<p>List of Contributors XI</p> <p><b>1 Introduction: Organic Photochromic Molecules 1</b><br /><i>Keitaro Nakatani, Jonathan Piard, Pei Yu, and Rémi Métivier</i></p> <p>1.1 Photochromic Systems 1</p> <p>1.1.1 General Introduction 1</p> <p>1.1.2 Basic Principles 4</p> <p>1.1.3 Photochromic Molecules: Some History 5</p> <p>1.2 Organic Photochromic Molecules: Main Families 8</p> <p>1.2.1 Proton Transfer 9</p> <p>1.2.2 Trans–Cis Photoisomerization 12</p> <p>1.2.3 Homolytic Cleavage 13</p> <p>1.2.4 Cyclization Reaction 14</p> <p>1.2.4.1 Spiropyrans, Spirooxazines, and Chromenes 14</p> <p>1.2.4.2 Fulgides and Fulgimides 17</p> <p>1.2.4.3 Diarylethenes 18</p> <p>1.3 Molecular Design to Improve the Performance 20</p> <p>1.3.1 Figures of Merit 20</p> <p>1.3.2 Fatigue Resistance: Increasing the Number of Operating Cycles 21</p> <p>1.3.3 Bistability: Avoiding Unwanted Thermal Back-Reaction in the Dark 23</p> <p>1.3.3.1 Influence of Ethenic Bridge on theThermal Stability of the B Form 24</p> <p>1.3.3.2 Impact of the Heteroaryl Substituents on theThermal Stability of the B Form 24</p> <p>1.3.4 Fast Photochromic Systems: Reverting Back Spontaneously to the Colorless State in a Glance 25</p> <p>1.3.5 Gaining Efficiency of the Photoreaction: the Example of Diarylethenes 26</p> <p>1.4 Conclusion 31</p> <p>Irradiation at a Specific Wavelength: Isosbestic Point 32</p> <p>Case A: When the Thermal Back-Reaction is Negligible Compared to the Photochemical Reaction (Typically P-type) 33</p> <p>Case B: When the Thermal Back-Reaction is More Efficient than the Photochemical B→A Reaction (Typically Type) 34</p> <p>References 34</p> <p><b>2 Photochromic Transitional Metal Complexes for Photosensitization 47</b><br /><i>Chi-Chiu Ko and Vivian Wing-Wah Yam</i></p> <p>2.1 Introduction 47</p> <p>2.2 Photosensitization of Stilbene- and Azo-Containing Ligands 48</p> <p>2.3 Photosensitization of Spirooxazine-Containing Ligands 51</p> <p>2.4 Photosensitization of Diarylethene-Containing Ligands 54</p> <p>2.5 Photosensitization of Photochromic N∧C-Chelate Organoboranes 63</p> <p>2.6 Conclusion 65</p> <p>References 66</p> <p><b>3 Multi-addressable Photochromic Materials 71</b><br /><i>Shangjun Chen, Wenlong Li, and Weihong Zhu</i></p> <p>3.1 Molecular Logic Gates 71</p> <p>3.1.1 Two-Input Logic Gates 71</p> <p>3.1.2 Combinatorial Logic Systems 74</p> <p>3.1.2.1 Half-Adder and Half-Subtractor 74</p> <p>3.1.2.2 Keypad Locks 77</p> <p>3.1.2.3 Digital Encoder and Decoder 82</p> <p>3.2 Data Storage and Molecular Memory 84</p> <p>3.2.1 Fluorescence Spectroscopy 85</p> <p>3.2.2 Infrared Spectroscopy 90</p> <p>3.2.3 Optical Rotation 92</p> <p>3.3 Gated Photochromores 95</p> <p>3.3.1 Hydrogen Bonding 95</p> <p>3.3.2 Coordination 98</p> <p>3.3.3 Chemical Reaction 99</p> <p>References 105</p> <p><b>4 Photoswitchable Supramolecular Systems 109</b><br /><i>Guanglei Lv, Liang Chen, Haichuang Lan, and Tao Yi</i></p> <p>4.1 Introduction 109</p> <p>4.2 Photoreversible Amphiphilic Systems 110</p> <p>4.2.1 Photoreversible Diarylethene-Based Amphiphilic System 110</p> <p>4.2.2 Photoreversible Azobenzene-Based Amphiphilic System 116</p> <p>4.2.3 Photoreversible Spiropyran-Based Amphiphilic System 119</p> <p>4.3 Photoswitchable Host–Guest Systems 122</p> <p>4.3.1 Photocontrolled Supramolecular Self-Assembly 123</p> <p>4.3.2 Photocontrolled Capture and Release of Guest Molecules 128</p> <p>4.3.3 Fluorescent Switching Promoted by Host–Guest Interaction 133</p> <p>4.3.4 Photoswitchable Molecular Devices 137</p> <p>4.4 Photochromic Metal Complexes and Sensors 141</p> <p>4.4.1 Metal Complexes with Azobenzene Groups 141</p> <p>4.4.2 Metal Complexes with Diarylethene Groups 144</p> <p>4.4.3 Metal Complexes with Spirocyclic Groups 150</p> <p>4.4.4 Metal Complexes with Rhodamine 152</p> <p>4.5 Other Light-Modulated Supramolecular Interactions 153</p> <p>4.6 Conclusions and Outlook 159</p> <p>References 159</p> <p><b>5 Light-Gated Chemical Reactions and Catalytic Processes 167</b><br /><i>Robert Göstl, Antti Senf, and Stefan Hecht</i></p> <p>5.1 Introduction 167</p> <p>5.2 General Design Considerations 169</p> <p>5.3 Photoswitchable Stoichiometric Processes 171</p> <p>5.3.1 Starting Material Control 172</p> <p>5.3.2 Product Control 175</p> <p>5.3.3 Starting Material and Product Control 177</p> <p>5.3.4 Template Control 178</p> <p>5.4 Photoswitchable Catalytic Processes 182</p> <p>5.4.1 Activity Control 182</p> <p>5.4.2 Selectivity Control 185</p> <p>5.5 Outlook 187</p> <p>References 190</p> <p><b>6 Surface and Interfacial Photoswitches 195</b><br /><i>Junji Zhang and He Tian</i></p> <p>6.1 Photochromic SAMs 196</p> <p>6.1.1 Photochromic Electrode SAMs 196</p> <p>6.1.2 Photoreversible Functional Surfaces 198</p> <p>6.1.2.1 Photoswitchable Surface Wettability 198</p> <p>6.1.2.2 Photocontrolled Capture-and-Release System 202</p> <p>6.1.2.3 Smart Photochromic Surface Based on Supramolecular Systems 203</p> <p>6.1.2.4 Photochromic Surface for Molecular Data Processing 205</p> <p>6.2 Photoregulated Nanoparticles 206</p> <p>6.2.1 Photochromic Switches on Traditional Metal Nanoparticles 208</p> <p>6.2.1.1 Photoswitching on the Metal Nanoparticles 208</p> <p>6.2.1.2 Photoinduced Reversible Aggregation of Nanoparticles and Their Versatile Applications 210</p> <p>6.2.2 Photochromic Switches on Other Novel Functional Nanoparticles 215</p> <p>6.2.2.1 Photoswitchable Magnetic Nanoparticles 215</p> <p>6.2.2.2 Photomanipulated Quantum Dots 215</p> <p>6.2.2.3 Photochromic with Upconversion Nanoparticles 218</p> <p>6.2.3 Photocontrolled Mesoporous Silica Nanoparticles 220</p> <p>6.2.3.1 Photo-nanovalves 220</p> <p>6.2.3.2 Photo-nanoimpellers 223</p> <p>6.2.3.3 NIR Light-Triggered MSN Drug Delivery and Therapeutic Systems 224</p> <p>6.3 Photocontrolled Surface Conductance 226</p> <p>6.3.1 Photochromic Conductance Switching Based on SAMs 226</p> <p>6.3.2 Photochromic Conductance on Single-Molecule Level 228</p> <p>References 231</p> <p><b>7 Hybrid Organic/Photochromic Approaches to Generate Multifunctional Materials, Interfaces, and Devices 243</b><br /><i>Emanuele Orgiu and Paolo Samorì</i></p> <p>7.1 Introduction 243</p> <p>7.1.1 Tuning the Charge Injection in Organic-Based Devices by Means of Photochromic Molecules 245</p> <p>7.2 Tuning the Polaronic Transport in Organic Semiconductors by Means of Photochromic Molecules 251</p> <p>7.2.1 Photochromic Molecules and Organic Semiconductors Incorporated in Dyads, Multiads, and Polymers 251</p> <p>7.2.2 The Multilayer Approach 254</p> <p>7.2.3 The Blending Approach 255</p> <p>7.3 Photoresponsive Dielectric Interfaces and Bulk 262</p> <p>7.4 Conclusions and Future Outlooks 267</p> <p>Acknowledgments 268</p> <p>References 268</p> <p><b>8 Photochromic Bulk Materials 281</b><br /><i>Masakazu Morimoto, Seiya Kobatake, Masahiro Irie, Hari Krishna Bisoyi, Quan Li, Sheng Wang, and He Tian</i></p> <p>8.1 Photochromic Polymers 281</p> <p>8.1.1 Glass Transition Temperature 281</p> <p>8.1.2 Fluorescence 283</p> <p>8.1.3 Conductivity 287</p> <p>8.1.4 Living Radical Polymerization 288</p> <p>8.1.5 Surface Relief Grating 290</p> <p>8.1.6 Photomechanical Effect 290</p> <p>8.2 Single-Crystalline Photoswitches 293</p> <p>8.2.1 Crystalline-State Photochromic Materials 293</p> <p>8.2.2 Photochromic Diarylethene Single Crystals 293</p> <p>8.2.3 In situ X-ray Crystallographic Analysis of Photoisomerization Reaction 295</p> <p>8.2.4 Photoisomerization Quantum Yields 296</p> <p>8.2.5 Multicolor Photochromism of Multicomponent Crystals 297</p> <p>8.2.6 Nanoperiodic Structures Fabricated by Photochromic Reactions 299</p> <p>8.2.7 Photoinduced Shape Changes and Mechanical Performance 301</p> <p>8.3 Photochromic Liquid Crystals 305</p> <p>8.3.1 Introduction 305</p> <p>8.3.2 Spiropyran- and Spirooxazine-Based Photochromic Liquid Crystals 309</p> <p>8.3.3 Diarylethene-Based Photochromic Liquid Crystals 314</p> <p>8.3.4 Azobenzene-Based Photochromic Liquid Crystals 320</p> <p>8.3.5 Other Photochromic Liquid Crystals 327</p> <p>8.3.6 Conclusions and Outlook 328</p> <p>8.4 Photochromic Gels 329</p> <p>8.4.1 Introduction 329</p> <p>8.4.2 Azobenzene Gels 330</p> <p>8.4.3 Spiropyran and Spirooxazine Gels 335</p> <p>8.4.4 Diarylethenes Gels 337</p> <p>8.4.5 Naphthopyran Gels 342</p> <p>8.4.6 The Other Photochromic Gels 343</p> <p>8.4.7 Conclusion 346</p> <p>References 346</p> <p><b>9 Photochromic Materials in Biochemistry 361</b><br /><i>Danielle Wilson and Neil R. Branda</i></p> <p>9.1 Introduction 361</p> <p>9.2 Reversible Photochemical Switching of Biomaterial Function 362</p> <p>9.3 General Design Strategies and Considerations 362</p> <p>9.3.1 Photoswitchable Tethers 364</p> <p>9.3.1.1 The Incorporation Method 364</p> <p>9.3.1.2 Considerations 364</p> <p>9.3.2 Photoswitchable Small Molecules 365</p> <p>9.3.2.1 The Incorporation Method 365</p> <p>9.3.2.2 Considerations 365</p> <p>9.3.3 Chromophore Selection 367</p> <p>9.4 Selected Examples 367</p> <p>9.4.1 Photoswitchable Enzymes 367</p> <p>9.4.1.1 Drug-Inspired Small Molecule Inhibitors 367</p> <p>9.4.1.2 Phosphoribosyl Isomerase Inhibitor with Two Binding Units 370</p> <p>9.4.1.3 Direct Modification of Enzymes with Photochromic Groups 372</p> <p>9.4.2 Photoswitchable Peptides and Proteins 373</p> <p>9.4.2.1 Peptide Cross-Linking 373</p> <p>9.4.2.2 Cyclic Antimicrobial Peptide 375</p> <p>9.4.2.3 Genetically Encoded Amino Acids 376</p> <p>9.4.2.4 Control of Motor Protein Function Using Site-Selective Mutation 377</p> <p>9.4.3 Photoswitchable Ion Channels and Receptors 379</p> <p>9.4.3.1 Photocontrol of Channel Activation and Desensitization with a Tethered Glutamate 380</p> <p>9.4.3.2 Photocontrol of Insulin Release Using a Small Molecular Sulfonylurea 380</p> <p>9.4.3.3 Photocontrol of Receptors Using Red Light 381</p> <p>9.4.4 Photoswitchable Nucleotides 382</p> <p>9.4.4.1 Spiropyran-Modified Oligonucleotide Backbones 382</p> <p>9.4.4.2 Controlling RNA Duplex Hybridization with Light 384</p> <p>9.4.4.3 Diarylethene-Modified Oligonucleotides 385</p> <p>9.5 Summary 386</p> <p>References 386</p> <p><b>10 Industrial Applications and Perspectives 393</b><br /><i>Junji Zhang and He Tian</i></p> <p>10.1 Industrialization and Commercialization of Organic Photochromic Materials 393</p> <p>10.1.1 Commercialized T-type Photochromic Materials 395</p> <p>10.1.2 Commercialized P-Type Photochromic Materials 398</p> <p>10.2 Perspectives for Organic Photochromic Materials 399</p> <p>References 409</p> <p>Index 417</p>