysis. In this time their method has been used countless times to study kinetics and is still in use today. The advent of new improved technology may have lead to improvements in measurement speed and shorter timescale of study, but it still required the innovation and vision of the first pioneering researchers.

“For their studies of extremely fast chemical reactions, effected by disturbing the equilibrium by means of very short pulses of energy”

“Your flash photolysis method provides a powerful tool for

the study of various states of molecules

and energy transfer between them.”

The 1967 Nobel Prize: Fifty years later.

1. http://bit.ly/2vZ6jv22. http://bit.ly/2vguUIZ3. http://bit.ly/2wzf8xb4. J. Chem. Educ. 52, 1975, 703

(http://bit.ly/2w4yGGr)

Graduate Teaching Assistants, GTAs, form essential members of the department’s teaching team, providing support and instruction within laboratories or small group teaching in tutorials. Tom Roseveare, fourth year GTA, has recently been awarded as Fellow of the Higher Education Academy in recognition of his achievements in teaching. To achieve recognition, an individual must demonstrate their commitment to higher education by providing evidence of their commitment to high quality student teaching. Tom joins Dr Jamie Wright who last year became the first GTA to be awarded FHEA status. We would like to extend our congratulations to Tom on his fantastic achievement.

Tom Roseveare, postgraduate researcher in Prof. Lee Brammer’s research group has recently been recognised as a Fellow of the Higher Education Academy for his teaching contribution.

Tom Roseveare awarded FHEA status

11 Resonance Issue 7 || Autumn 2017

Kroto Day 2017

News

Instagram Competition2017 marked the department expanding its social media presence into the field of Instagram (@Sheffield.Chem). To mark the occasion, two competitions were held for postgraduate and undergraduate students to document photographs of interesting laboratory research or experiments. The winning photographs were those that achieved the most likes as voted by the channel’s followers.

The postgraduate award (left photo) was won by Dr Michael Walker, postdoctoral researcher in the Jim Thomas group, who photographed the yellow crystals of DPQ, a commonly synthesised compound in the group. The compound acts as a building block ligand and in conjuction with metals such as ruthenium, it can be used to produce fluorescent cell-imaging agents or can be used in therapeutic applications such as photodynamic therapy. Derived from 1,10-phenanthroline, DPQ can be made using nitrating mixes like those used to make gun cotton or explosives. Despite having access to millions of pounds worth of analytical equipment, you also know you’ve made it because it makes you sneeze!

The undergraduate competition was won by Milan Nakum who photographed the crystals formed from the synthesis of the organometallic sandwich compound ferrocene (right photo). The synthesis of ferrocene is a second-year undergraduate inorganic laboratory experiment. The reaction itself involves the reaction of cyclopentadiene with iron trichloride. The crude product is purified using vacuum sublimation, which avoids the product decomposing.

Kroto Day is an anuual outreach workshop in memory of the internationally renowned Nobel Prize winning chemist and University of Sheffield Alumnus Prof. Sir Harry Kroto. This workshop welcomed over 30 year 7 pupils from Chaucer Academy to learn more about the research that Sir Harry was awarded his Nobel Prize in Chemistry in 1996: the discovery of the buckminsterfullerene, also known as buckyballs.

Buckminsterfullerene is an allotrope of carbon, and stands alongside the other traditional forms of carbon; graphite and diamond. Buckyballs are formed from 60 carbon vertices made entirely out of pentagonal and hexagonal faces and as its nickname suggests, is shaped like a traditional football. In 2010 the breakthrough was named by fellow academics as one of the 10 most important discoveries made by their peers at UK universities in the past 60 years.

The workshop involved PhD students Matt Watson and Beth Crowston discussing the scientific scale. They encouraged students to think about the relative sizes of objects and how they all fit onto a single scale, from nanometres and smaller, for the sizes of molecules and atoms, to gigametres and beyond, reaching the sizes of planets.

The highlight of the workshop was for pupils to build their own buckyball using a specially provided kit. This hands-on approach gave students the opportunity to visualise the symmetrical arrangement of carbon atoms in the buckyball. Both activities allowed students to learn more about the interesting properties of the buckyballs and how these properties relate to other carbon allotropes such as graphite (layered carbon sheets used in pencils) and diamond. It also introduced concepts in mathematics and chemistry, laying the foundations for future inspiration and enthusiasm in studying science.

Left, winning postgraduate photo of DPQ crystals and right winner of the undergraduate competition, crystals of ferrocene

The 14th of June saw the university hold the annual Kroto Day, an outreach workshop to inform pupils about the internationally recognised research by the late Prof. Sir Harry Kroto.

The University of Sheffield || Resonance Issue 7 12

13 Resonance Issue 7 || Autumn 2017

From Sherlock Holmes to the modern criminal sleuths of today, the entertainment world loves a good crime thriller. In recent years, the world of forensic science has been cast into the spotlight in several TV

shows. These programmes often depict glamorous people shining UV lights in dark rooms and, inevitably, catching the culprit (usually with a witty pun or catchphrase to go with it). These scenes make for great television, but how accurate are these depictions and how much chemistry is involved?

One of the most common scenes from forensics shows is the detection of latent (i.e., invisible to the naked

eye) blood that someone may have tried to clean away. First, the area needs to be treated with a visualiser to allow any blood traces to show up. The visualiser reacts with the blood and emits a glow which can then be seen and photographed (although the glow is much shorter-lived than depicted on screen). Where there is no blood the area remains dark. The traditional choice of visualiser is luminol (figure 1) which is activated using an oxidising agent to allow it to glow upon contact with blood. When exposed to the iron in haemoglobin, it acts as a catalyst, enhancing the rate of reaction between luminol and the hydroxide ions used to activate it. This reaction releases energy as photons, resulting in a blue glow.1,2,3 However, blood is not the only thing luminol will glow upon contact with; other candidates include urine, iron metal and horseradish! This means that the results must be interpreted carefully to determine if it is blood that is present. Luminol also glows upon exposure to bleach, which may be a useful clue in itself if a clean-up operation has been performed at a crime scene before the detectives arrive. However, it can also damage DNA evidence before recovery, so only a small area may be treated at first.1,2,3

Another key piece of evidence in a forensic trail is fingerprints. Patent (visible) fingerprints are easy

to spot and examine as you will know if you have ever touched wet paint or ink. However, latent fingerprints need a bit more work to be visualised and recorded. Our fingers

naturally secrete oils, which are transferred to surfaces when we touch them. Depending on the surface they are on, fingerprints can be enhanced or revealed by dusting with fine powders that stick to the oils. Different surfaces require different types of powder, so a wide range exist for the correct scenes. But what if the surface is porous, like paper from a ransom note? This is where powders give way to a compound called ninhydrin (figure 2).

Often dissolved in a volatile solvent such as ethanol or acetone, ninhydrin is sprayed onto a surface and the solvent allowed to evaporate. When the hydroxyl groups in ninhydrin react with the terminal amine groups in the amino acids and proteins in the fingerprint residue, a dimeric compound is formed which is purple-red in colour, clearly showing where the fingerprint lies (figure 3). If there are no proteins or amino acids to react with, the residue remains colourless when the solvent evaporates.4

Lorem ipsum dolor sit amet, lacinia congue nunc turpis, feugiat amet eget nullam nulla ac et, eros est mi donec duis fermentum aliquet, mauris eget magna habitant. Fusce donec nonummy metus turpis, dolor faucibus faucibus at. Leo ipsum magna vestibulum, senectus non ut, dui massa a sed ipsum ac suscipit, integer iaculis vestibulum ante rutrum pellentesque, sed accumsan eu molestie. Sed varius pretium, mauris adipiscing dapibus venenatis nullam. Rhoncus class excepturi neque eget, amet neque laoreet sagittis lorem consequat, lacus adipiscing sed. Viverra nam cras in diam, amet ante ipsam magna, aliquam id sit fusce lorem magna enim, velit nisl curabitur lectus sit diam neque, ligula libero donec ipsum ut pellentesque duis. Lacus viverra rutrum turpis sed, lacus amet porta montes mauris volutpat eu, class vel. Nullam ipsum sit, suspendisse neque urna augue lacus id. Enim id. Libero at. Porta dui consectetuer, nunc metus, lectus molestias dolor, ornare id sagittis, hendrerit posuere mi proin eleifend placerat. Sit vel, quam nonummy nibh lorem litora, pellentesque lectus vestibulum eleifend neque quam facilisis.

Et risus consectetuer adipiscing maecenas vitae arcu, ipsum pulvinar, nascetur fusce aenean commodo condimentum maecenas ligula, nulla id aliquet volutpat, interdum vitae. Lobortis assumenda donec id nisl in, sapien vitae eget metus id eget, turpis tortor maecenas do eu gravida vel, elit molestie pharetra adipiscing duis augue, dolor ultrices. Ipsum lorem malesuada, mi tortor, nisl erat, vestibulum sed vivamus pretium, vitae erat id volutpat et. Sem in et urna aliquet justo gravida, quis tempus non urna sed. Euismod quam nam aliquet, justo eget sit lacus, et mi mauris consectetuer tempor sed elit, vestibulum ac in ipsum integer vivamus habitasse. Magna neque malesuada in in congue etiam, urna placerat dolor, leo venenatis magna mi tempor ipsum augue, quam gravida felis malesuada aliquam pharetra lacus. Mauris et, vel odio augue vivamus nibh, elementum morbi morbi phasellus, quam justo donec nonummy orci nec. Mauris tellus eleifend semper ornare enim. Vestibulum bibendum turpis etiam scelerisque aliquid venenatis, mauris fermentum eu feugiat, nullam pede pede tempor. Eros et donec. Placerat magna quis donec, ad pede erat sed.

Malesuada ligula odio turpis hendrerit. Tristique sem potenti porttitor massa eget, leo metus sed id vel libero volutpat, at ut fusce neque nulla lorem nullam. Massa odio cras mi vivamus maecenas scelerisque, a blandit nunc lorem dignissim ante ipsum, mattis sem risus interdum blandit convallis neque, nulla in praesent metus luctus leo vel, eget tellus sociosqu mollis mollis at. Eget malesuada quam sit semper justo nam, pellentesque ut id luctus nec lacus, quam quisque dictumst vitae nulla rutrum praesent. Felis wisi imperdiet quisque nec laborum, donec id maecenas et posuere dignissim mattis, lorem dolor pulvinar ultricies ut elementum mauris, neque nam penatibus quis sit aliquam. Sed lectus dolorem morbi inceptos amet, iaculis convallis magna velit lorem orci orci, eu tellus urna leo duis ligula, pede maecenas neque imperdiet et tellus platea, rhoncus urna est lacinia nunc fusce ante. Arcu amet aliquam eu parturient ac, lobortis ornare feugiat mattis in vulputate nunc, euismod id vestibulum eget etiam augue rhoncus, quis eos sem turpis eget fringilla. Et mi in lacus nibh in penatibus, duis curabitur mauris class cum convallis sit, sollicitudin Mollis elit morbi cras sed donec, dui elementum pellentesque erat sapien euismod, imperdiet turpis quam elementum nec justo ac. Lobortis assumenda donec id nisl in, sapien vitae eget metus id eget, turpis tortor maecenas do eu gravida vel, elit molestie pharetra adipiscing duis augue, dolor ultrices. Ipsum lorem malesuada, mi tortor, nisl erat, vestibulum sed vivamus pretium, vitae erat id volutpat et. Sem in et urna aliquet justo gravida, quis tempus non urna sed. Euismod quam nam aliquet, justo eget sit lacus, et mi mauris consectetuer tempor sed elit, vestibulum ac in ipsum integer vivamus habitasse. Magna neque malesuada in in congue etiam, urna placerat dolor, leo venenatis magna mi tempor ipsum augue, quam gravida felis malesuada aliquam pharetra lacus. Mauris et, vel odio augue vivamus nibh, elementum morbi morbi phasellus, quam justo donec nonummy orci nec. Mauris tellus eleifend semper ornare enim. Vestibulum bibendum turpis etiam scelerisque aliquid venenatis, mauris fermentum eu feugiat,

The hidden

deTecTive: how chemisTry helps caTch criminals

Figure 1: Chemical structure of luminol.

Figure 2: Chemical structure of ninhydrin.

Figure 3: Dimeric product from the reaction of ninhydrin with protein and amino acids in fingerprint residues.

By Zoe Smallwood

Feature

Before the development of the state-of-the-art analytical instrumentation that we use today, the field of forensic

science had to cope with cruder methods. In the 1800’s, arsenic trioxide, As2O3, was considered an effective and almost undetectable method of poisoning someone. The compound was odourless and poisoning gave symptoms similar to cholera, a common disease at the time. These properties meant the compound became known as ‘inheritance powder’ due to its use to dispose of spouses and family members! This was until a London chemist by the name of John Marsh was asked to investigate a case suspected to involve arsenic poisoning. Marsh used hydrogen sulphide, H2S, to detect the presence of arsenic. Unfortunately, by the time the trial came around the test results had decomposed, resulting in the jury declaring the defendant innocent. Sometime afterwards, the defendant confessed to the killing, which motivated Marsh to improve his test so the same mistakes would not happen again. He constructed a setup which involved reacting a sample of body tissue with zinc and acid.

As2O3 + 6H2SO4 + 6Zn → 2AsH3 + 6ZnSO4 + 3H2OEquation 1. Synthesis of arsine gas (AsH3) from As2O3.

Poisoned tissue would produce arsine gas, AsH3, which could be ignited to leave behind a stable black residue that would not decompose over time.

2AsH3 → 3H2 + 2AsEquation 2. The combustion of AsH3.

Although the improved test came too late to convict the killer, the Marsh Test (as it came to be known) became a common test for arsenic poisoning and arsenic trioxide’s status as a near-perfect poison came to an end.5

One of the most famous forensic scientists of all time is suprisingly Sir Arthur Conan Doyle’s character

Sherlock Holmes. Despite being a fictional character in stories published in the 19th century, some of the science and forensic work that Holmes conducts in his cases was not too far from the cutting-edge forensics of the time. It raised awareness of the application of science and chemistry to catching perpetrators and exonerating innocent parties. For example, his first use of fingerprint analysis was in 1890, 21 years before Scotland Yard began using the technique!6 To commemorate his contribution to chemistry, the Royal Society of Chemistry presented him with an honorary fellowship; the first (and currently only) fictional character to receive one. Although Holmes was obviously not able to receive his medal in person, the award was presented by none other than a Northern Irish chemist by the name of Dr John Watson.7

Lorem ipsum dolor sit amet, lacinia congue nunc turpis, feugiat amet eget nullam nulla ac et, eros est mi donec duis fermentum aliquet, mauris eget magna habitant. Fusce donec nonummy metus turpis, dolor faucibus faucibus at. Leo ipsum magna vestibulum, senectus non ut, dui massa a sed ipsum ac suscipit, integer iaculis vestibulum ante rutrum pellentesque, sed accumsan eu molestie. Sed varius pretium, mauris adipiscing dapibus venenatis nullam. Rhoncus class excepturi neque eget, amet neque laoreet sagittis lorem consequat, lacus adipiscing sed. Viverra nam cras in diam, amet ante ipsam magna, aliquam id sit fusce lorem magna enim, velit nisl curabitur lectus sit diam neque, ligula libero donec ipsum ut pellentesque duis. Lacus viverra rutrum turpis sed, lacus amet porta montes mauris volutpat eu, class vel. Nullam ipsum sit, suspendisse neque urna augue lacus id. Enim id. Libero at. Porta dui consectetuer, nunc metus, lectus molestias dolor, ornare id sagittis, hendrerit posuere mi proin eleifend placerat. Sit vel, quam nonummy nibh lorem litora, pellentesque lectus vestibulum eleifend neque quam facilisis.

Et risus consectetuer adipiscing maecenas vitae arcu, ipsum pulvinar, nascetur fusce aenean commodo condimentum maecenas ligula, nulla id aliquet volutpat, interdum vitae. Lobortis assumenda donec id nisl in, sapien vitae eget metus id eget, turpis tortor maecenas do eu gravida vel,

1. http://bit.ly/2vSvjF22. http://bit.ly/2wUkb7e3. http://bit.ly/2uAcGpu4. http://bit.ly/2uAeQpi5. http://bit.ly/2wGMBCr6. http://bit.ly/2uDa6ea7. http://bbc.in/2vS4PmS

The University of Sheffield || Resonance Issue 7 14

Feature

At some point during our time studying science, most of us will learn a little about the chemistry of chocolate. As a topic it clearly has a wide appeal and is a good example of the applications of chemistry

in everyday life. However one of the aspects of the chemistry of chocolate that I was not so familiar with from my studies is what interesting compounds it contains and what properties and effects they have. Is there a reason why we love it so much?

Indeed the chemistry of chocolate is surprisingly complex and teaching is often focussed on the manufacturing process, including the all-important process of tempering. Anyone who has watched the The Great British Bake Off will be familiar with this technique on a small scale, and as chemists we know that it is also performed on an industrial scale in the manufacture

of chocolate. Its purpose is to ensure that the fat molecules from the cocoa butter solidify in the correct polymorph to give chocolate with the correct melting temperature.

Chocolate has long been known to make us feel good and is even considered by some to be an aphrodisiac. There are a few

compounds present in chocolate which have been linked to this feel-good effect. However, is there any evidence for it or is it just wild speculation? Most of these claims are centred on molecules involved in the production and/or regulation of the neurotransmitters serotonin and dopamine in the brain, both of which are linked to feelings of happiness.

Phenylethylamine is present in chocolate at the relatively high level of 0.4 - 6.6 μg/g. When it occurs naturally in the brain it produces positive feelings by releasing dopamine and serotonin. It is even classed as a hallucinogen and is said to produce a high similar to ecstasy. However, when ingested in chocolate it is likely to be broken down before it can pass into the central nervous system, making it unlikely to be responsible for chocolate’s feel-good properties.

Tryptophan is an essential amino acid, meaning that humans are unable to synthesise it ourselves and must obtain it from food sources. It is a precursor in the synthesis of serotonin, so could clearly be linked to feelings of happiness. However, while chocolate can contain around 1300 μg/g, many other foods (often those containing high levels of protein in general) contain much higher levels, and indeed white flour contains the same quantity. It’s hard to imagine anyone snacking on a bag of flour to cheer themselves up. Like phenylethylamine it is also unlikely to enter the central nervous system unmetabolised after being ingested in chocolate and therefore probably isn’t the source of feel-good properties.

Chocolate: Beneath the Wrapper

Chocolate also contains some of the diverse range of chemical structures known as Cannabinoids, the compounds responsible for the high produced by cannabis. Again, these compounds are also found naturally in the brain and are present in chocolate in such tiny amounts (0.05 μg/g) that they are unlikely to have any effect.

By Rachel Mowll

15 Resonance Issue 7 || Autumn 2017

Research

There are over 400 compounds in chocolate that have been identified and only a small number have been covered here. Upon googling ‘chemistry of chocolate’ to research this article I discovered a number of suggested google searches along the lines of ‘is chocolate a mixture or a compound’, or ‘is chocolate a pure substance’. I’ll admit that the thought of chocolate being a single compound (and the thought that some people would ask that question) did amuse me slightly, however I firmly believe that the reality is far more interesting.

The flavour of chocolate comes from the cacao bean. Returning

to the manufacturing process, cacao beans are fermented and proteins in the beans are broken down to amino acids. Then the beans are roasted, during which time some unpleasantly flavoured volatile compounds evaporate and a cascade of reactions occurs between the amino acids and sugars. These reactions produce a range of molecules including aldehydes, esters, ketones and furans which give flavour and colour.

As for the fats, the fatty acid molecules found in chocolate come from cocoa butter and are palmitic acid, stearic acid and oleic acid. The first two are saturated fatty acids while oleic acid is unsaturated, giving it a kinked structure which affects the packing of molecules and therefore the melting point of the chocolate. For this reason the proportions of the fatty acids are varied by manufacturers to give an optimum melting temperature. The previously mentioned six different polymorphs of cocoa butter have different melting temperatures, with form V being preferable with a

melting point of 33.8 oC. This means it will melt in the mouth but not when stored at room temperature.

Of course, commercial chocolate does contain additives. For example, vanillin, the compound responsible for giving vanilla its flavour, is commonly used. It is anecdotally reported that American chocolate tastes sour, or even ‘like sick’! Interestingly, American brands often use butyric acid as an additive to give chocolate a sour note. So that mystery may be solved.

66% of chocolate is eaten between meals with 22% eaten between 8pm and midnight.

White chocolate is not technically chocolate due to the absence of

cocoa solids and chocolate liquor.1842, the year Cadbury created the first chocolate bar.

Nearly 70% of the world’s cocoa supply comes from Africa.

The Ivory Coast is the largest single producer of

the world’s cocoa.

1875, the year Daniel Peter from Switzerland created milk chocolate.

One psychological effect chocolate is known to have is as a stimulant. It is well known that it contains caffeine, with 100 g of chocolate containing an amount comparable to a cup of tea. And while caffeine may not exactly make you happy it may provide a boost to those in need of energy.

Chocolate also contains a related but less well-known stimulant, theobromine. As a chemist it is easy to assume that this compound contains bromine, but the name actually comes

from the name of the Cacao Tree from which cacao beans are harvested, Theobroma Cacao. Incidentally, Theobroma literally means ‘food of the gods’. Theobromine is structurally similar to caffeine, with just one methyl group removed.

Theobromine is also responsible for another property of chocolate, its toxicity in dogs. While it is also toxic to humans in high enough doses, it would be near impossible for even a real chocoholic to eat enough

chocolate for this to be dangerous. However this is not the case for dogs with the theobromine in chocolate causing nasty symptoms such as nausea and vomiting, diarrhoea, seizures, heart attacks and even death.

As should be becoming obvious, it’s unlikely that there’s one psychoactive compound in chocolate that makes it so popular. It is probably more to do with the high sugar and fat content, as well as the distinctive flavours and smooth, creamy textures.

The University of Sheffield || Resonance Issue 7 16

Article References:http://bit.ly/2uDf8HEhttp://bit.ly/2uSsoaPhttp://rsc.li/2vRRECD

http://bit.ly/2w0WVZ8http://bit.ly/2w14m2zhttp://bit.ly/2fBHWxP

Chocolate Facts:http://bit.ly/2uCPe72http://bit.ly/2hVmuo5

Research

Chemistry FunpageAcross:

3. A dumb-bell shaped space in which to find an electron (1,7)4. In the iron atom, in which numbered shell are the outer s-electrons (4)5. Not so much a bore, more an enlightened scientist (4)6. A pale yellow coloured halogen (Symbol)8. Fe (4)9. The lightest element with no stable isotopes. (Symbol)11. Just 3 electrons (Symbol)13. Name for a charged atom or molecule. (3)14. Pretty lights. (4)15. Used to measure the mass of atomic and molecular particles (4, 12)18. The result of passing light through a prism (8)22. Element with four outer electrons (4)24. Calcium can look like this when heated (3)25. Number of s-electrons in sodium atom (4)26. Atomic number of Calcium (6)27. A red element (Symbol)28. Neon-22 is one of three (7)29. The rule for orbital occupation resulting in maximising electron spin (4)

Down:1. What type of charge is carried by a cation? (8)2. How many p-electrons does Be have (3) 3. A nucleon with a positive charge (6)7. If Na give a yellow flame test what does K give? (5)8. As you go across a period from L to R this increases (10, 6) 10. Which numbered shell has the lowest energy? (3)12. This nucleon has no electrical charge (7)16. A principal energy level (5)17. This is infinitesimally small, very elusive and negatively charged (8)19. Which element has electronic structure 2, 8, 2

(Symbol)20. Very, very small but extremely heavy (7)21. It has just one 6s electron (Symbol)23. Is the calcium ion singly or doubly charged? (6)

Got an hour? Take our:

Crossword challenge (30 mins); Chemistry Structure Search (15 mins)

and our ChemDoku (15 mins)

CCC

CCC

C

C

CCC

CCC C

C

O

O

O

O

OO

Cl Cl

Cl

Cl

HH

H

HH

H

HHHH

H

HO

O

O

O

O

O

C

CCC

CC

C C

Cl Cl

Cl

Cl

H

H

H

H

H

HH

HHO

O

O

H

HH

H

C

C

C

C

Connect the atoms in adjacent cells using single or multiple bonds to find the two molecules with formulae C8H6Cl2O3

Clue: both are constitutional isomers containing carboxylic acids and ether links.

Stru

ctur

e Se

arch

Solve our ChemDoku by filling in the squares with the periodic table elements such that no element is repeated in any row or column.

Unscramble the shaded elements to reveal two well-known scientists instrumental in understanding the structure of life.

ChemDoku

1

5

42

7

10 11

14

8

12

6

3

9

13

15 16 17

18 19

22 23

25

27

24

21

20

26

2928

Find the answers on our Facebook page @resonancenews17 Resonance Issue 7 || Autumn 2017

Funpage

Events Listings

ChemSoc Freshers Bar CrawlTickets available from ChemSoc.

21:00 September 28th

ChemSoc Book SaleDainton Foyer

LunchtimesWeek commencing October 2nd

Postgraduate Pizza SocialBloo88

18:30 October 5th

Endcliffe Village Charity EventOctober 7th

Resonance Issue 8 MeetingOctober TBC

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November TBC

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November TBC

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The team at Resonance would like to congratulate everyone who graduated over the summer.

In particular, we would like to thank the following students who have contributed to the past issue of Resonance and have graduated with

HEAR accreditation:

Helen ElmesAmelia Newman

Jing JingAbigail Sinclair

Resonance could not exist without their dedication and hard work over the past issues.

Various nights out, guest lectures

and non-alcoholic socials to be confirmed.

This Semester in Pictures

With contributions from: Ian Spooner, Grant Hill, Joshua Swift, Jo Buckley, Tim Manning and Joseph Clarke