Chromic Phenomena: Technological Applications of Colour Chemistry

Chromic Phenomena Technological Applications of Colour Chemistry Chromic Phenomena Technological Applications of Colour Chemistry Peter Bamfield Penarth, UK Email: [email protected] and Michael Hutchings Holcombe, Bury, UK Email: [email protected] Print ISBN: 978-1-78262-815-6 PDF ISBN: 978-1-78801-284-3 EPUB ISBN: 978-1-78801-503-5 A catalogue record for this book is available from the British Library r Peter Bamfield and Michael Hutchings 2018 All rights reserved Apart from fair dealing for the purposes of research for non-commercial purposes or for private study, criticism or review, as permitted under the Copyright, Designs and Patents Act 1988 and the Copyright and Related Rights Regulations 2003, this publication may not be reproduced, stored or transmitted, in any form or by any means, without the prior permission in writing of The Royal Society of Chemistry or the copyright owner, or in the case of reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency in the UK, or in accordance with the terms of the licences issued by the appropriate Reproduction Rights Organization outside the UK. Enquiries concerning reproduction outside the terms stated here should be sent to The Royal Society of Chemistry at the address printed on this page. Whilst this material has been produced with all due care, The Royal Society of Chemistry cannot be held responsible or liable for its accuracy and completeness, nor for any consequences arising from any errors or the use of the information contained in this publication. The publication of advertisements does not constitute any endorsement by The Royal Society of Chemistry or Authors of any products advertised. The views and opinions advanced by contributors do not necessarily reflect those of The Royal Society of Chemistry which shall not be liable for any resulting loss or damage arising as a result of reliance upon this material. The Royal Society of Chemistry is a charity, registered in England and Wales, Number 207890, and a company incorporated in England by Royal Charter (Registered No. RC000524), registered office: Burlington House, Piccadilly, London W1J 0BA, UK, Telephone: þ44 (0) 207 4378 6556. Visit our website at www.rsc.org/books Printed in the United Kingdom by CPI Group (UK) Ltd, Croydon, CR0 4YY, UK Preface to the Third Edition As soon as we had been invited by the Royal Society of Chemistry to write a third edition of ‘‘Chromic Phenomena’’, following the first and second editions published in 2001 and 2010, the daunting scale of the new task became apparent. Later in the process we quantified exactly how daunting by researching the information explosion we have been faced with. A search of Royal Society of Chemistry publication data reveals about a dozen key topics where there are more than ten times the amount of publications recently than we dealt with in the preceding edition of this book. (Notwithstanding new arrivals with zero hits previously, the record appears to be for ‘‘upcon- version’’ which occurs in article titles an astonishing 48 times more fre- quently between 2010 and 2016 as the preceding seven-year period between 2003 and 2009.) Across all 50 or so topics we checked, the average increase is about eight times. We provide a more detailed breakdown of these publication statistics in Appendix 2. So from the outset we felt a radical revision was desirable. We have eliminated the original Chapter 2 which covered basic colouration phenomena and applications, mainly on the basis that new work in this area had atypically become limited. However, as an aide memoire for our read- ership, a description of the main chromophores used in classical dyes and pigments is given Appendix 1. Elsewhere we have also cut back topics dealing with more or less obsolete technology (e.g. the cathode ray tube), but even here not completely as we feel that putting the ongoing development of certain topics within an historical perspective is important, for example optical data storage. This still left difficult decisions on how to give a fair and balanced coverage of new and expanding subjects. As we stand back and survey the finished manuscript, it is clear that while the use and development of the classical chromisms continues to grow, colour applications in the life sciences have required a much expanded coverage, from the point of view of what we can refer to as analysis (imaging, sensing) and treatment Chromic Phenomena: Technological Applications of Colour Chemistry By Peter Bamfield and Michael Hutchings r Peter Bamfield and Michael Hutchings 2018 Published by the Royal Society of Chemistry, www.rsc.org v vi Preface to the Third Edition (photodynamic and photothermal). In the seven years before 2010, there were no Royal Society of Chemistry titles containing the key words ‘‘theranostics’’, ‘‘nanoplasmonic’’, or ‘‘mechanochromism’’. Since then each has appeared in a substantial number of article titles. Other areas have required significant rewrites, including applications in solar energy, the next generation of display technologies, and bioinspired structural colours. It is also clear that our efforts to restrict the size of this edition have not been entirely successful. It now extends to 782 pages compared with the 562 of the second edition. Despite this, no doubt we have unwittingly omitted significant science and technology, for which we can only apologise to the responsible scientists. Besides the sheer volume of published science, not to mention the devices and products that result from its application, colour-related topics continue to be recognised at the highest level by awards of Nobel Prizes. Following on from green fluorescent protein in 2008, 2010 saw the recognition of graphene (physics) whose optical properties bring it into this book as a new material. In 2014 innovation of the blue LED and super-resolution microscopy were recognised by the physics and chemistry awards, respectively, both again fea- turing in later chapters. The chemistry award in 2016 for molecular machines is particularly significant for us given that one of the prize winners, Sir Fraser Stoddart, was a one-time, if temporary, colleague of ours in ICI where he readily admits much of his thinking that led to molecular machines started. We gratefully acknowledge the expert advice and comment from willing and enthusiastic contacts in response to queries. Miss Susannah Penney, Consultant Surgeon at Central Manchester NHS Foundation Trust, provided valuable observations on image guided surgery. Noor van der Veeken and Dr Toon Coenen of DELMIC B. V., Delft, The Netherlands, gave important advice on cathodoluminescence in general, and their SPARC microscope in particular. Besides the production team at the Royal Society of Chemistry, we also thank Dr Aileen Day and Dr John Boyle and colleagues in the Data Science team at the Royal Society of Chemistry for carrying out user access searches, and for advising us on our own publication statistics searches. Now that the task of pulling this new edition together is complete, we shall be able to revert to our gentle part-time retirements and re-continue Alpine and Pyrenean cycling, poetry, bass-playing, golf, attending to two and a half thousand adolescent trees, and still carry out a professional half-time job on computer aided synthesis software which somehow happily continued along- side the distraction of what we call CP3. Above all, we shall especially be able to give more and over-due attention to our long-suffering wives Domini and Julie who, as before, have had to put up with our absences in front of the computer screens that tried to teach us rather more about modern colour chemistry and its applications than we were prepared for. Thanks and hugs to both. Peter Bamfield Michael Hutchings [email protected] [email protected] Introduction Most of us go about our daily activities without paying much conscious attention to colour, except on the occasions when we are choosing what to wear or making a choice of cosmetics, judging the ripeness of fruit and without fail whilst waiting for traffic signals to change. In fact a quick audit would show that colour plays an extremely important and essential role in our everyday lives. Fortunately, total colour blindness is a rarity, but think what it must be like for those people for whom it is an inherited condition.1 Why colour is so important has exercised the minds of some of our greatest philosophers for many centuries.2,3 What is colour, what role does it play in Nature, and in our social and intellectual environment? Even today the answers to these questions are far from known and arguments over the psychological and social impact of colour continue to rage.4,5 However, ever since Newton recognised the relationship between light and colour in the late 17th century, our understanding of the hard science behind colour and its many applications has been increasing gradually, until it has reached today’s level of sophistication.6–8 Rather interestingly, a marriage between our understanding of the physics and chemistry of colour and their util- isation in both art and technology has become a topic of interest to many authors.9,10 Obviously the main use of colour in technology is to impart a visual stimulus as part of the overall aesthetic of the object being viewed. Whether this is in the coloration of textiles, plastics, paper, and hair or on a myriad of surfaces including wood, paper and metals, etc., an essential factor is its long-term stability to light. Yet colour can have less obvious applications beyond its position on the colour spectrum and its stability to light. Colour can be an enabler. We shall meet many applications where the actual colour is unimportant.

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