Resonance Issue 7 | Autumn 2017

The University of ’s News Team

The Magical World of Chemistry

The Golden Age of Poison

The Hidden Detective Resonance The ’s Chemistry News Team

Resonance is a biannual newsletter produced by chemistry Editor Resonance Beth Crowston 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. Design Editor Joseph Clarke

Social Media Coordinator Editorial Helen Elmes Resonance is now well into its 3rd year of existence and this is its 7th issue. It may have had a Contributing Authors few facelifts over time, as new editors put their own stamp on it, but at its core it still encompasses all of Joseph Clarke its original values. Beth Crowston Jasmine Cotton When they created Resonance, Alex Stockham and Prof. Simon Jones Greg Coppack wanted to use it as a platform to encourage communication between Rachel Mowll people both inside and outside of the department. They wanted to bridge Zoe Smallwood the boundaries between peer groups and to engage people’s curiosity. As Matt Watson 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 t 5,000 miles away to be involved.

This new issue hosts a wealth of interesting articles as many new Copy Editors (and seasoned) contributors share their insights into stories from the department and the wider scientific community. Zoe Smallwood Joseph Clarke finally reveals where lecture theatres 2-5 have disappeared to in the Beth Crowston final installment of the history of the department (pages 5-6); Jasmine Dr Grant Hill Cotton assesses whether Harry Potter is a wizard or actually just a Dr Anthony J. H. M. Meijer budding (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 Email enthusiasm and support. He is the real protagonist in this story; [email protected] 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 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 Printers unique input into the legacy of Resonance. Print and Design Solutions Bolsover Street Happy reading. Sheffield S3 7NA Beth Crowston Contents On the Cover In This Issue Editorial 1

3 The Magical World of Chemistry 3

The Golden Age of Poison 4

The History of the Department 5-6

The Magical World of Chemistry Elemental Factfile: Iridium 6 Can chemistry explain some of the magical objects and spells of the Harry Potter universe? Science and Faith 7

An Interview with Charles Stirling 8

News from the Department 9-12

The Hidden Detective: 13-14 4 How Chemistry Catches Criminals Chocolate: Beneath the Wrapper 15-16

Chemistry Funpage 17

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

@sheffield.chem

13 The University of Sheffield Chemistry Alumni

@Resonance_Sheff

The Hidden Detective: [email protected] How Chemistry Helps Catch Criminals The chemistry of luminol can assist in the detection of blood. This and other scientific methods are employed to www catch criminals, even performed by Sherlock Holmes. http://bit.ly/2weV7M1

The University of Sheffield || Resonance Issue 7 2 Feature

The Magical World of Chemistry

By Jasmine Cotton

he wizarding world of Harry Potter has inspired a generation to read and appreciate Tliterature. However, personally I believe that the series also inspired a generation of budding . There are three main aspects in the wizarding world that and organic; most white inks contain titanium dioxide as can be explained by chemistry, these are: coloured fires, the pigment, other inorganic materials such as clays are flames and sparks; special inks; transformations. used as fillers or extenders. The closest Muggle example to the Marauder’s Map is invisible ink. Although invisible There are many mentions of coloured fires or flames in the upon writing, the ink can be visualised using chemical Harry Potter series: reactions, or physical changes. One of the most common invisible inks is lemon juice. This is not initially visible to “... dragons comprised entirely of green and gold sparks the naked eye, due to its composition of sugar, water, and were soaring up and down the corridors […] shocking- citric acid. However, once the paper with the lemon juice pink Catherine wheels five feet in diameter were whizzing applied to it is heated, the writing can become visible. This lethally through the air” is due to the citric acid. In paper, the cellulose fibres can be On the other hand, the fireworks created by mere Muggles degraded by citric acid – the glucose units in the cellulose can easily be explained. In fireworks, the colours are chains are broken down by hydrogen ions, leaving one side produced by heating metal salts that emit characteristic of the unit stable and the other able to bind with a water colours. For example, an orange coloured firework could . This is a cycle that repeatedly weakens the fibres be due to the presence of the metal salt calcium chloride. in the paper, allowing the paper to burn faster and with more ease. Thus, the section of paper with the lemon juice The metal salts emit their characteristic colours because applied will burn faster than the rest of the paper, and show the atoms of each element absorb energy and release it as the invisible ink message. light of specific colours. The amount of energy each atom absorbs is specific to each element, hence the light emitted The last example of the chemical links in Harry Potter are is specific to each element. Using the two equations: transformations: E=hν and c= νλ, (E is the energy, h is Plancks constant, ν is “Goyle’s potion exploded, showering the whole class. the frequency, c is the speed of light and λ is the wavelength) People shrieked as splashes of the Swelling Solution hit it is possible to work out the wavelength of light, and then them. Malfoy got a faceful and his nose began to swell like thus determine the colour of light that will be emitted. a balloon.” Ink chemistry appears many times during the Harry One of the most famous chemistry experiments is Potter series. One of the most famous appearances is the elephant’s toothpaste. The basic idea behind this is that Marauder’s Map, which only allows the user to see the concentrated hydrogen peroxide will break down rapidly, writing once it is activated with the correct words: due to the addition of a catalyst (potassium iodide, etc), into oxygen and water. The addition of soap to the reaction “He took out his wand, touched the parchment lightly, and will cause the creation of foam, as the soap reacts with the said, “I solemnly swear that I am up to no good”. At once, water. As the peroxide decomposition occurs, this creates thin ink lines began to spread like a spider’s web from the a high volume of oxygen that gushes out of the container. point that George’s wand had touched. [...] then words This oxygen pushes the foam out of the container, resulting began to blossom” in a large quantity of foam being released. 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 These are just three examples of the many in the Hogwarts view, ink is a colloidal system of fine pigment particles world which show that Harry Potter is really just a chemist dispersed in a solvent. Ink pigments are both inorganic in training, using simple chemistry reactions or principles.

3 Resonance Issue 7 || Autumn 2017 Feature The Golden Age of Poison By Jasmine Cotton

oison 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 Pbooks adopting it as the murder weapon. But do they depict it accurately? One of the great murder mystery authors was Agatha effect; the reduction in the solubility of an ionic precipitate Christie. Across more than 80 detective novels, she when a soluble compound containing one of the ions of the has killed off over 300 people, and at least 100 of those precipitate is added to the solution. This effect can be seen: were murdered using poison. Christie uses a vast range a solution of strychnine sulphate in water is completely of poisons in her detective novels, the chemistry behind clear, but after addition of potassium bromide, crystals of which is more often than not accurate in its description. strychnine bromide precipitate, see Figure 1.

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 Figure 1: Showing a solution of strychnine sulphate in water how other prescription medicines or household chemicals on the left, and the solution of strychnine after the addition of would react with these. This knowledge allows Christie to potassium bromide on the right. It is clear that crystals have spin a plausible plot, making her murder mystery books formed in the right hand beaker. Reproduced with permission ever more thrilling. from [4].

One book in which Christie’s chemical knowledge is applied Potassium bromide which was used was a common brilliantly, is her first-ever Poirot novel, “Mysterious Affair prescription medicine as well, one which the novel stated at Styles”, published in 1920. The basic plot line of this Mrs Inglethrop would occasionally take as a sleeping pill. novel is the wealthy Mrs Inglethrop is found dead in her Thus, the murderer had all of the necessary compounds to room one morning. The poison which kills her is found to hand already. be strychnine; a poison if given as a fatal dose, typically taking 15 minutes to act. This is the chemistry behind the murder of Mrs Inglethrop. Once potassium bromide was added to the tonic, a lethal During the time that “Mysterious Affair at Styles” was dose of strychnine would precipitate to the bottom of the written, strychnine was a common medicine. It was solution. As long as the solution was not shaken, the lethal prescribed as a remedy for heart and respiratory complaints. dose would be administered as Mrs Inglethrop reached the Thus, it was common to see in most households. In the end of the tonic. novel, strychnine was dissolved in water to make a tonic, one which Mrs Inglethrop took regularly. The question This is just one example of Christie exercising her therefore arises, how did she ingest a fatal amount of chemistry prowess. Clues of her chemical knowledge can strychnine? As mentioned above, lethal doses take around be found in her liberal poisons in other numerous novels. 15 minutes to act, so how was it that Mrs Inglethrop had Just a few examples include white phosphorus in “Dumb suddenly died one morning long after taking this particular Witness”; thallium in “The Pale Horse” and the infamous batch? Surely if this contained a lethal amount, then she cyanide in several novels. should have died much sooner. This is where Christie demonstrates her aptitude for chemistry. 1. http://bit.ly/2vuD3Mk 2. http://bit.ly/2uAdcE8 Through her studies to become a dispenser, Christie knew 3. http://bit.ly/2vROaQz that the addition of a large amount of potassium bromide to 4. Die tödliche Brechnuss. Strychnin – Von der Isolierung zur Totalsynthese, Klaus Roth, Chem. Unserer Zeit 2011, 45, 202–218. strychnine bromide tonic would lead to the precipitation of Chem. Unserer. Zeit. Copyright Wiley-VCH Verlag GmbH & Co. strychnine bromide cystals. This is due to the common ion KGaA. Reproduced with permission.

The University of Sheffield || Resonance Issue 7 4 Insight 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 see 1954 A Family Connection. ne of our own technicians, Stephen Atkin, has a family Oconnection 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 , who was never seen without a cigarette!

Photo 2: Undergraduate laboratories circa 1945 when the chemistry Photo 1: department was A floor plan of the chemistry department when it was still located in Firth originally located in Firth Court in the1940’s. Court.

Where were Lecture Theatres 2 - 5? ecture theatres 3 and 4 were located on D and E floor, Ldirectly above LT1, where 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. Photo 3: Two lecturers, attending a seminar at the time, noticed what Professor Wynne was going on and quickly scrambled out of their seats to (centre) and the extinguish the fire, thankfully before any major damage or female chemistry injury was caused! Lecture theatres 2 and 5 were located in team (1914-1918) the old East Wing, on A floor (which is now the bottom of responsible for the the Richard Roberts Auditorium) and D floor respectively, synthesis of the anaesthetic beta- and were removed when the building was refurbished to eucaine.1 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.

5 Resonance Issue 7 || Autumn 2017 Insight the Department the department. Everyone knows where lecture theatres exist, and where did they go? Mystery lecture theatres which dates back over 100 years. Zoe Smallwood how our department used to be. 2017 The Departmental Community. lthough the first female academic appointments would if they were in the company of a member of staff. The Anot take place until almost half a century later, during appointment of the department’s first female academic the First World War many female chemists were recruited was in 1995 (our very own Prof. Jane Grasby). Nowadays, to replace the men who were called up to serve. A team the department is the proud holder of an Athena Swan of Sheffield chemists were responsible for synthesising silver award for commitment to equality in science and the eucaine, a then-novel anaesthetic. The team’s contributions University Arms is open to all. often resulted in appointments as technical and teaching assistants once the war had ended.1 Staff numbers and their duties have also changed. In the 1970’s, there were approximately 70 technical staff, whose As the building has changed over the years, so has the duties used to include picking up items from stores that community itself. The department used to have segregated researchers had ordered. This number has declined over toilets for staff and students, postgraduates had their own the years to approximately 30 today, with the job of picking common room in the East Wing, and the University Arms up items from stores now handed over to researchers. was a place where students were only permitted to enter 1. http://bit.ly/2vRQqHt

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.

Elemental Factfile:By Beth Crowston Iridium ridium is a transition metal and is Although in its pure form it is white iridium has been found to be more Ia member of the platinum family. in colour, as part of a co-ordination abundant in meteorites such as the It has one of the highest densities of compound its colour can be tuned to Willamette Meteorite (4.7 ppm),1 it was all of the elements on the periodic span anywhere in the visible region of postulated that the crater was a product table (22.56 g cm-3) and is the most the electromagnetic spectrum. Hence, of an asteroid or comet impact. Due resistant to corrosion; being unaffected it is named after the latin word iris, to the age of the crater, scientists have by acids and bases alike. However, it meaning rainbow. formulated the Alvarez hypothesis2 is particularly brittle which makes it which posits that the mass extinction difficult to machine or form. To combat Pure iridium is incredibly rare, making of non-avian dinosaurs was caused by this, the metal is heated to a white heat up only 2 parts per billion of the Earth’s this particular meteor strike. of 1,200 to 1,500 degrees Celsius to crust. However, in 1980 a significant amount of iridium-rich clay was make it more amenable to work with. 1. http://bit.ly/2wFy10J Its primary use today is to harden found in a large buried crater with an 2. http://bit.ly/2xtc2Y3 platinum by making an alloy. estimated age of 66 million years. As The University of Sheffield || Resonance Issue 7 6 7

Opinion Resonance Issue 7 Science and Faith C H (more than double figure the in2001) themselves deemed who ‘irreligious’ to be was 25.7 % waned: 2011UKcensus, inthe percentage the of people Almost 400years later, influence the of religion has findingsthat rebuttedCatholic scripture. Inquisition’‘The campaignwider –a againstscientific threat of torture. This was merely one clash under and under placed house arrest after confessing under of Sun’s the rotation. was branded Galileo aheretic teachings – by claiming was centre the that Earth the around Sun). the This directly contradicted biblical of heliocentrism revolves (thattheory Earth the Two World Chief Systems”, he inwhich offered his Church for publishing “Dialogue Concerning the In was famously 1633,Galileo by Catholic tried the Religion and have science not traditionally mixed. press issue, this questioning how students the drew the world 6000-10’000years between ago. to Idecided years Bible old, the while claims created that God the Earth’s estimate geology that our planet is 4.54 billion scripture and clash. science For example, studies of the It however, was ceded, that there are some points where simply of design the an be omnipotent being. – evolution, Doppler the effect, respiration –could that scientific everything methods andwe observe exclusive at world the all: that we study through note, it was put to me that two the are not mutually world the behind we inwhich live ‘how? –the on other the hand, to explain seeks mechanisms the short, religion with ‘why? the deals incomprehensible teeming mass of humanity – in reasoning,a higher for a divine purpose a seemingly different questions. To manypeople, God represents student pointed out that are they to tools answer used were overwhelmingly insupport of one former; the When was this posited to students, the responses the conflictedpoint thethey to being irreconcilable?of work together, inany society to way? further Orare faith (and subdivisions) their all and coexist, indeed Head of State and Supreme Governor of Church the is directly to linked religion: IIis both Elizabeth Queen such as France, Australia and The China. UK, however, entirely countries secular (with no officialstate church) of England. that Considering fact the this, many can two the institutions of scientific study and entral to matter this is following the question: this have to remain true? two disciplines have separate; at even been war.the In though, does era themodern istorically

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A scientists as identify religious/people of utumn 2017 faith is noteworthy, given ’ questions. Science, 2 By Greg Coppack and there are 1 that most ’. Onthis 3. ttp://bit.ly/2uSgptI 2. 1. While statistics the show that commitment to asingle threat.”obvious in itself to replace and religion, which an seems is tolerance, while important, becoming is a belief need “The for complete open-mindedness and insightful answer: particularly one day become completely redundant, Ireceived a traditional religions was an indicator that may they recent the whether deterioration in popularity of system ages the between of 12and 14.Asking began to consider religion their as own their belief religiousfamilial background but agreed that they commitments. time with varying shared All a department religion practise who chemistry the same answers. students several I interviewed within fewer people may to look power ahigher for those answers to existential questions are provided, the religion is a result of advances as in science: more It that asserted could decline the be inorganised faith? to study and work maintaining while inscience one’s removed from as we science know it today. Is it possible unreservedly incontradiction.unreservedly are few occasions where and very science faith are large role to play. Ultimately, it said canthat be there it infavour of science, and undoubtedly it has a still it is not necessarily people because have abandoned organised religion may naturally diminish with time, should conflict. Furthermore,thewhilst role of people of faith no reason see why and science religion have you differently, believe the majority of rational among atheist and religious communities would It is plain that, afew loud, to see while fervent voices than considering what was more likely. instinctively and made sense sounded correct rather that each individual’s was comprised set belief of what scientifictheories. The answersseemed to indicate religious teachings) and proffered evidence the by in (regarding whatline believed between they major religions are rooted inancient history, faith is on decline, the answer this suggests that amore

Christianity inthe 1st) (I are Copyright Crown Extracts Survey © C h slam wasthought to founded inthe7thcentury, be rown Copyright 2006 Source: Nationalrown Copyright Statistics /Ordnance fluid system beginningbelief is to of usurp organisedusurp religion. 3 an erafar Interview

Anrof. Charles Interview Stirling FRS, has had a career with in chemistry Charles spanning many decades. Stirling He is a Fellow of the PRoyal 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. Charles’s interest in chemistry began His eventual position at Porton Down intramolecular interactions. Some of at age 12. He was fascinated by the allowed Charles a degree of free his best work has been conducted on burning metal of a magnesium strip, reign. However, his insistence not to strain in , multi-layering and the intensity of the light produced be involved in hurting people was on surfaces, and multiple low-energy encouraged him to learn more. problematic in a department based interactions. Surprisingly, as a young boy he was not around military research. Instead drawn in by the bangs of chemistry, but Charles worked on antidotes to nerve Charles has seen research in chemistry they would go on to play a role in his agents, which involved phosphorus change massively over the years, later career. chemistry, important to his future notably with computers and NMR research career. . He remembers using a He began his journey into the world of 16 MHz NMR spectrometer, which chemistry in Scotland, obtaining his when compared to today’s standard BSc from the University of St. Andrews, 400 MHz instruments, shows the before heading to King’s College amazing advancement that chemists London to study for his PhD. Here, he have achieved. He predicts that the next shared a lab with Sir , a big progression in chemistry will be a very influential scientist specialising in revolution in the synthesis of organic organic chemistry. biologically important molecules.

Soon after completing his PhD, But Charles has also witnessed the Charles was obliged to undertake change in academic culture. As a big national service. He looked around believer in equality, he felt that people enthusiastically for a non-barracks should be evaluated exclusively on job and found that one of his options their skills and is happy with the was a deferred job at the explosives changing landscape that has occurred department at Imperial Chemical After national service, Charles was over his life time with more female staff Industries (ICI). However, his troubled by the common question: in the department and across the whole impression was tainted when he met ‘do you go into academia or not?’ of academia. the company research director who Charles wanted to stay in research, had a patch over an eye and his arm in enjoying the unique life of a researcher. His passion for chemistry has often led a sling. This did not fill Charles with Happily, after his independenthim into performing outreach for both confidence and so his decision was research at Porton Down he felt that school pupils and the public, which “no”, but fortunately the government he had proved to himself that he includes the prestigious accolade of created a series of research fellowships was capable of researching without delivering the Royal Institute Christmas at several research stations around the a supervisor. Following a series of Television Lecture. On the back of country, including atomic research and positions around the country, in 1990, his outreach work he was awarded the Chemical Defence Establishment at he was offered a position at Sheffield, an Honorary Doctor of Science Porton Down. Charles was interviewed where he later became Head of research degree from the University of for his role by the novelist Harry Hoff Department. His research has focused Sheffield in 2007, for “raising the public (pen name William Cooper) who on physical organic chemistry, with understanding of science”. immediately took a shine to him. a particular emphasis on kinetics and Graduation Award for Charles More 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”.

The University of Sheffield || Resonance Issue 7 8 News News from the

By Zoe Smallwood Helen Sharman returns to Sheffield 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. Originally hailing from Sheffield, Helen completed her as part of her role in Mars Confectionary! She told the BSc Chemistry degree here in 1984, before working for the audience that she hadn’t thought about leaving, until she and later Mars Confectionary, heard the radio advert recruiting astronauts and decided working on Mars Ice Cream bars amongst other treats. to “go for it”. Helen encouraged the graduating class to Upon answering a radio advert stating “astronauts think beyond their qualifications and make the most of wanted- no previous experience needed”, Helen was any opportunities that may arise. She said: “there are areas selected from 13’000 other applicants to travel to the for us all to explore, if we remain open to learning, be space station as part of Project prepared to make the best of use Juno in 1991, which included of opportunity, and are confident a significant period of training to go for it.” in Star City, Moscow. Helen is now the Operations Manager Helen’s speech ended with her in the department of chemistry encouragement to take whatever at , opportunities come your way, and was interviewed on the 25th irrespective of whether it was on aniversary of her time in space your planned track or not. She as part of Issue 5 of Resonance in said: “my degree has shaped my 2016. life, but when I first graduated, I could not have known the Our very own Prof. Charles opportunities it would have Stirling was the orator for allowed me to explore.” She also Helen’s honorary degree in the revealed that , ceremony, and spoke about her one of the recipients of the 2016 many contributions to outreach who and the promotion of science paid a visit to the department a and technology, including a few months ago, was her personal book about space for children tutor during her studies! and being appointed as President of the Institute of Science After the ceremony, Helen took and Technology. Charles also the time to meet some of the discussed the significance of her “Whilst today marks the end Resonance team, and discussed degree, saying: “in these days what the department was like of cheap notoriety and shallow of an era of study for many of and what type of research the celebrity, Helen Sharman’s you, it is also the beginning of team were conducting. She also comments deserve attention… a new chapter in a world that told us how she had come into she has said “I would encourage a physical copy of Resonance everyone, aim high and have a go is full of opportunities.” containing our interview with at a new experience””. her, after a colleague had picked up a copy in Nanjing that had In her speech, Helen congratulated the new graduates, been taken out by Prof. Winter! 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 On behalf of Resonance we offer our congratulations to all world that is full of opportunities. A university qualification the new alumni of the department, as well as to our latest can be regarded as a proof of preparation; to use space award holders. We would also like to congratulate Helen terminology, it is a platform from which to launch into Sharman on receiving her honorary degree and thank her the future.” She spoke about her experiences of working for spending the time to talk to the team. in industry, including getting to taste chocolate every day For more information: http://bit.ly/2tP30XT

9 Resonance Issue 7 || Autumn 2017 News Department and Joseph Clarke Academic Awards 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).

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

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.

For more information: http://bit.ly/2u4tiAq For more information: http://bit.ly/2tP30XT http://bit.ly/2n9WuEE

The University of Sheffield || Resonance Issue 7 10 News The 1967 Nobel Prize: Fifty years later. “For their studies of extremely fast chemical reactions, effected by disturbing the equilibrium by means of very short pulses of energy”

In 1967 these words accompanied set out to study reaction kinetics by 1955 he expanded on the uses of flash the award of the Nobel Prize in using a flash lamp. The idea was to photolysis demonstrating its uses in Chemistry to , Ronald have a system set up in an equilibrium, organic and biological chemistry.4 George Wreyford Norrish and former which is then disturbed by an external Refinements to the method were made University of Sheffield professor, stimulus.3 over the years, most notably with the .1 discovery of the meaning shorter “Your flash photolysis pulses could be performed recording 2017 marks the 50th anniversary of method provides a picosecond timescales. this award, and is incidently the 15th powerful tool for anniversary of his death. The now The importance of their method Lord Porter moved to Sheffield in 1955 the study of various cannot be understated. Articulated where he remained until he moved to states of molecules perfectly by Nobel Prize presenter 2 the Royal Institute in 1966. and energy transfer Prof. H. Olander: “Detailed knowledge of the behaviour The Nobel Prize in Chemistry 1967 between them.” of activated molecules was meagre was awarded for the understanding and most unsatisfactory. Your Flash of chemical kinetics. Chemical Photolysis method provides a powerful reactions chiefly rely on the formation tool for the study of various states of of substances from reactants, but not molecules and the transfer of energy all reactions are equal. While some between them”. can be measured with a rudimentary clock, others proceed at velocities Fifty years have passed since George which currently defy measurement Porter and Ronald Norrish developed with all but the most sophisticated Flash Photolysis. In this time their technology. Take for example the method has been used countless process of electron transfer, which times to study kinetics and is still typically proceeds on the femtosecond in use today. The advent of new timescale, 10-15 s or one quadrillionth improved technology may have lead of a second. To put it into perspective, The process of flash lamp photolysis is to improvements in measurement a femtosecond can be said to form the as follows: a substance is placed next to speed and shorter timescale of study, same part of a second as a second is to the lamp, which provides the stimulus but it still required the innovation 31 688 764 years! required to excite the substance into an and vision of the first pioneering activated form or for molecules to be researchers. The story of flash photolysis began broken up. It is then possible to study 1. http://bit.ly/2vZ6jv2 in the 1940’s when Professor Norrish these molecules spectroscopically. By 2. http://bit.ly/2vguUIZ 3. http://bit.ly/2wzf8xb and his then associate George Porter the time George moved to Sheffield in 4. J. Chem. Educ. 52, 1975, 703 (http://bit.ly/2w4yGGr) Tom Roseveare awarded FHEA status 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. 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.

11 Resonance Issue 7 || Autumn 2017 News Kroto Day 2017

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. Kroto Day is an anuual outreach workshop in memory of The workshop involved PhD students Matt Watson and Beth the internationally renowned Nobel Prize winning chemist Crowston discussing the scientific scale. They encouraged and University of Sheffield Alumnus Prof. Sir Harry Kroto. students to think about the relative sizes of objects and This workshop welcomed over 30 year 7 pupils from how they all fit onto a single scale, from nanometres and Chaucer Academy to learn more about the research that Sir smaller, for the sizes of molecules and atoms, to gigametres Harry was awarded his Nobel Prize in Chemistry in 1996: and beyond, reaching the sizes of planets. the discovery of the , also known as buckyballs. The highlight of the workshop was for pupils to build their own buckyball using a specially provided kit. This hands- Buckminsterfullerene is an allotrope of , and stands on approach gave students the opportunity to visualise alongside the other traditional forms of carbon; and the symmetrical arrangement of carbon atoms in the . Buckyballs are formed from 60 carbon vertices buckyball. Both activities allowed students to learn more made entirely out of pentagonal and hexagonal faces and as about the interesting properties of the buckyballs and how its nickname suggests, is shaped like a traditional football. these properties relate to other carbon allotropes such In 2010 the breakthrough was named by fellow academics as graphite (layered carbon sheets used in pencils) and as one of the 10 most important discoveries made by their diamond. It also introduced concepts in and peers at UK universities in the past 60 years. chemistry, laying the foundations for future inspiration and enthusiasm in studying science.

Instagram Competition

2017 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 Left, winning postgraduate photo of DPQ crystals and right DPQ, a commonly synthesised compound in the group. winner of the undergraduate competition, crystals of ferrocene The compound acts as a building block ligand and in The undergraduate competition was won by Milan Nakum conjuction with metals such as ruthenium, it can be used who photographed the crystals formed from the synthesis to produce fluorescent cell-imaging agents or can be used of the organometallic sandwich compound ferrocene in therapeutic applications such as photodynamic therapy. (right photo). The synthesis of ferrocene is a second-year Derived from 1,10-phenanthroline, DPQ can be made undergraduate inorganic laboratory experiment. The using nitrating mixes like those used to make gun cotton reaction itself involves the reaction of cyclopentadiene or explosives. Despite having access to millions of pounds with iron trichloride. The crude product is purified worth of analytical equipment, you also know you’ve made using vacuum sublimation, which avoids the product it because it makes you sneeze! decomposing.

The University of Sheffield || Resonance Issue 7 12 Feature

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 excepturiT neque eget,he 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 adipiscingH maecenasidden 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.D Placerate magnat quis donec,ec ad pede eratt sed.ive: Malesuada ligula odio turpis hendrerit. Tristique sem potenti porttitor massa eget, leo metus Hsed id vel liberoow volutpat, at utC fusce nequehemis nulla lorem nullam. Massat odio rycras mi vivamus helps 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,ca euismod idt vestibulumch eget etiam C augue rhoncus,riminals 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, quamBy gravida Zoe felis malesuada Smallwood 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, rom Sherlock Holmes to the modern criminal sleuths of today, the entertainment world loves a good Fcrime 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?

ne of the most common scenes from forensics shows naturally secrete oils, which are transferred to surfaces Ois the detection of latent (i.e., invisible to the naked when we touch them. Depending on the surface they are eye) blood that someone may have tried to clean away. on, fingerprints can be enhanced or revealed by dusting First, the area needs to be treated with a visualiser to allow with fine powders that stick to the oils. Different surfaces any blood traces to show up. The visualiser reacts with require different types of powder, so a wide range exist for the blood and emits a glow which can then be seen and the correct scenes. But what if the surface is porous, like photographed (although the glow is much shorter-lived paper from a ransom note? This is where powders give way than depicted on screen). Where there is no blood the area to a compound called ninhydrin (figure 2). 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 Figure 2: Chemical ions used to activate it. This reaction releases energy as structure of ninhydrin. 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 Often dissolved in a volatile solvent such as ethanol or upon exposure to bleach, which may be a useful clue in acetone, ninhydrin is sprayed onto a surface and the itself if a clean-up operation has been performed at a crime solvent allowed to evaporate. When the hydroxyl groups scene before the detectives arrive. However, it can also in ninhydrin react with the terminal amine groups in damage DNA evidence before recovery, so only a small the amino acids and proteins in the fingerprint residue, area may be treated at first.1,2,3 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

Figure 1: Chemical structure of luminol.

nother key piece of evidence in a forensic trail is Afingerprints. 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 Figure 3: Dimeric product from the reaction of ninhydrin with a bit more work to be visualised and recorded. Our fingers protein and amino acids in fingerprint residues.

13 Resonance Issue 7 || Autumn 2017 Feature

efore the development of the state-of-the-art analytical Although the improved test came too late to convict the Binstrumentation that we use today, the field of forensic killer, the Marsh Test (as it came to be known) became a science had to cope with cruder methods. In the 1800’s, common test for arsenic poisoning and arsenic trioxide’s 5 arsenic trioxide, As2O3, was considered an effective and status as a near-perfect poison came to an end. almost undetectable method of poisoning someone. The compound was odourless and poisoning gave symptoms ne of the most famous forensic scientists of all time similar to cholera, a common disease at the time. These Ois suprisingly Sir Arthur Conan Doyle’s character properties meant the compound became known as Sherlock Holmes. Despite being a fictional character ‘inheritance powder’ due to its use to dispose of spouses in stories published in the 19th century, some of the and family members! This was until a London chemist science and forensic work that Holmes conducts in his by the name of John Marsh was asked to investigate a cases was not too far from the cutting-edge forensics of case suspected to involve arsenic poisoning. Marsh used the time. It raised awareness of the application of science

hydrogen sulphide, H2S, to detect the presence of arsenic. and chemistry to catching perpetrators and exonerating Unfortunately, by the time the trial came around the test innocent parties. For example, his first use of fingerprint results had decomposed, resulting in the jury declaring the analysis was in 1890, 21 years before Scotland Yard began defendant innocent. Sometime afterwards, the defendant using the technique!6 To commemorate his contribution confessed to the killing, which motivated Marsh to improve to chemistry, the Royal Society of Chemistry presented his test so the same mistakes would not happen again. He him with an honorary fellowship; the first (and currently constructed a setup which involved reacting a sample of only) fictional character to receive one. Although Holmes body tissue with zinc and acid. was obviously not able to receive his medal in person, the award was presented by none other than a Northern Irish As O + 6H SO + 6Zn → 2AsH + 6ZnSO + 3H O 2 3 2 4 3 4 2 chemist by the name of Dr John Watson.7 Equation 1. Synthesis of arsine gas (AsH3) from As2O3. 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 Poisoned tissue would produce arsine gas, AsH3, which faucibus faucibus at. Leo ipsum magna vestibulum, senectus non ut, dui massa a sed ipsum ac suscipit, integer iaculis vestibulum ante rutrum pellentesque,1. sedh ttp://bit.ly/2vSvjF2accumsan eu molestie. Sed varius pretium, mauris could be ignited to leave behind a stable black residue that adipiscing dapibus venenatis nullam. Rhoncus 2.class excepturihttp://bit.ly/2wUkb7e neque eget, amet neque laoreet sagittis lorem consequat, lacus adipiscing sed. Viverra nam cras in diam, amet ante ipsam magna, aliquam id sit fusce would not decompose over time. lorem magna enim, velit nisl curabitur lectus 3.sit diamh ttp://bit.ly/2uAcGpuneque, ligula libero donec ipsum ut pellentesque duis. Lacus viverra rutrum turpis sed, lacus amet4. portah montesttp://bit.ly/2uAeQpi mauris volutpat eu, class vel. Nullam ipsum 2AsH → 3H + 2As sit, suspendisse neque urna augue lacus id. Enim id. Libero at. Porta dui consectetuer, nunc metus, lectus 3 2 molestias dolor, ornare id sagittis, hendrerit posuere5. mih prointtp://bit.ly/2wGMBCr eleifend placerat. Sit vel, quam nonummy nibh lorem litora, pellentesque lectus vestibulum eleifend6. nequehttp://bit.ly/2uDa6ea quam facilisis. Equation 2. The combustion of AsH3. Et risus consectetuer adipiscing maecenas vitae7. arcu,http://bbc.in/2vS4PmS 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,

The University of Sheffield || Resonance Issue 7 14 Research Chocolate: Beneath the Wrapper By Rachel Mowll

t some point during our time studying science, most of us will learn a little about the chemistry of Achocolate. 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 of chocolate. Its purpose is to ensure compounds present in chocolate surprisingly complex and teaching is that the fat molecules from the which have been linked to this often focussed on the manufacturing cocoa butter solidify in the correct feel-good effect. However, is there process, including the all-important polymorph to give chocolate with the any evidence for it or is it just wild process of tempering. Anyone who has correct melting temperature. speculation? Most of these claims watched the The Great British Bake are centred on molecules involved in Off will be familiar with this technique Chocolate has long been known the production and/or regulation of on a small scale, and as chemists we to make us feel good and is the neurotransmitters serotonin and know that it is also performed on an even considered by some to be dopamine in the brain, both of which industrial scale in the manufacture an aphrodisiac. There are a few 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 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.

15 Resonance Issue 7 || Autumn 2017 Research

One psychological effect chocolate is from the name of the Cacao Tree from chocolate for this to be dangerous. known to have is as a stimulant. It is which cacao beans are harvested, However this is not the case for dogs well known that it contains caffeine, Theobroma Cacao. Incidentally,with the theobromine in chocolate with 100 g of chocolate containing an Theobroma literally means ‘food of causing nasty symptoms such as amount comparable to a cup of tea. the gods’. Theobromine is structurally nausea and vomiting, diarrhoea, And while caffeine may not exactly similar to caffeine, with just one seizures, heart attacks and even death. make you happy it may provide a methyl group removed. boost to those in need of energy. As should be becoming obvious, it’s Theobromine is also responsible for unlikely that there’s one psychoactive Chocolate also contains a related another property of chocolate, its compound in chocolate that makes it but less well-known stimulant, toxicity in dogs. While it is also toxic so popular. It is probably more to do theobromine. As a chemist it is easy to to humans in high enough doses, it with the high sugar and fat content, assume that this compound contains would be near impossible for even as well as the distinctive flavours and bromine, but the name actually comes a real chocoholic to eat enough smooth, creamy textures.

66% of chocolate is eaten The Ivory Coast between meals with 22% eaten is the largest single producer of between 8pm and midnight. the world’s cocoa.

White chocolate is not technically 1842, the year Cadbury chocolate due to the absence of created the first chocolate bar. cocoa solids and chocolate liquor.

1875, the year Daniel Peter from Switzerland created Nearly 70% of the world’s milk chocolate. cocoa supply comes from Africa.

he flavour of chocolate comes As for the fats, the fatty acid molecules melting point of 33.8 oC. This means Tfrom the cacao bean. Returning found in chocolate come from cocoa it will melt in the mouth but not when to the manufacturing process, cacao butter and are palmitic acid, stearic stored at room temperature. beans are fermented and proteins in acid and oleic acid. The first two are the beans are broken down to amino saturated fatty acids while oleic acid Of course, commercial chocolate acids. Then the beans are roasted, is unsaturated, giving it a kinked does contain additives. For example, during which time some unpleasantly structure which affects the packing of vanillin, the compound responsible for flavoured volatile compoundsmolecules and therefore the melting giving vanilla its flavour, is commonly evaporate and a cascade of reactions point of the chocolate. For this reason used. It is anecdotally reported that occurs between the amino acids the proportions of the fatty acids are American chocolate tastes sour, and sugars. These reactions produce varied by manufacturers to give an or even ‘like sick’! Interestingly, a range of molecules including optimum melting temperature. The American brands often use butyric aldehydes, esters, ketones and furans previously mentioned six different acid as an additive to give chocolate which give flavour and colour. polymorphs of cocoa butter have a sour note. So that mystery may be different melting temperatures,solved. with form V being preferable with a

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 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.

Chocolate Facts: Article References: http://bit.ly/2uCPe72 http://bit.ly/2uDf8HE http://bit.ly/2w0WVZ8 http://bit.ly/2hVmuo5 http://bit.ly/2uSsoaP http://bit.ly/2w14m2z http://rsc.li/2vRRECD http://bit.ly/2fBHWxP

The University of Sheffield || Resonance Issue 7 16 Funpage Chemistry Funpage

Across: 1 2 3 4 Down:

3. A dumb-bell shaped space in 5 6 1. What type of charge is which to find an electron (1,7) carried by a cation? (8) 8 4. In the iron atom, in which 7 2. How many p-electrons numbered shell are the outer 9 does Be have (3) s-electrons (4) 3. A nucleon with a 10 11 12 5. Not so much a bore, more an positive charge (6) enlightened scientist (4) 13 14 7. If Na give a yellow 6. A pale yellow coloured flame test what does K halogen (Symbol) give? (5) 8. Fe (4) 8. As you go across a 9. The lightest element with no 15 16 17 period from L to R this stable isotopes. (Symbol) increases (10, 6) 11. Just 3 electrons (Symbol) 10. Which numbered 13. Name for a charged atom or 18 19 shell has the lowest molecule. (3) 20 energy? (3) 14. Pretty lights. (4) 12. This nucleon has no 15. Used to measure the mass of 21 22 23 electrical charge (7) atomic and molecular particles 24 16. A principal energy (4, 12) level (5) 25 18. The result of passing light 17. This is infinitesimally through a prism (8) 26 27 small, very elusive and 22. Element with four outer negatively charged (8) electrons (4) 19. Which element has 24. Calcium can look like this 28 29 electronic structure 2, 8, 2 when heated (3) Got an hour? (Symbol) 25. Number of s-electrons in sodium atom (4) 20. Very, very small but extremely heavy 26. Atomic number of Calcium (6) Take our: (7) 27. A red element (Symbol) 21. It has just one 6s electron (Symbol) 28. Neon-22 is one of three (7) Crossword challenge (30 mins); Chemistry Structure Search (15 mins) 23. Is the calcium ion singly or doubly 29. The rule for orbital occupation resulting in charged? (6) maximising electron spin (4) and our ChemDoku (15 mins) ChemDoku Cl Cl O C O H H O H C C H C C O C C H O H C C C C H C O H H C H C O Cl Cl H H C C H C H O O O H Cl Cl H C O C CCC O H O H H C C H H

Structure Search Structure ClC Cl H O H C C H H C O Solve our ChemDoku by filling in the squares with the periodic Connect the atoms in adjacent cells using single table elements such that no element is repeated in any row or or multiple bonds to find the two molecules with column. formulae C8H6Cl2O3 Unscramble the shaded elements to reveal two well-known Clue: both are constitutional isomers containing scientists instrumental in understanding the structure of life. carboxylic acids and ether links.

17 Resonance Issue 7 || Autumn 2017 Find the answers on our Facebook page @resonancenews Events Listings ResonanceNEEDS YOU! ChemSoc Freshers Bar Crawl Tickets available from ChemSoc. Interested in writing for us? 21:00 September 28th

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We would love for you to get involved in our next Postgraduate Pizza Social issue! We welcome anyone who is interested in writing Bloo88 18:30 October 5th or researching articles, designing or contributing to our social media presence, regardless of experience or Endcliffe Village Charity Event October 7th year of study. As a bonus, contributing to Resonance is HEAR accredited. Resonance Issue 8 Meeting October TBC If you are interested email the team at: [email protected] Annual ChemSoc Fireworks Don’t forget to follow us on Social Media to keep Lecture November TBC updated. Cambridge NanoAmbassador Talk November TBC

Nanjing Karaoke Social: Welcome our new Nanjing Students TBC 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 Various nights out, contributed to the past issue of Resonance and have graduated with guest lectures HEAR accreditation: and non-alcoholic socials to be confirmed. Helen Elmes Amelia Newman Jing Jing More details can be found at: Abigail Sinclair www.sheffield.ac.uk/chemistry/ Resonance could not exist without their dedication and hard work over news/events the past issues. @SheffieldChemSoc on facebook This Semester in Pictures

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