Photochromic Materials - Preparation, Properties and Applications

He Tian received his PhD in 1989 from the East China University of Science & Technology (ECUST) in Shanghai, China. From 1991 to 1993, he stayed at the University of Siegen, Germany, as a postdoc supported by the Alexander von Humboldt Foundation. In 1999, he was appointed Cheung Kong Distinguished Professor by the Education Ministry of China. He was selected as a member of the Chinese Academy of Science (2011) and a Fellow of The World Academy of Sciences (TWAS) ? for the advancement of science in developing countries (2013). His current research interests include the syntheses of novel functional organic dyes and development of interdisciplinary materials science that determines the electronic and optical properties of materials. Junji Zhang received his PhD from East China University of Science and Technology (ECUST) in Shanghai, China, in 2012 under the supervision of Professor He Tian. From 2010 to 2011, he stayed at the Hebrew University of Jerusalem, Israel, as an exchange doctoral student supported by the Chinese Scholarship Council (CSC). He is currently working as a lecturer, and his research interests are mainly focused on the photochromic materials, functional organic dyes and supramolecular switches.

List of Contributors XI 1 Introduction: Organic Photochromic Molecules 1 Keitaro Nakatani, Jonathan Piard, Pei Yu, and Remi Metivier 1.1 Photochromic Systems 1 1.1.1 General Introduction 1 1.1.2 Basic Principles 4 1.1.3 Photochromic Molecules: Some History 5 1.2 Organic Photochromic Molecules: Main Families 8 1.2.1 Proton Transfer 9 1.2.2 Trans Cis Photoisomerization 12 1.2.3 Homolytic Cleavage 13 1.2.4 Cyclization Reaction 14 1.2.4.1 Spiropyrans, Spirooxazines, and Chromenes 14 1.2.4.2 Fulgides and Fulgimides 17 1.2.4.3 Diarylethenes 18 1.3 Molecular Design to Improve the Performance 20 1.3.1 Figures of Merit 20 1.3.2 Fatigue Resistance: Increasing the Number of Operating Cycles 21 1.3.3 Bistability: Avoiding Unwanted Thermal Back-Reaction in the Dark 23 1.3.3.1 Influence of Ethenic Bridge on theThermal Stability of the B Form 24 1.3.3.2 Impact of the Heteroaryl Substituents on theThermal Stability of the B Form 24 1.3.4 Fast Photochromic Systems: Reverting Back Spontaneously to the Colorless State in a Glance 25 1.3.5 Gaining Efficiency of the Photoreaction: the Example of Diarylethenes 26 1.4 Conclusion 31 Irradiation at a Specific Wavelength: Isosbestic Point 32 Case A: When the Thermal Back-Reaction is Negligible Compared to the Photochemical Reaction (Typically P-type) 33 Case B: When the Thermal Back-Reaction is More Efficient than the Photochemical B A Reaction (Typically Type) 34 References 34 2 Photochromic Transitional Metal Complexes for Photosensitization 47 Chi-Chiu Ko and Vivian Wing-Wah Yam 2.1 Introduction 47 2.2 Photosensitization of Stilbene- and Azo-Containing Ligands 48 2.3 Photosensitization of Spirooxazine-Containing Ligands 51 2.4 Photosensitization of Diarylethene-Containing Ligands 54 2.5 Photosensitization of Photochromic N C-Chelate Organoboranes 63 2.6 Conclusion 65 References 66 3 Multi-addressable Photochromic Materials 71 Shangjun Chen, Wenlong Li, and Weihong Zhu 3.1 Molecular Logic Gates 71 3.1.1 Two-Input Logic Gates 71 3.1.2 Combinatorial Logic Systems 74 3.1.2.1 Half-Adder and Half-Subtractor 74 3.1.2.2 Keypad Locks 77 3.1.2.3 Digital Encoder and Decoder 82 3.2 Data Storage and Molecular Memory 84 3.2.1 Fluorescence Spectroscopy 85 3.2.2 Infrared Spectroscopy 90 3.2.3 Optical Rotation 92 3.3 Gated Photochromores 95 3.3.1 Hydrogen Bonding 95 3.3.2 Coordination 98 3.3.3 Chemical Reaction 99 References 105 4 Photoswitchable Supramolecular Systems 109 Guanglei Lv, Liang Chen, Haichuang Lan, and Tao Yi 4.1 Introduction 109 4.2 Photoreversible Amphiphilic Systems 110 4.2.1 Photoreversible Diarylethene-Based Amphiphilic System 110 4.2.2 Photoreversible Azobenzene-Based Amphiphilic System 116 4.2.3 Photoreversible Spiropyran-Based Amphiphilic System 119 4.3 Photoswitchable Host Guest Systems 122 4.3.1 Photocontrolled Supramolecular Self-Assembly 123 4.3.2 Photocontrolled Capture and Release of Guest Molecules 128 4.3.3 Fluorescent Switching Promoted by Host Guest Interaction 133 4.3.4 Photoswitchable Molecular Devices 137 4.4 Photochromic Metal Complexes and Sensors 141 4.4.1 Metal Complexes with Azobenzene Groups 141 4.4.2 Metal Complexes with Diarylethene Groups 144 4.4.3 Metal Complexes with Spirocyclic Groups 150 4.4.4 Metal Complexes with Rhodamine 152 4.5 Other Light-Modulated Supramolecular Interactions 153 4.6 Conclusions and Outlook 159 References 159 5 Light-Gated Chemical Reactions and Catalytic Processes 167 Robert Gostl, Antti Senf, and Stefan Hecht 5.1 Introduction 167 5.2 General Design Considerations 169 5.3 Photoswitchable Stoichiometric Processes 171 5.3.1 Starting Material Control 172 5.3.2 Product Control 175 5.3.3 Starting Material and Product Control 177 5.3.4 Temp