Organic Photochromic and Thermochromic Compounds. Volume 1: Main Photochromic Families

Transcription

1 Organic Photochromic and Thermochromic Compounds Volume 1: Main Photochromic Families

2 TOPICS IN APPLIED CHEMISTRY Series Editors: Alan R. Katritzky, FRS University of Florida Gainesville, Florida Gebran J. Sabongi 3M Company St. Paul, Minnesota Current volumes in the series: ANALYSIS AND DEFORMULATION OF POLYMERIC MATERIALS Paints, Plastics, Adhesives, and Inks Jan W. Gooch CHEMISTRY AND APPLICATIONS OF LEUCO DYES Edited by Ramaiah Muthyala FROM CHEMICAL TOPOLOGY TO THREE-DIMENSIONAL GEOMETRY Edited by Alexandru T. Balaban LEAD-BASED PAINT HANDBOOK Jan W. Gooch ORGANIC PHOTOCHROMIC AND THERMOCHROMIC COMPOUNDS Volume 1: Main Photochromic Families Volume 2: Physicochemical Studies, Biological Applications, and Thermochromism Edited by John C. Crano and Robert J. Guglielmetti ORGANOFLUORINE CHEMISTRY Principles and Commercial Applications Edited by R. E. Banks, B. E. Smart, and J. C. Tatlow PHOSPHATE FIBERS Edward J. Griffith POLY(ETHYLENE GLYCOL) CHEMISTRY Biotechnical and Biomedical Applications Edited by J. Milton Harris RESORCINOL Its Uses and Derivatives Hans Dressler A Continuation Order Plan is available for this series. A continuation order will bring delivery of each new volume immediately upon publication. Volumes are billed only upon actual shipment. For further information please contact the publisher.

3 Organic Photochromic and Thermochromic Compounds Volume 1: Main Photochromic Families Edited by John C. Crano Late of PPG Industries, Inc. Monroeville, Pennsylvania and Robert J. Guglielmetti University of Aix-Marseille II Marseille, France Kluwer Academic Publishers NEW YORK, BOSTON, DORDRECHT, LONDON, MOSCOW

4 ebook ISBN: Print ISBN '2002 Kl uwer Academic Publishers New York, Boston, Dordrecht, London, Moscow All rights reserved No part of this ebook may be reproduced or transmitted in any form or by any means, electronic, mechanical, recording, or otherwise, without written consent from the Publisher Created in the United States of America Visit Kluwer Online at: and Kluwer s ebookstore at:

5 In Memoriam DR. JOHN C. CRANO On January 10, 1998 Dr. John C. Crano, 62, one of the co-editors of this book, and his wife Dorothy were killed instantly in an automobile accident in Florida. In this tragic death the world of photochromism has lost the person chiefly responsible for the success of the largest commercial application of organic photochromics. Dr. Crano received a B.S. degree in Chemistry in 1957 from Notre Dame and M.S. and Ph.D. degrees from Case Western Reserve University in 1959 and 1962, respectively. He joined PPG Industries in 1961, and had spent his entire career with that firm, at first in various roles in the Chemical Research & Development area. In 1974 PPG began research upon means to impart photochromic properties to ophthalmic lenses made from plastics, in particular from poly(allyl diglycol carbonate), CR-39 fi. Plastic lenses command over 85% of the total ophthalmic market in the US, principally because a lightweight plastic product is more comfortable to wear and permits more attractive fashion designs. Comparative testing of all classes of photochromics, including inorganic compounds, indolinospirobenzopyrans and naphthoxazines, occupied the first few years. In the early 1980 s expanding research and development efforts focused upon the indolinospirobenzoxazines and quinolinooxazines and their close structural relatives. In 1986 Dr. Crano become leader of a constantly enlarging team of organic, physical, polymer and photo chemists and engineers. The first generation plastic photochromic ophthalmic lenses, the Transitions fi Comfort Lens, were manufactured in Ohio and test-marketed in June of Transitions Optical. Inc., a joint venture between PPG and the French lens manufacturer Essilor, was formed in 1990 and began manufacturing lenses early in 1991 in a new plant in Florida. A second generation lens, the Transitions fi Plus lens, was introduced in November In the years since, Transitions Optical has marketed a succession of new lenses. In September 1994 the EuroBrown lens appeared, formulated to give when activated a brown color, especially favored in the European market. The mid-index Transitionsfi III lenses were launched in the United States and in Europe during 1996, and the Transitions XTRActive lenses were introduced in the US in January The most recently introduced lenses are Transitionsfi III lenses in a standard index matrix. These use the latest technology in organic photochromic dyestuffs and polymer science and engineering, and maintain the company s position v

6 vi In Memoriam of technical leadership in the field of plastic ophthalmic photochromic lenses. Transitions Optical now sells its various lenses in over 50 countries. In his position as Associate Director of Research and Development, Optical Products, Dr. Crano managed the entire photochromics research program. He led the team of scientists that synthesized and evaluated hundreds of candidate photochromic dyestuffs, and directed all of the product and process development involved in the various Transitions fi lenses. In addition, his responsibilities included R&D on non-ophthalmic photochromic applications, and on other optical coatings and resins. He has a number of US patents in various areas of technology, including three during that cover the basic compositions and methods for producing the first generation of Transitions fi lenses. These were important in establishing a strong proprietary position in photochromic plastic ophthalmic lenses. In addition, he had published several reviews and invited lectures on photochromism and photochromic polymers. In 1985 he was General Chairman of the Central Regional Meeting of the American Chemical Society, and in September 1996 he was Co-Chairman of the 2nd International Symposium on Photochromism. This Symposium, which included participants from 16 countries, owed much of its success to Dr. Crano s excellent organization.

7 John C. Crano ( )

8 Recent Publications and Presentations of J. C. Crano Photochromic Systems for Plastic Ophthalmic Lenses, J. C. Crano, 1997 Gordon Conference on Organic Photochemistry. Photochromic Compounds: Chemistry and Application in Ophthalmic Lenses, J. C. Crano, T. Flood, D. Knowles, A. Kumar and B. Van Gemert, Pure Appl. Chem, 68(7), (1996). Photochromic Materials, John C. Crano, in Kirk-Othmer Encyclopedia of Chemical Technology, 4th Ed., 1993,. J. Wiley & Sons, New York. Photochromic Organic Compounds in Polymer Matrices, J. C. Crano, C. N. Welch, B. Van Gemert, D. Knowles and B. Anderson, in Photochemistry and Polymeric Systems, J. M. Kelly, C. B. McArdle and M. J. de F. Maunder, Eds., 1993, Royal Society of Chemistry, Cambridge. Spirooxazines and Their Use in Photochromic Lenses, J. C. Crano, W. S. Kwak and C. N. Welch, in Applied Photochromic Polymer Systems, C. B. McArdle, Ed., 1992, Blackie and Sons. R. Guglielmetti and R. Bertelson viii

9 Foreword Experiments showing a rapid and reversible change of color seem to be magic and are always fascinating. This process called photochromism, has a few real and many potential applications. Photochromic glasses that darken in the sunlight (protecting eyes from excessive light intensity) and bleach in dim light are today a part of everyday life. Organic Photochromic Compounds in plastic ophthalmic lenses, more comfortable to wear, are now competing with silver salts glasses, despite the longer lifetime of the inorganic system. This successful commercial application has given a new impetus to research in the general field of photochromism that had its most recent revival in the early eighties. The story of organic photochromism with its ups and downs, from the breakthroughs of the pioneering period in the fifties, through the hard times due to the drawbacks of photodegradation and the recent successes is in many ways a saga. The upsurges in the domain were marked by an increasing flow of articles in scientific journals and the publication of several Books (in 1971, 1990 and 1992) which have collected the important accumulated knowledge. Over this period, a considerable number of patents have been issued. International meetings have accompanied this activity, the most recent being held in 1993 ( ISOP-93 at Les Embiez Island, France) and in 1996 (ISOP-96 in Clearwater, Florida, USA). Remarkably, these meetings had a good representation from both academia and industry. The next ISOP is planned for 1999 in Fukuoka, Japan. Since publication of the most recent Books, new areas have been explored and a large number of new results have been obtained and it seemed, therefore, timely to publish them. This was the endeavor of the chairmen of ISOP-93 and ISOP-96, Robert Guglielmetti and John Crano, respectively, who have acted as co-editors. R. Guglielmetti, a professor at the University of Marseilles is a recognized leader in the field and the late Dr. J. Crano, Associate Director of Research and Development for optical products at PPG since 1986, led research in the development of plastic ophthalmic eyewear. The efficient cooperation of a scholar and an industrial scientist has led to the Book entitled: Organic Photochromic and Thermochromic Compounds in two volumes of about 400 pages each. Volume 1 includes nine chapters, the first six of these deal with the main established families of organic photochromes which have a few real and many potential applications. Their photochemical processes are based on pericyclic electrocyclic reactions. The three other chapters concern hydrogen or group rearrangement, and electron transfer. Seven out of the nine main authors, selected from all over the world, have not written chapters for previous books and importantly, three are from companies. Four chapters cover families not reviewed ix

10 x Foreword in the previous books while the other five have been renewed and updated (until ). A useful initiative is the introduction of detailed preparations of some representative examples of spiropyrans, spirooxazines, chromenes, fulgides, spirodihydroindolizines, aryloxyquinones and perimidinespirocyclohexadienones. It should be noted that Volume 1 does not address thermochromism. Indeed, it will be obvious to the reader that this volume is not a remake of the preceding Books. Organic photochromic systems have actual applications in variable transmission optical materials, authentication systems and novelty items. In addition, they offer great potential in erasable optical memories and many other fields where reversible changes of physical properties other than color are wanted. The domain is interdisciplinary and expanding. Volume 1 can be read independently but the material contained in Volume 2 is intended to be complementary. The Book is strongly recommended to photochromism practitioners as well as anyone interested in Materials Science. Henri Bouas-Laurent University Bordeaux 1 April 1998

11 Alphabetical Contributors List Name/Affiliation Angelo Alberti, CNR (I.Co.C.E.A.) Bologna, Italy Serguei Aldoshin, Academy of Sciences, Institute of Chemical Physics, Chernogolovka, Russia Jean Aubard, Itodys, Denis Diderot University Paris 7, CNRS URA 34, Paris, France Valeri Barachevsky, Academy of Sciences, Semenov Institute of Chemical Physics, Moscow, Russia Robert Bertelson, Chroma-Chemicals, Inc., Dayton, Ohio John Crano, PPG Industries, Monroeville, Pennsylvania Heinz Dürr, Sarbr cken University, FR 11.2 Organische Chemie, Saarbr cken, Germany Mei Gong Fan, Chinese Academy of Sciences, Institute of Photographic Chemistry, Beijing, China Robert Guglielmetti, MØditerranØe University, FacultØ des Sciences de Luminy, Marseille, France Kunihiro Ichimura, Tokyo Institute of Technology, Research Laboratory of Resources Utilization, Yokohama, Japan Masahiko Inouye, Osaka Prefecture University, Department of Applied Materials Science, Osaka, Japan xi

12 xii Alphabetical Contributors List Masahiro Irié, Kyushu University, Institute of Advanced Materials Study, Fukuoka, Japan Shuichi Maeda, Mitsubishi Chemical Corporation, Yokohama Research Center, Imaging Materials Laboratory, Yokohama, Japan Vincenzo Malatesta, Great Lakes Chemical Italia, s.r.l., Milano, Italy Albrecht Mannschreck, Regensburg University, Institute f r Organische Chemie, Regensburg, Germany Jean-Claude Micheau, Paul Sabatier University, URA CNRS 470, Toulouse, France Vladimir Minkin, Rostov/Don University, Institute of Physical and Organic Chemistry, Rostov/Don, Russia Shinichiro Nakamura, Mitsubishi Chemical Corporation, Research and Development Division, Yokohama, Japan Masata Nanasawa, Yamanashi University, Department of Applied Chemistry and Biotechnology, Yamanashi, Japan André Samat, MØditerranØe University, FacultØ des Sciences de Luminy, Marseille, France Barry Van Gemert, PPG Industries, Monroeville, Pennsylvania

13 Preface This book, Organic Photochromic and Thermochromic Compounds, is the fourth major treatise on photochromism involving organic molecules and derived systems. The first such book was edited by G. H. Brown in the Weissberger series in 1971, the second was edited by H. D rr and H. Bouas-Laurent in the Elsevier series in A third book, edited by C. B. McArdle, should be added to the list, which focuses on the very important topic of the behavior of photochromic systems in polymer matrices. The current book is an outgrowth of the large increase in the number of publications and patents concerning photochromic compounds and their use in various applications (e.g., ophthalmic lenses and security printing) during the past 10 years. As a result of this increased interest, two successful international symposia on photochromism have been held: the first was ISOP93, held in France on Embiez Island near Bandol (September 12 16, 1993) and the second, was ISOP96, held in the United States in Clearwater, Florida (September 8 12, 1996). The number of countries represented at each of these symposia (17 and 16, respectively) attests to the international scope of the photochromic research community. The increased international literature on syntheses and physicochemical investigations of photochromic phenomena led the Editors and the Publisher to divide Organic Photochromic and Thermochromic compounds into 2 volumes. The first volume deals with the synthesis and specific photochromic properties of the best-known classes and their field of application; it contains 9 chapters. The aim of this new review, which is focused on organic photochromic compounds but also contains a brief survey on thermochromic compounds, is to give practical information involving selected series with the hope that this will lead to additional commercial applications for known photochromic families or to the discovery of new families. To make this volume more useful, almost all the chapters covering specific families of photochromic compounds include general methods for preparing members of each family, along with synthetic procedures for specific examples. Where possible, photochromic behavior (spectrokinetic parameters, photostability) in solution or in polymer matrices, and potential applications are described. We did not emphasize the theoretical aspect of the different photochromic processes because of their coverage in a fairly recent treatise (D rr, Bouas-Laurent ). In general, the literature cited within the chapters covers publications through However, in several cases, publications from as late as 1997 are included. xiii

14 xiv Preface Our thanks go to all the colleagues who volunteered to collaborate on this book and who had the patience and reliability to undertake all the steps required to prepare the final manuscripts. In addition to the chapter authors, several other people have contributed their time and talent to the completion of this book. Dr. A. Samat and Dr. V. Lokshin (Laboratory of Organic Chemistry and Materials of Marseille) must be acknowledged for many fruitful discussions during the entire process of assembling the book. We are deeply indebted to Diana Gronholm, PPG Industries, Inc., whose help in the revision and copying of manuscripts, communications with contributors and the publisher, and a variety of other tasks during the preparation of the book was invaluable. Dr. Anil Kumar, also with PPG, helped with the conversion of files into usable program formats and technical assistance in the preparation of files for the final manuscripts. Finally, we express our appreciation to Audrey Anderson, Denise Callihan and Beverly Weston with PPG Industries for their assistance in obtaining missing titles of several references and general assistance when it was needed to verify details of references. 1. Photochromism (G. H. Brown, ed.) Techniques Chem. Vol. III, Wiley Interscience, New York (1971). 2. Photochromism: Molecules and Systems (H. D rr, H. Bouas-Laurent, eds.) Elsevier, Amsterdam (1990). 3. Applied Photochromic Polymer Systems (C. B. McArdle, ed.) Blackie, New York, J. C. Crano and R. Guglielmetti

15 Table of Contents Introduction 1. Aim and Organization of the Book Brief Historical Survey of Photochromism Definitions of Photochromism Brief Analysis of the Different Chapters and their Main Topics Conclusion and Future Developments References Spiropyrans Robert C. Bertelson 1.1. Introduction Synthesis General Summary Intermediates for Spiropyrans Fischer s Base Syntheses Fischer s Base Salts by Alkylation of Indolenines Fischer s Bases from Oxindoles Fischer s Bases by Oxidation of Indolines Substitution in Fischer s Bases Preparations of Indolenines Preparation of Indoles Preparations of Spiropyrans Substitution in Spiropyrans New Materials. Properties and Structure Property Relationships Spiropyrans in Fluid Solutions Spiropyrans with Long-wavelength Absorption Spiropyrans as Vapor-Deposited and Amorphous Films Polymeric Spiropyrans xv

16 xvi Table of Contents Spiropyran Aggregates Mechanistic Studies: Photocoloration, Photodecoloration, Fatigue and Photodegradation Reactions of Spiropyrans with Inorganic Reagents Spiropyrans in Sol Gel Matrices Quantum Mechanical Calculations Optically Active Spiropyrans Applications and Future Trends Some Representative Preparations NitroBIPS Phenyl Fischer s Base and its Hydroiodide Formylsalicylaldehyde References Spirooxazines Shuichi Maeda 2.1. Introduction Structure, Synthesis, and Photochromic Properties Substitution on the Naphthoxazine Ring Moiety Substitution on the Indoline Ring Moiety Other Indolinospirooxazines Miscellaneous Spirooxazines Chelation of Spirooxazine Derivatives Crowned Spirooxazines Electropolymerization of Spironaphthoxazine Thiophene Derivatives Molecular Structure and Mechanism of the Photochromic Reactions Nature of the Closed Form Nature of the Colored Form Mechanism of the Photochromic Reactions Applications Stabilization of Spirooxazines Commercial Plastic Photochromic Lenses Microencapsulated Photochromic Ink Photochromic Lamiglass Synthesis Examples Synthesis of 1,3,3-trimethylspiro[indoline-2,3 -[3H]naphth]- [2,16][1,4] oxazine] (Compound 1) Synthesis of 6 -indolino-1,3,3-trimethylspiro[indoline-2,3 -[3H]- naphth[2,1- b][1,4]oxazine] (Compound 7) Synthesis of 1,3,3 -trimethylspiro[3h-naphth][2,1-b][1,4]- oxazine-3,2 -piperidine (Compound 16)

17 Table of Contents xvii Synthesis of Compound References Benzo and Naphthopyrans (Chromenes) Barry Van Gemert 3.1. Introduction Definition Historical Perspective Current Review Photochromic Mechanism Performance Testing Fatigue Testing Fatigue Specific to Pyrans Stability and Stabilization H-Naphtho[2,1- b]pyrans Nomenclature Structure Photochromic Activity Relationships Substitution at the 1- and 2-Positions Substitution at the 3-Position Pyran Substitution via Heteroaromatic Annellation Substitution at the 5-Position Substitution at the 6-Position Substitution at the 8-Position Substitution at the 7, 9, and 10-Positions General Note H -Naphtho[1,2- b]pyrans Nomenclature Substituent Effects Substitution at the 2-Position Substitution at the 5-Position H-Naphtho[2,3- b]pyrans H-1-Benzopyrans (Chromenes) General Substituent Effects Synthetic Methods Preparation of 3,3-Diphenyl-3H-naphtho[2,1- b]pyran Preparation of 2-Methyl-7,7-diphenyl-7H-pyranol[2,3- g ]- benzothiazole Preparation of 2,2 -Spiroadamantylidene-2H-naphtho[1,2- b]- pyran Concluding Remarks References

18 xviii Table of Contents 4. Fulgide Family Compounds: Synthesis, Photochromism, and Applications Mei Gong Fan, Lianhe Yu, and Weih Zhao 4.1. Introduction Fulgides with Aromatic Ring Systems Phenyl Fulgides Nuclear Magnetic Resonance Spectroscopy X-Ray Crystallography UV-Visible Spectroscopy Photochromic Reactions, Substituent Effects and Fatigue Resistance of Phenyl Fulgides Miscellaneous Aryl Aromatic Fulgides Fulgides with Heterocyclic Ring Systems Furyl Fulgides Thienyl Substituent Effects on the Quantum Yield of Photochromic Reactions of Furyl Fulgides α -Alkyl Substituent Effects on the Photochromism of Furyl Fulgides Steric Effects on the Photochromic Behavior of the Alkylidene Group of Furyl Fulgides Comprehensive Steric Effect on the Quantum Yield of the Photoreactions of Furyl Fulgides Photochromism of Furyl Fulgides in Polymer Matrices. 160 Crystal Structures of Furyl Fulgides Helical Chirality of Furyl Fulgide Fulgides Indolyl Fulgides Pyrryl Fulgides Absorption Spectra of Fulgide 62 and its Colored Form (63) The Effect of Solvent Polarity on the Absorption Spectra of Fulgide 62 and its Colored Form (63) Substituent Effects on the Absorption Spectra of Pyrryl Fulgide 62 and Colored Forms (63) Crystal Structure of Fulgide 62n Heteroaromatic Fulgides Containing two Hetero Atoms Fulgimides, Isofulgimides, Fulgenates, Fulgenolides and Dicyanomethylene Derivatives of Fulgides Fulgimides Isofulgimides Fulgenates and Fulgenolides Tetrahydrofuran-2-one Derivatives Photochromic Mechanism Chromophores and Excited States of Fulgides E Z Isomerization

19 Table of Contents xix Photocyclization Reactions of Fulgides and Derivatives Heliochromic Reaction Applications of Fulgides and their Derivatives Optical Storage Actinometry Photochromic Inks, Paints and Fabrics Applications in Other Advanced Materials Some Examples of Detailed Syntheses References Diarylethenes with Heterocyclic Aryl Groups Masahiro Irie 5.1. Introduction Synthesis Diarylperfluorocyclopentenes Diarylmaleic Anhydrides Properties Thermal Stability Fatigue-Resistant Character Absorption Spectra Response Time Molecular Systems with Controlled Functionality Gated Reactivity Photoswitching of Electrochemical Properties Conclusion References Photochromism of Dihydroindolizines and Related Systems Heinz Dürr 6.1. Introduction Syntheses of Photochromic Molecules Based on a 1,5-Electrocyclic Reaction Type 2 System Cyclopropene: Route (a) Pyrazole Route (b) Retro-1,5-Electrocyclization: Route (c) Diazo: Route (d) Tetrahydro- and Hexahydroindolizines Biphotochromic Systems Route 1: Type a and Type b Systems Type c Systems

20 xx Table of Contents 6.3. Photochromic Systems with One Heteroatom Spectra of the Colorless and the Colored Forms Spectra of Colored Forms Solvent Effects on the Colored Forms Thermal Reactions in Solution/Structure Fading Rate Relationships Modified Systems: Tetra and Hexahydroindilizines Mechanism of Photocoloration Quantum Yield of Photocoloration and Photobleaching Photochromic Systems Based on Pentadienyl Anions with Two Heteroatoms Type 1,2 Systems Type 2,3 Systems Photochromic Systems Based on Pentadienyl Anions with Three Heteroatoms Supramolecular and Environmental Effects and Applications Supramolecular Systems Photochromic Systems in Liquid Crystalline Phase Photochromic Systems in Polymers DHI Dissolved in Polymers Polymer-Linked Systems IR-Sensitive Materials Description of Apparatus Syntheses of Key Examples Conclusions References Photochromic Quinones Valeri Barachevsky 7.1. Introduction Synthesis of Photochromic Quinones Methylnaphthoquinone Derivatives of Anthraquinone Derivatives of Naphthacenequinone Phenoxypentacenequinone and Derivatives of Phthaloylpyrene Mechanism of Photochromic Transformations in Quinones Photochromism of Naphthoquinone Photochromism of Anthraquinones Alkylanthraquinones Acyloxyanthraquinones Aryloxyanthraquinones Anthrapyridones and Anthrapyridines Pyrazoloanthrones

21 Table of Contents xxi Photochromism of Naphthacenequinones Aryloxynaphthacenequinones Naphthacenepyridones and Naphthacenepyridines Pyrone Pyrazolonaphthacenones Photochromism of Phenoxypentacenequinone and Derivatives of Phthaloylpyrene Photochromic Behavior of Quinones Spectral Characteristics Kinetic Fatigue Characteristics Methylnaphthoquinone Derivatives of Anthraquinone Derivatives of Naphthacenequinone Methylnaphthoquinone Derivatives of Anthraquinone Derivatives of Naphthacenequinone Applications of Photochromic Quinones Recording and Multiplication of Images Optical Memory Gradation Masking Conclusion Examples of Synthesis of Photochromic Quinones Phenoxy-2,4-dioxy and 1-(p tert-butyl)phenoxy-2,4- dioxyanthraquinones Phenoxy-5,12-naphthacenequinone Phenoxy-5,12-pentacenequinone ,3-Dichloro-6-phenoxy-7,12-phthaloylpyrene References Perimidinespirocyclohexadienones Vladimir Minkin, Vitaly Komissarov, and Vladimir Kharlanov Introduction Synthesis and Reactions Spectral and Photochromic Properties Thermal Decoloration Reaction Thermo- and Solvatochromism Integrated Photochromic and Electrochromic Properties Photoinitiated Interconversion of Ring-Chain Isomers of bis-quinone Imines Derived from Aromatic Diamines Preparative Procedures ,3-Dihydro-2-spiro-4 -(2,6 -di-tert-butylcyclohexadien-2,5 - one) perimidine, 1a (R = H)

22 xxii Table of Contents Methyl-2,3-dihydro-2-spiro-4 -(2,6 -di-tert-butylcyclohexadien-2,5 -one) perimidine, 1a (R=CH 3 ) ,3-Dihydro-2-spiro-4 -[(4H)-2,-tert-butylnaphthalen-1 - one]perimidine, 4 (R,R,RR"=H) ,7,9-Trimethyl-2,3-dihydro-2-spiro-4 -(2,6 -di-tert-butylcyclohexadien-2,5 -one)-pyrido-[4,3,2-d,e]quinazoline, 9 (R =H, R=Me, Ar=H) References Photochromism by Electron Transfer: Photochromic Viologens Masata Nanasawa 9.1. Introduction to Photochromism by Electron Transfer Photochromism of Viologens Introduction General Synthetic Methods Photochromic Behavior Effect of Matrices on Photochromism A Variety of Color Species of Viologens Photochromism of Molecular Assembly Viologen Bearing a Metal Complex as Counteranion Applications Photochromism of Thiazines Introduction Photochromic Properties Applications Thiazine Dyes Effect of the Kind of Reductants Effect of Coating Substrate References Index