JEWEL PURPOSE DISCOVER HOW SYNTHETIC DIAMONDS ARE …€¦ · Branded Content, Tower House, Fairfax...

Issue 2 // Summer 2014bristol.ac.uk/chemistry

JEWEL PURPOSE DISCOVER HOW SYNTHETIC DIAMONDS ARE CHANGING SCIENCE

HOPS & BEER: THE CHEMISTRY BEHIND THE SIMPLE PINTJAKE MACMILLAN: REMEMBERING A SCIENCE GREAT

02 Chemistry Explored // Issue 2

WelcomeWelcome to the second issue of Chemistry Explored. We’ve been delighted with the feedback from our first issue, so much so that we’ve decided to increase

the pagination so we can bring you more news and features about the people and the work that makes Bristol such a great place to be.

You’ll read about scientists sharing their enthusiasm for nanoscience and electrochemistry over a pint; a herbal walking tour with a chemistry focus; our prize-winning students; a retrospective on a science great and former colleague; what our porters really think; and a great deal more besides.

As I write these words, we’re approaching the end of another successful academic year. Well done to all our undergraduates who completed their exams, good luck to all those graduating this year, congratulations to postgraduates who’ve won prizes at conferences, and to staff who’ve won prestigious awards for their research.

With Open Day seeing thousands of hopeful students visit, we look forward to welcoming even more people into our school.

Professor Nick NormanHead of the School of Chemistry

NewsPint of Science 03Off to Princeton, Chemistry on film 04Bristol herb tour 05Skirting Science 06We love Bristol 07

FeaturesThe late, great Jake MacMillan 08Diamonds are forever 10 The chemistry of hops and beer 12 Meet the porter 14 Chemistry in numbers 15Life through a lens 16

University of Bristol School of ChemistryCantock’s Close, Bristol BS8 1TS, UK Tel +44 (0)117 928 8201 Web bris.ac.uk/chemistry

Email [email protected]

Editor Aliya MughalTo find out more about our courses and programmes, visit: bris.ac.uk/study

Chemistry Explored is produced in association with Immediate Media Branded Content, Tower House, Fairfax Street, Bristol BS1 3BN Tel +44 (0)117 927 9009 Web immediatecontent.co.uk

Group Editor Dan Linstead Group Art Editor Will Slater Director, Branded Content Julie Williams With thanks to Caroline Goode, Daniela Plana, Becky Brooks, Megan Shaw, Rose Silvester, Tom Simpson, Rebecca Ingle, Lexy Miles-Hobbs, Jenny Slaughter, Natalie Fey, Peter Crowther, Steph HarrisPhotography Bhagesh Sachania

Unless otherwise indicated, copyright in this publication belongs to the University of Bristol. Views expressed in Chemistry Explored do not necessarily reflect those of the University. The Editor reserves the right to edit contributions received. While care is taken to ensure accuracy of information, this cannot be guaranteed. Printed in the UK by William Gibbons.

Also in this issue…

UPDATE

Chemistry Explored // Issue 2 03

updateThe latest news from the School of Chemistry

HOW can scientists engage more people in their research? By taking it to the pub! That’s the solution which has proven successful in London, Cambridge, Oxford and now Bristol during a sell-out tour of the country’s finest watering holes.

No more is the seemingly alien world of science the sole preserve of university researchers, thanks to the Pint of Science festival, which saw several of our academics take their work into an alternative environment. The resulting discussions led to some novel suggestions for how science could be applied to the everyday world.

Tickets for the Bristol events sold out before the doors even opened, with a curious crowd eager to learn about everything from nanotechnology to energy, to the brain and volcanoes. The School of Chemistry was well represented in the ‘Chemistry and Physics’ themed evenings held at Channings in Clifton.

On the first night Dr Rob Harniman and his PhD supervisor Professor Mervyn Miles talked about their efforts to “touch the nanoworld”. Their simple, yet thorough explanations of the different microscopy techniques developed at Bristol University and around the world led to some inspired discussions between scientists and non-scientists alike about the possibilities for microelectronics and medical diagnosis.

Professor David Fermin and his final year PhD student David Parker talked about “the electrochemist dream” – championing renewable energies, particularly solar, and the need to develop new photovoltaic materials that provide cheap, efficient alternatives. Both were grilled by pub-goers on the green credentials of such technologies and calls to develop a complete, systematic approach to energy.

The festival was hugely successful in

helping the University and Bristol’s wider community relate to each other – here’s to a rerun next year.

Find out what inspired Daniela, now a Chemistry mentor, to take up science: http://tinyurl.com/ncbcuec

From bench side to bar table

Pint of Science brings the best

academic scientists in the UK to local pubs so

that they can explain their latest research

What is Pint of Science?Pint of Science sees some of the world’s leading experts from six countries and 21 cities travelling to pubs across the globe to discuss their latest findings with the public.

Find out more at: pintofscience.com

Daniela Plana and Becky Brooks on how scientists are taking their subject to the pub


You can take a look inside the School of Chemistry in a series of new videos in which staff and students show what’s on offer in some of the UK’s best teaching laboratories. The School offers up world-class lecturers and boasts an active student society which helps undergraduates develop the confidence and skills for life after university.

n Chemistry in 60 seconds – Head of School Nick Norman reveals how he went from being a Bristol undergraduate to Professor of Inorganic Chemistry

n Student views – hear what current students have to say about their time at Bristol

n The student experience – explore the School of Chemistry labs, lecture theatres, library and social spaces

bristol.ac.uk/chemistry/courses/undergraduate/videos/

INTERNATIONAL AWARDS, recognition from one of the UK’s leading agrochemical centres, and a prize-winning talk - that’s all before Megan Shaw completes her PhD at the Bristol Chemical Synthesis Centre for Doctoral Training.

Megan’s research in the Bower research group sees her working with agri-business Syngenta, developing catalytic methods for the construction of novel types of complex molecules which are of interest to both the pharmaceutical and agrochemical industries.

In 2013, she took the Synfacts poster prize at the 17th IUPAC International Symposium on Organometallic Chemistry Directed Towards Organic Synthesis in Colorado, followed by first prize for her poster presentation at the Syngenta Chemistry Collaborative Research Conference back at Jealott’s Hill. In May 2014 Megan won first prize for her talk at the Third Year PhD Research Symposium.

“My PhD gave me the opportunity to choose a research project I was interested in, and my experience at Bristol has increased my desire to continue working in academia,” says Megan, who in 2015 will head to Princeton University to become a postdoctoral researcher.

PHD STUDENT HEADS TO PRINCETON

UPDATE

Chemistry on film

UPDATE

Chemistry Explored // Issue1 05

One of the many wonderful things about science is the new perspectives it can provide, especially when combined with another area of expertise.

Staff, students and friends of the School of Chemistry recently discovered this for themselves during a mini herbal tour of the city.

Bristol-based medical herbalist Max Drake led the group of curious chemists from the doorstep of Cantock’s Close, home to the main Chemistry building, on through some of the city’s most notable hotspots, exploring some of the herbal and medicinal plants that are a constant source of inspiration for science.

From the cultivated varieties in the raised bed at the entrance to Chemistry, to the common wild plants found on Brandon Hill, to the impressive herb garden just below Cabot Tower, Max gave the group an education in how the flora and fauna we admire for their superficial qualities have infinitely more to teach us.

As well as showing the group more than 30 different plants and telling them about their uses and some of the known active compounds involved, Max discussed making tinctures and teas and how to dry herbs. He talked about the relative merits of wild and cultivated varieties, how the chemical understanding of plant remedies often lags behind their successful use, and the economics of gathering wild plants versus buying herbs already picked and dried.

Max, who runs the nearby Urban Fringe Dispensary, was an excellent guide and showed how the School of Chemistry’s location gives us easy access to so many fascinating plants and places. Read more about the herb walk on the Picture It… Chemistry blog: chempics.wordpress.com/2014/07/02/herb-walk/

Bristol’s herb tourRose Silvester goes on a tour of the city’s herb hotspots


Cabot Tower

School of Chemistry

University of Bristol

Brandon Hill

Park Row

B4051

Cantock’sCloseA4018

Jacob’s Wells Rd

Park St

Hill StCharlotte St

Charlo

tte S

t

Great G

eorge S

t

Bridgewood Ln

College Green

Park St

Berke

ley S

q

Berke

ley P

l

Upper

Byron Pl

Queen

’s Para

de

BrandonSteep

Col

lege

St

St G

eorg

e Rd

Frog Ln

Park St

Open University students visit BristolOpen University students from as far afield as Malaysia joined Chemistry’s teaching laboratories over the summer as part of a three-day residential course.

In total 73 students from across the world including the UK and Europe, all in their second year of study, took part in experiments investigating the redox

chemistry of tin, using UV-Vis spectroscopy to calculate the number of ligands on copper complexes, synthesising amides and honing their titration skills.

On the final day, the students got to put their newfound practical skills to the test making and using a Grignard reagent for an organic synthesis.

The Route1 Flower bed at corner of Cantock’s Close and Woodland Road:wild opium lettuce, verbascum,achillea, verbena bonariensis

2 Entrance to Brandon Hill Park from Berkeley Square:dandelion, herb robert, plantains: broadleaf, narrowleaf or ribwort

3 Herb bed just below Cabot Tower:feverfew, borage, lemon balm, comfrey, camomile, sage, mint, lavender, fennel, angelica, nigella, rosemary, thyme, nepeta, tansy, hypericum

4 Junction of several paths below the Tower and ponds:lime flowers on lime tree

5 Wild area at the bottom of the hill:oxeye daisy, geranium, red clover

Medical herbalist Max Drake (left) practices in Bristol at the Urban Fringe Dispensary in Colston Street

1

23

4

5


UPDATE

IT’S A COMMON MISCONCEPTION among young teenage girls that a career in chemistry is all about wearing a lab coat. They are often unaware of the broad range of careers that chemistry can lead to. Skirting Science has been inspiring 14 to 17-year-old girls since 2009, showing them the many different opportunities that a career in science can lead to.

I’m about to go into my fourth and final year of my studies and this summer I joined the Picture It… team to help them develop outreach workshops for this year’s Skirting Science event at Broadoak College, Weston-super-Mare.

We worked with three groups of 10 students in our workshop and, using an interactive talk, we introduced the girls to chemistry in five different industries

– pharmaceuticals, dyes, food, cleaning products and perfume.

In the first part of the workshop we observed how the smell and solubility of benzaldehyde and vanillin varied as a result of their structures, we demonstrated smells by spray tests and the students carried out a solubility experiment.

Applying the knowledge from the first half of the workshop, students discussed how structure relates to the properties of molecules and selected likely candidate molecules for the different industries.

It was really rewarding to share the students’ enthusiasm. It was clear from the feedback that allowing the students to make a link between science and everyday life helped to bring the topics into context.

Third year undergraduate student Lexy Miles-Hobbs describes her experience of developing outreach projects for the national Skirting Science event, aimed at encouraging more female school students to explore the scientific life

For the pharmaceutical industry, the students were asked to look for candidate molecules which were soluble, containing a non-polar segment to cross the cell membrane but also a polar segment, so that the drug reaches systemic circulation and has a biological effect. They were also told that sometimes reduced side effects can be achieved by making the molecule more polar so that it can be excreted. The girls chose two likely candidates – can you identify which of the following fulfil the required properties?

Take the challenge

Turn to page 13 for the answer, and for the latest entry from Picture It…

Skirting Science – getting girls into chemistry

Skirting Science is an award-winning event that inspires

the next generation of female scientists

Molecule A Molecule B


WE BRISTOLWhat the Chemistry hopefuls are saying about Bristol University…

UPDATE

EVERY YEAR, the University of Bristol welcomes thousands of students and their parents to a series of Open Days that give them a chance to see the places and people they could meet as a Bristol student. This summer, we asked a few Chemistry hopefuls what inspired them to check out Bristol.

We want to hear from you! If you’ve anything you want to tell us about your experiences at Bristol University, or if you have any thoughts about Chemistry Explored, then please email us at [email protected]. YOUR SAY

Charlotte McDermot“I’m interested in Biochemistry and Chemistry. I didn’t really know what to expect from the Open Day but I’m very impressed with the staff, students and facilities. I’m definitely going home with a very positive impression of Bristol.”

Amy Williams“Bristol is a top university. The labs were very impressive and the talks were very informative. Bristol is very spread out and not too built up, which is nice. It doesn’t feel like a city.”

Shiqing Zhou “The Chemistry labs are really impressive. Bristol is a very good city. I really like the environment – it’s a really green city.”

Chantelle Foster “Bristol is a top research university. It’s a lovely city, green and modern. I especially enjoyed the view from the top of the Chemistry building! The course attracted me as in the first year you can do a third of modules from other sciences such as physics and maths.”

Laurence Alexander “The main things that have impressed me are the state-of-the-art labs and the greenness of Bristol itself.”

Daniel Morgan“The course looked really good so I wanted to come here and check out the university and facilities.It’s a lovely location. I like the fact that it isn’t campus-based like some other universities.”

SCIENTIFIC LIVES


Tom Simpson remembers a towering figure in chemistry and plant physiology

P rofessor Jake MacMillan FRS (1924–2014), although an organic chemist first and foremost, was one

of the United Kingdom’s most brilliant interdisciplinary scientists. A young PhD student joining his group even in 1969 would have rubbed shoulders with fungal geneticists, plant physiologists and enzymologists as well as being exposed to internationally leading natural product chemistry, advanced organic synthesis and mechanistic work and state-of-the-art analytical methods including GC-MS.

Jake was born and brought up in Lanarkshire, Scotland and was the first in his working class family to go to university. He gained his BSc and PhD at Glasgow University and, always a

passionate and gifted footballer, played for the then Scottish First Division team Third Lanark as an amateur, turning down offers of professional football contracts in favour of a career in science.

His first publication from his PhD studies with JD Loudon in Glasgow was on the identification of the 7-membered ring in the famous plant alkaloid, colchicine, isolated from the autumn crocus and used widely for the treatment of gout.

In 1948 Jake joined the Frythe laboratory of ICI as part of a small but high-powered group of organic chemists and microbiologists whose goal was to isolate novel biologically active metabolites from fungi. An almost immediate fruit of this work was the isolation from Penicillium

Professor Jake MacMillan (here pictured with his wife Anne) had a distinguished career which saw him achieve the highest honours in chemistry

The late, great Jake MacMillan

a tribute to a pioneer of synthetic biology

Distinctions1973 President of the International Plant Growth Substance Association

1978 Elected Fellow of the Royal Society

1978 Elected Corresponding Member of the American Society of Plant Physiology

1978 Flintoff Medal, Royal Society of Chemistry

1982 Research Medal, International Plant Growth

1987 Elected Distinguished Foreign Scholar of Mid-America Association of State Universities

1987 Elected Honorary Member of the Japanese Society for Chemical Regulation in Plants

1988 Royal Society of Chemistry Hugo-Muller Lectureship and Medal

1988 Royal Society of Chemistry Award in Natural Product Chemistry

1988 American Society of Plant Physiology, Charles Reid Barnes Award

1989 Elected Honorary Member of the Botanical Society of America

1990 Wilson Baker Lecturer, University of Bristol

1991 Foreign Associate of the US National Academy of Sciences

1995 Pergamon Phytochemical Prize


Jake MacMillan and gibberellins

In the 1960s the gibberellins (GAs) research of Jake MacMillan came to prominence. MacMillan was the international authority on the physiology and chemistry of the agriculturally important family of plant hormones, the gibberellins, and his contributions led the field for nearly four decades. He collaborated vigorously with botanists and horticulturalists throughout the world and he has profoundly influenced research on the study of growth control in higher plants.

MacMillan also participated in determining the molecular structure of the GAs and developed gas chromatography-mass spectrometry (GC-MS) methods to identify low abundance GAs in plant tissue. This led to the elucidation of the GA-metabolic pathway, both in the fungus, Gibberella fujikuroi, and intact seeds, enzyme preparations from seeds and vegetative shoots of higher plants.

There are now more than 125 GAs known in plants (many isolated and characterised in Bristol by MacMillan and his many international collaborators). Gibberellic acid and synthetic derivatives have gone on to be used extensively in agriculture and horticulture. They reverse dwarf phenotypes in plants such as maize and have found widespread use as an initiator of the germination of barley in the malting process, increasing flowering, and in the grape-growing industry to induce the production of much bigger bunches of grapes.

The influence of biological chemistry in Bristol was given impetus by the return of Tom Simpson (1990-present). His research has focused on natural products and underpinning biosynthetic pathways, particularly the enzymatic processes and genetic control of polyketide biosynthesis.

The late professor was a world-renowned expert on plant growth hormones

griseofulvum of the fungistatic agent griseofulvin since widely used for treatment of dematophytic infections. The young Scot had the temerity to tell Nobel Prize winner Sir Robert Robinson, at the time a consultant for ICI, that his suggestions for the structure were wrong and on drawing his own proposed structure on the blackboard, Sir Robert immediately jumped up and declared, “Problem solved!”

Jake then isolated the first of a group of compounds that were to become his lifelong major interest – the gibberellins, compounds produced in minute quantities in higher plants which are essential for their normal growth and development.

In 1963, Jake came to the University of Bristol where he initiated a programme of work on fungal metabolites which remains a mainstay of the Chemistry faculty to this day. The excellence and impact of Jake’s work resulted in his election as a Fellow of the Royal Society (FRS) in 1978 and the rare distinction of Foreign Associate of the US National Academy of Sciences in 1991. He received many other national and international awards, notably the Flintoff Medal of the RSC in 1978, and both the RSC Hugo-Muller Lectureship and Award for Natural Product Chemistry in 1988.

Jake retired from the School of Chemistry in 1990 after seven years as Head of Organic Chemistry to take up a senior research fellowship at Long Ashton Research Station. He returned to Chemistry as a Senior Fellow in 2003. Jake was always a gentle but incredibly inspirational man. He is renowned for his many pithy comments, not least the MacMillan formula for success being the product of IQ and AQ, the latter being politely defined as application quotient.

Jake MacMillan will be commemorated through the establishment of the MacMillan Postgraduate Prize in Organic and Biological Chemistry.

Above: Bristol’s Mass Spectrometry laboratory

INNOVATION


Rebecca Ingle meets Professor Paul May to look at the ways in which synthetic diamonds are revolutionising science

foreverW hen you think of diamonds, you

probably think of expensive jewellery, maybe even drill

bits or saws. You probably don’t think of quantum computing, laser optics, solar cells and even brain-computer interfaces. For Professor Paul May, these are just some of the exciting applications of what might seem to most like an inert, expensive rock.

The idea for the Bristol Diamond Group came from Professor Martin Lowson in 1991, an aeronautical engineer with a dream of being able to harness the hard-

wearing properties of diamond for use in aircraft parts. However, it quickly became apparent that, whilst people could successfully create synthetic diamonds, at that time no one really understood how they grew, much less how to control the growth process for such applications.

Professor Lowson contacted an

expert in gas-phase chemistry, Professor Mike Ashfold in the School of Chemistry, to help set up a new joint research project to make and study diamond films. Professor May had just finished his

PhD at Bristol in plasma processing of semiconductors, and so was in the right place at the right time, with the right background, to join the new diamond

Professor Paul May of the University of Bristol

DIAMONDS ARE

1893 After discovering tiny ‘diamonds’ in a meteorite crater in Arizona, Dr Henri Moissan creates the diamond simulant, Moissanite.


Molecules That Amaze Us

When not working on scientific problems that sound like something out of a sci-fi film, Professor Paul May has been working hard on his new book, Molecules That Amaze Us. Each chapter will feature a different molecule, with information on its chemistry and importance, written in an accessible and engaging style. The format of the book will be familiar to fans of Professor May’s ‘Molecule of the Month’ webpage (www.chm.bris.ac.uk/motm/motm.htm) but the book will feature additional content, cartoons and plenty of historical anecdotes.

Molecules That Amaze Us is due for publication in a few months, just in time to be a perfect Christmas gift for all those chemists you know and love.

group as its first postdoctoral researcher.

Twenty-three years later he now runs the diamond lab with Professor Ashfold and Dr Neil Fox from the School of Physics. The lab is now the only chemistry-based synthetic diamond lab in the United Kingdom.

One of Professor May’s primary interests has been in understanding the fundamental chemistry of diamond growth in a technique known as chemical vapour deposition (CVD). This is one of the main techniques for growing diamonds, the other being high temperature, high pressure (HPHT) techniques, which mimic the conditions in the Earth that lead to the natural formation of diamonds.

However, whilst HPHT techniques are excellent for making ‘industrial’ diamonds for coating saw blades or drill bits, there are some advantages to not having to use such extreme pressure and temperature conditions in the synthetic process.

With CVD, it is possible to grow thin films of diamond that can be less than a few micrometres thick that are exceptionally pure. The technique works by flowing a hydrocarbon gas mixture over a heated filament. The hydrocarbon molecules will react and decompose on coming into contact with the filament, and then deposit onto a nearby substrate to gradually build up a coating of diamond on the surface.

Much of this excitement stems from the excellent conductive properties of boron-doped diamond. When you couple this with many of the unique properties of diamond, its robustness, chemical inertness and excellent

INNOVATION

heat conductivity, you have the recipe for a substance with a huge number of potential applications, such as electronic devices, sensors, displays and electrochemical electrodes.

One application for these boron-doped diamond films that Professor May is particularly excited about is in human medicine. At present, one of the few surgical options available for the management of Parkinson’s symptoms is deep brain stimulation, a process which involves the implantation of electrodes into the brain that send out electrical impulses.

The chemical composition of diamond means it is one of few materials that do not trigger an immune response when implanted into the body. When this is combined with the conductive abilities of boron-doped diamond films, using these as an alternative to metal electrodes could

have a revolutionary impact for Parkinson’s patients, who could have diamond electrodes implanted which last decades or even the lifetime of the patient.

1894 Science-fiction visionary HG Wells publishes the short story, The Diamond Maker, about the lead character’s attempts to make artificial diamonds.

1954 Tracy Hall at General Electric produces the first commercially successful synthesis of diamond.

1970 The first synthetic gem-quality diamond crystals are produced by General Electric.

OUTREACH


The school’s Picture It… Chemistry blog delves deep into the chemistry of everyday substances. Here, Ben Mills looks at that staple of the British diet – beer. Here’s an extract…

- a bitter relationshipHops and beer

B eer is an important part of our civilisation. It’s been brewed across the world for thousands of

years as the alcohol content prevents the growth of microorganisms responsible for diseases caught from drinking dirty water. Nowadays water treatment purifies drinking water, but thanks to its long history, brewing beer has remained part of our culture and is now a major part of our economy.

Since the 19th century, brewing has evolved from a domestic to an industrial enterprise, and over the years we have learnt a great deal about the chemistry of one of beer’s main ingredients: hops. Not only do hops contain a huge variety of compounds, but also the same chemicals that give beer its flavour may become the medicines of tomorrow.

Beer today These days, beer is made from dried, germinated barley (malt), yeast, water and hops. These dried cone-shaped flowers of the hop plant, Humulus lupulus, were added to beer from the middle ages.

They clarify the beer, act as an antibiotic to preserve it, help to create the foam and are mainly responsible its aroma, flavour and bitterness. But where does the bitter taste actually come from? To understand this, we need to know how beer is made.

The most important brewing steps are mashing, boiling and fermenting. During mashing the starch in malt is broken down into sugars by naturally present enzymes called amylases. During boiling, the sugary solution is boiled with hops to remove some of the water and destroy the enzymes. Finally comes fermenting. The solution is cooled and yeast is added, converting the sugars into ethanol (alcohol) and carbon dioxide.

Both sugars (small soluble molecules) and starch (an insoluble polymer) are carbohydrates composed of carbon, hydrogen and oxygen in a 1:2:1 ratio. Carbohydrates are used by living organisms to store energy and release it on demand. The starch, a long chain of sugar molecules linked together by carbon-oxygen bonds, is broken down to sugars

Hops are the female flowers of the hop plant, Humulus lupulus

Skeletal formula of the hop terpenes humulene, myrcene and caryophyllene.

Skeletal formulae of humulone and isohumulone, two substances responsible for the bitter taste of beer.

Hops (Humulus lupulus)

Isohumulone (left) can be reduced to tetrahydroisohumulone (right) by hydrogen gas with a solid palladium-on-carbon catalyst suspended in methanol. Alkene groups in the prenyl side chains of isohumulone are reduced to alkanes.

humulene myrcene caryophyllene

H

H

OH

OH

HO

O

humulone isohumulone

OHHO

O

O O

OHHO

O

O O

alkenes

isohumulone

alkanes

tetrahydroisohumlone

1 atm H2 (g)10% Pd/C

MeOH

80-95% yield

O O

HOOH

O

O


H

H

OH

OH

HO

O


OHHO

O

O O

OHHO

O

O O

alkenes

isohumulone

alkanes



MeOH

80-95% yield

O O

HOOH

O

O


H

H

OH

OH

HO

O


OHHO

O

O O

OHHO

O

O O

alkenes

isohumulone

alkanes



MeOH

80-95% yield

O O

HOOH

O

O

when energy is required, while the sugars are put through a cascade of biochemical reactions to release their energy. When no oxygen is available (anaerobic conditions), only products containing the same amount of oxygen as the sugar contains can be generated – this is fermentation. In human muscle, sugars ferment to lactic acid, causing cramp. In yeast, sugars ferment to ethanol and carbon dioxide.

The boiling stageHops flowers contain a family of compounds called alpha-acids or humulones, which are organic molecules containing a ring of six carbon atoms. When heated, humulones undergo a reaction called an acyloin rearrangement, producing a new family of compounds - the iso-alpha-acids or isohumulones. These contain a smaller ring of five carbon atoms. During the boiling stage of brewing, the high temperature converts humulones to isohumulones, developing the distinctive bitter flavour of beer.

Isohumulones tend to react further, often decomposing to other isomers, oxidising or forming polymers. To avoid this instability, some breweries convert isohumulones into more stable compounds by extracting the isohumulones from hops and carrying out hydrogenation. Stable


Meet the chemist

Ben Mills is a postgraduate student in the group of Dr Charl Faul. In between contributing to Picture It…, he manages to find time to work on his PhD research, investigating organic compounds for use as materials in electronic devices. Ben recently returned from Japan, where he was working with chemists at Kyoto University on a joint project involving polymerisation reactions in liquid crystal solvents. He also demonstrates experiments at schools and in the second year undergraduate teaching laboratories. Outside of work, he enjoys climbing and pub quizzes, and attempts to play badminton.

Ben Mills

derivatives – tetrahydroisohumulones – can be added to the beer later to reach the desired degree of bitterness. While isohumulones are the main source of bitterness in beer, hops provide many other compounds that create the rich aroma and taste of beer. More than 150 fragrant molecules are present in hop oil, including some found in spices and flowers – grassy-smelling aldehydes, citrusy esters, floral and fruity geraniol and herbal oxidised sesquiterpenes.

Cancer preventionSeveral compounds in beer are being investigated as they may help prevent cancer and treat diabetes and inflammation.

Meanwhile, humulone also shows promising anti-cancer properties. Its precise structure was revealed in an American research article, helping

scientists to hopefully develop medicines based on molecules from hops.

Too good to be true? For anyone hoping to avoid cancer by heading to the pub, the authors were keen to point out that “excessive beer consumption cannot be recommended to propagate good health”.

SINCE THE 19TH CENTURY, BREWING HAS EVOLVED FROM A DOMESTIC TO AN INDUSTRIAL ENTERPRISE

About the Picture It… Chemistry blogDr Jenny Slaughter and Dr Natalie Fey started the Picture It... Chemistry blog as a means of talking about science in a way that anyone can understand. Each post is written by a collaborative team, bringing together research and ideas from technicians, administrative staff, academics, undergraduates, postgraduates and school students. As well as beer, other recent postings comment on diverse topics including the properties of marmalade, spearmint, bananas and aloe vera.

You can read the blog in full at chempics.wordpress.com

Take

th

e c

ha

llen

ge:

Th

e c

orr

ec

t a

nsw

er

is t

he

left

-ha

nd

sid

e m

ole

cu

le, c

om

me

rcia

lly k

no

wn

as

Pro

zac

, oft

en

use

d in

th

e tr

ea

tme

nt

of

de

pre

ssio

n.

Wh

ilst

bo

th m

ole

cu

les

fulfi

l th

e re

qu

ire

d p

rop

ert

ies,

it is

a d

ye, c

alle

d R

ed

-2G

pre

sen

t in

th

e ri

gh

t-h

an

d s

ide

mo

lec

ule

, wh

ich

is t

oxi

c if

co

nsu

me

d.

Hops in a box of ethanol wash bottles with molecular structures of humulone (left)

and isohumulone (right)

IT’S LATE JUNE, and School of Chemistry porter Jon May is enjoying the relaxed atmosphere of campus in summer, compared to the business of term time, when about 800 students can descend on the building at once. This is the calm before the storm, he jokes.

As the welcoming face of the school, he is the first point of contact for many students when they arrive, full of questions and queuing down the corridor. “In term-time it’s heaving,” he explains. “It gets a bit crazy when you’ve got one class going out and another one coming in, but it’s nice to be busy.” And, after working in the school for four-and-a-half years, there isn’t much he doesn’t know about its inner workings.

“The autumn term is the busiest time of year – it’s manic.” And it’s busier than ever since the schools started sharing lecture space. “We get to know the chemists, but now we have students from across the university here, there are even more people coming in and out.”

After doing the rounds, Jon’s duties include disposing of glass waste from the labs, manning reception and

welcoming visitors, including on one occasion the Mayor of Bristol, George Ferguson, who was giving a lecture.

“I was only planning on being here for six months,” he says, “but I’ll have been here 15 years soon!” After starting at the School of Veterinary Sciences, Jon moved to Engineering and then the Students’ Union, before coming to Chemistry for a promotion.

“Things in Chemistry are relatively tame compared to the union building,” he says, remembering one occasion when the BBC medical drama Casualty was filming there. “They changed the sign on the front, and a girl walked past and said in all seriousness, ‘When did the union become a hospital?’”

As we go to press, the students will soon be returning, and Jon is looking forward to the influx; working closely with the staff and students is his favourite part of the job. “It’s the people that make it,” he says.

Chemistry Explored hooks up with Jon May, the first point of contact for school newcomers

Meet the porter

INSIDE VIEW

Jon May has worked at the School of Chemistry for four-and-a-half years

“THE AUTUMN TERM IS THE BUSIEST OF THE YEAR – IT’S MANIC”


Meet the porterin numbers

INFOGRAPHIC

12The number of NMR spectrometers we will have in the School of Chemistry by early 2015.

The NMR magnets generate their enormous magnetic fields using superconducting wire that is cooled to just 4 degrees kelvin above absolute zero, or

-269 °C We also use sensitive electronic receivers that are kept very cold – one of our probes runs at the same temperature as the surface of the planet Pluto at only

20 kelvin. The temperature inside the magnet is over

colder than the coldest ever recorded on Earth.

We purchase and recycle nearly

8,000

Winchester solvent bottles a year.

In 2013 we disposed of

36,240 Lof solvent waste – all of which was recycled and reused as an alternative fuel source in things like cement kilns.

7.8G Whused each year in the school, the same as 1,600 homes and 20% of the precinct total.

4,000 boxes of disposable gloves used per year.

50-80parcels received daily from suppliers.

CHEMISTRY


100 °C

2,000 Lthe quantity of liquid Helium we use to fill our NMR magnets every year (for a price comparison – you could pour in one bottle of award-winning Scotch whisky every day for the same cost… that’s one shot an hour, all day, every day!).

400 The number of party balloons you could fill with the helium boil-off gas from our NMR magnets every day. And as it takes around 4,000 party balloons to lift the average person off the ground, you could achieve that goal in about 10 days if you put your mind to it.

1,000 kmthe total length of superconducting wire (mainly Nb3Sn and NbTi) contained in our NMR magnets.

Look out for the next issue of Chemistry Explored for images on the theme of catalysis. Send your entries to [email protected], including a JPEG image, a brief caption, and your name and address.

Bundles of Gold by Geri EchueThis is a Polarised Light Microscopy image of a liquid-crystalline material. Liquid crystals are an odd state of matter that sometimes behave a like a solid and sometimes like a liquid. They will flow like a liquid, but their particles line up in an ordered fashion, like a solid. They are used in many electronic displays, like flatscreen televisions.

Fantastic Voyage by Professor Mike Ashfold When an individual molecule absorbs light it may gain enough energy to break up into smaller molecules or atoms. The different rings in this image show all the different energies of the products formed. Analysis of such images can provide a very detailed understanding of the chemical bonds which hold molecules together.

Frog Chorus by Dr Simon Hall These are Bryozoa – coral-like animals which live on seaweed and rocks (and any passing ships!). These micro-organisms construct amazingly complex, chalky shells to provide individual compartments in which each animal lives. Some colonies can grow many metres in size, containing millions of individuals.

Life through a lensChem@rt is a University of Bristol initiative that brings chemistry into the classroom and stimulates literacy and creativity. Here are a small selection of the stunning images created by our scientists

Date post:	18-Jun-2020
Category:	Documents
Upload:	others
View:	0 times
Download:	0 times

JEWEL PURPOSE DISCOVER HOW SYNTHETIC DIAMONDS ARE …€¦ · Branded Content, Tower House, Fairfax...

Documents