List of Contributors xv
Preface to Handbook of Aggregation-Induced Emission xxi
Preface to Volume 1: Fundamentals xxiii
1 The Mechanistic Understanding of the Importance of Molecular Motions to Aggregation-induced Emission 1
Junkai Liu and Ben Zhong Tang
1.1 Introduction 1
1.2 Restriction of Intramolecular Motion 2
1.2.1 Restriction of Intramolecular Rotation 3
1.2.2 Restriction of Intramolecular Vibration 4
1.2.3 Ultrafast Insights into Tetraphenylethylene Derivatives 6
1.2.4 Theoretical Insights into Restriction of Intramolecular Motion 8
1.3 Restricted Access to Conical Intersection 12
1.4 Restriction of Access to the Dark State 14
1.5 Suppression of Kasha's Rule 15
1.6 Through Space Conjugation 17
1.6.1 Clusterization-Triggered Emission 18
1.6.2 Polymerization-induced Emission 19
1.6.3 Excited-state Through-space Conjugation 19
1.7 Perspective 21
References 23
2 Understanding the AIE Mechanism at the Molecular Level 27
Xiaoyan Zheng and Qian Peng
2.1 Introduction 27
2.2 Theoretical Methods 28
2.2.1 Radiative and Nonradiative Rate Constants 28
2.2.2 Computational Details 29
2.3 Revealed AIE Mechanism 31
2.3.1 Rotating Vibrations of Intramolecular Aromatic Ring 31
2.3.2 Stretching Vibrations of Bonds 33
2.3.3 Bending Vibration of Bonds 34
2.3.4 Flipping Vibrations of Molecular Skeletons 35
2.3.5 Twisting Vibration of Molecular Skeletons 36
2.4 Visualize Calculated Parameters in Experiments 37
2.4.1 Stokes Shift vs Reorganization Energy 37
2.4.2 Resonance Raman Spectroscopy (RSS) vs Reorganization Energy 38
2.4.3 Isotope Effect vs DRE 40
2.4.4 Linear Relationship between Fluorescence Intensity and Amorphous Aggregate Size 42
2.4.5 Pressure-induced Enhanced Emission (PIEE) 44
2.5 Molecular Design Based on AIE Mechanism 45
2.6 Summary and Outlook 46
Acknowledgments 48
References 48
3 Aggregation-induced Emission from the Restriction of Double Bond Rotation at the Excited State 55
Ming Hu and Yan-Song Zheng
3.1 Introduction 55
3.2 AIE Phenomena and Applications from RDBR Mechanism 58
3.2.1 Evolvement and Development of AIE Mechanisms 58
3.2.2 Investigation of RDBR AIE Mechanism by E/Z isomerization 64
3.2.3 Investigating of RDBR AIE Mechanism by Immobilization of TPE Propeller-like Conformation 69
3.2.4 Research of Theoretical Calculation on RDBR 78
3.2.5 Other AIEgens Involving RBDR Process 84
3.3 Conclusions 93
References 94
4 The Expansion of AIE Thought: From Single Molecule to Molecular Uniting 99
Qiuyan Liao, Qianqian Li, and Zhen Li
4.1 Aggregation-Induced Emission 99
4.2 Photoluminescence Materials Based on Molecular Set 101
4.3 Mechanoluminescence Materials Based on Molecular Set 106
4.3.1 Mechanoluminescence Materials with Fluorescence Emission 106
4.3.2 Mechanoluminescence Materials with Mechanical Induced Dual-or Tri-color Emission 115
4.3.3 Quantitative Research of Mechanoluminescence Property 121
4.4 Mechanochromism Materials 122
4.4.1 Mechanochromism Materials Based on Polymorphs 122
4.4.2 Mechanochromism Materials Based on Excimer Emission 125
4.4.3 Other Kinds of Mechanochromism Materials 128
4.5 Room Temperature Phosphorescence Materials Based on Molecular Uniting 131
4.5.1 Room Temperature Phosphorescence Materials with Aromatics 131
4.5.2 Room Temperature Phosphorescence Materials with Simple or Nonaromatic Structure 140
4.5.3 Room Temperature Phosphorescence Materials with Multiple Emission 142
4.5.4 Photoinduced Room Temperature Phosphorescence Materials 144
4.6 Conclusion and Perspectives 147
References 147
5 Clusterization-Triggered Emission 153
Haoke Zhang and Ben Zhong Tang
5.1 Introduction 153
5.2 Pure n-Electron Systems 156
5.3 Pure ¿-Electron Systems 160
5.4 (n, ¿)-Electrons Systems 164
5.5 Other Systems 166
5.6 Summary 167
References 168
6 Crystallization-induced Emission Enhancement 177
Yong Qiang Dong, Yingying Liu, Mengyang Liu, Qian Wang, and Kang Wang
6.1 Introduction 177
6.2 Tetraphenylethylene Derivatives 178
6.3 CIEE Active Luminogens with Bulky Conjugation Core 183
6.3.1 Dibenzofulvene (DBF) Derivatives (Chart 6.2) 183
6.3.2 9-([1,1¿-Biphenyl]-4-ylphenylmethylene)-9H-xanthene 185
6.3.3 Dicyanomethylenated Acridones 186
6.3.4 Bis(diarylmethylene)dihydroanthracene [31] 187
6.4 Other High-contrast CIEE Luminogens 190
6.4.1 4-Dimethylamino-2-Benzylidene Malonic Acid Dimethyl Ester 190
6.4.2 Diphenyl Maleimide Derivatives [33] 191
6.4.3 3,4-Bisthienylmaleic Anhydride [34] 192
6.4.4 Boron-containing CIEE Luminogens 193
6.5 Potential Applications 196
6.5.1 Volatile Organic Compounds (VOCs) Sensor 196
6.5.2 OLED 196
6.5.3 High-density Data Storage 197
6.5.4 Mechanochromic (MC) Luminescent Sensor 198
6.6 Summary and Perspective 198
References 198
7 Surface-fixation Induced Emission 203
Yohei Ishida and Shinsuke Takagi
7.1 Introduction 203
7.2 What Happened to the Characteristics of Molecules on the Clay Mineral Nanosheets 205
7.3 Clay-Molecular Complexes 206
7.4 Absorption Spectra of Clay-Molecular Complexes 207
7.5 Emission Enhancement Phenomenon in Clay-Molecular Complexes: S-FIE 208
7.6 Mechanism of Surface-Fixation Induced Emission 211
7.7 Summary and Outlook 214
Acknowledgment 215
References 215
8 Aggregation-induced Delayed Fluorescence 221
Yan Fu, Hao Chen, Zujin Zhao, and Ben Zhong Tang
8.1 Introduction 221
8.2 Novel Aggregation-induced Delayed Fluorescence Luminogens 222
8.3 Conclusion and Outlook 247
References 247
9 Homogeneous Systems to Induce Emission of AIEgens 251
Kenta Kokado and Kazuki Sada
9.1 Introduction 251
9.2 Homogeneous Solution 252
9.2.1 Complexation with Anions 253
9.2.2 Complexation with Cations 254
9.2.3 Inclusion Complexes 256
9.2.4 Adhesion on Macromolecules 257
9.2.5 Steric Hindrance 258
9.2.6 Covalent Linkage 259
9.3 Liquid 260
9.4 Gels and Network Polymers 261
9.4.1 Chemically Crosslinked Gels 261
9.4.2 Physically Crosslinked Gels 262
9.5 Crystalline Materials 264
9.6 Outlook and Future Perspectives 266
References 266
10 Hetero-aggregation-induced Tunable Emission (HAITE) Through Cocrystal Strategy 273
Yinjuan Huang and Qichun Zhang
10.1 Introduction 273
10.2 Interactions Within Organic Cocrystals 274
10.3 Preparation of Organic Cocrystals 275
10.4 Molecular Stacking Modes Within Organic Cocrystals 276
10.5 Characterization of Organic Cocrystals 277
10.6 HAITE Through Cocrystal Strategy 277
10.6.1 HAITE with Tunable Color and Enhanced Emission 278
10.6.1.1 Insignificant Changed Intensity but Tuned Color 278
10.6.1.2 Enhanced Emission and Tuned Color 287
10.6.2 HAITE with Increased PLQY but Intrinsic Color 291
10.6.3 HAITE: Thermally Activated Delayed Fluorescence 297
10.6.4 HAITE-phosphorescence 300
10.7 Summary and Outlook 302
References 304
11 Anti-Kasha Emission from Organic Aggregates 311
Wenbin Huang and Zikai He
11.1 Introduction 311
11.2 Anti-Kasha Emission from Aromatic Carbonyl Compounds in Aggregates 312
11.3 Anti-Kasha Emission from Azulene Compounds in Aggregate 322
11.4 Anti-Kasha Emission from Other Unconventional Aromatic Compounds in Aggregates 324
11.5 Conclusions 327
References 327
12 Aggregation-enhanced Emission: From Flexible to Rigid Cores 333
Harnimarta Deol, Gurpreet Singh, Vandana Bhalla, and Manoj Kumar
12.1 Introduction 333
12.2 Freely Moving Rotors-induced Emission Enhancement 334
12.3 Guest-induced Emission Enhancement 344
12.4 Conclusion 366
Acknowledgment 367
References 367
13 Room-temperature Phosphorescence of Pure Organics 371
Tianwen Zhu, Zihao Zhao, Tianjia Yang, and Wang Zhang Yuan
13.1 Introduction 371
13.2 Fundamental Mechanism in Organic Phosphorescence 372
13.2.1 Photophysical Process for Phosphorescence 372
13.2.2 Theoretical Study on Phosphorescent Process 373
13.3 Recent Progress in Organic RTP Materials 375
13.3.1 Crystallization-induced RTP 375
13.3.1.1 Heavy Atom Effect 376
13.3.1.2 Molecular Interaction 380
13.3.1.3 H-aggregation 380
13.3.2 Doping in Rigid Matrix-induced RTP 382
13.3.2.1 Host-Guest System 385
13.3.2.2 Doping in Polymer Matrix 387
13.3.3 Clustering-triggered RTP 389
13.3.3.1 Natural Products 389
13.3.3.2 Synthetic Compounds 394
13.3.4 Other Systems 399
13.3.4.1 Amorphous Organics 399
13.3.4.2 Organic Framework 399
13.3.4.3 Supramolecular Organics 402
13.3.4.4 Hybrid Perovskites 403
13.3.5 Applications 405
13.4 Conclusions and Perspectives 405
References 407
14 A Global Potential Energy Surface Approach to the Photophysics of AIEgens: The Role of Conical Intersections 411
Rachel Crespo-Otero and Lluís Blancafort
14.1 Introduction 411
14.2 Methodological Aspects 412
14.2.1 Intramolecular Restriction Models and the FGR-based Approach 412
14.2.2 A PES-based Description of Photochemical Mechanisms 412
14.2.3 Computational Approaches for Excited States 416
14.2.3.1 Electronic Structure Methods for Excited States 416
14.2.3.2 Dynamics Simulations in the Context of AIE 420
14.2.4 Methods for Large Systems 420
14.3 CI-centered Global PES for AIEgens 424
14.3.1 Double-bond Torsion 424
14.3.2 Double-bond Torsion vs Cyclization in TPE Derivatives 428
14.3.3 Excited-state Intramolecular Proton Transfer (ESIPT) Compounds 431
14.3.4 Ring Puckering 432
14.3.5 Bond Stretching 435
14.3.6 A View of AIE Based on the RACI Model and the Global PES 436
14.4 Crystallization-induced Phosphorescence 436
14.5 Effect of Intermolecular and Intramolecular Interactions on the Photophysics of AIEgens 437
14.5.1 Excitonic Effects in AIE 437
14.5.2 Effect of Intramolecular and Intermolecular Interactions on Emission Color 439
14.6 New Challenges 439
14.6.1 The Role of Dark States in AIE 439
14.6.2 Pressure-induced Emission Enhancement 440
14.6.3 AIE in Transition Metal (TM) Compounds 442
14.7 Conclusions and Outlook 443
References 444
15 Multicomponent Reactions as Synthetic Design Tools of AIE and Emission Solvatochromic Quinoxalines 455
Lukas Biesen and Thomas J. J. Müller
15.1 Introduction 455
15.2 Synthetic Approaches to Quinoxalines via Multicomponent Reactions and One-Pot Processes 456
15.3 Photophysical Properties and Emission Solvatochromicity of Quinoxalines 462
15.4 AIE Characteristics and Effects of Quinoxalines 468
15.5 Conclusion 476
Acknowledgments 476
References 476
16 Aggregation-induced Emission Luminogens with Both High-luminescence Efficiency and Charge Mobility 485
Ying Yu, Zheng Zhao, and Ben Zhong Tang
16.1 Introduction 485
16.2 p-Type OSCs 487
16.3 n-Type OSCs 495
16.4 Ambipolar OSCs 500
16.5 Conclusion and Perspective 505
References 505
17 Morphology Modulation of Aggregation-induced Emission: From Thermodynamic Self-assembly to Kinetic Controlling 509
Kaizhi Gu, Chenxu Yan, Zhiqian Guo, and Wei-Hong Zhu
17.1 Introduction 509
17.2 Aggregation Modulation of AIE Bioprobes via Hydrophilicity Improvement 511
17.2.1 Molecular Modification 511
17.2.2 Polymerization with Hydrophilic Matrix 515
17.3 Thermodynamic Self-assembly of AIE Materials 519
17.4 Morphology Tuning of AIE Nanoaggregates 519
17.5 Kinetic-driven Preparation of AIE NPs 523
17.6 Conclusion and Outlook 527
References 527
18 AIE-active Polymer 531
Rong Hu, Anjun Qin, and Ben Zhong Tang
18.1 Introduction 531
18.2 Photophysical Properties 532
18.2.1 Quantum Yield 532
18.2.2 Photosensitization 536
18.2.3 Two-photon Absorption and Emission 538
18.2.4 Circularly Polarized Luminescence 540
18.3 Applications 541
18.3.1 Chem-sensor 541
18.3.2 Bioimaging 543
18.3.3 Therapy Applications 546
18.4 Conclusion and Perspective 549
Acknowledgments 550
References 550
19 Liquid-crystalline AIEgens: Materials and Applications 555
Kyohei Hisano, Supattra Panthai, and Osamu Tsutsumi
19.1 Introduction 555
19.2 Materials: Molecular Design 556
19.2.1 Discotic LC AIEgen 556
19.2.2 Calamitic LC AIEgens 561
19.2.3 Polymeric LC AIEgens 566
19.3 Applications of LC AIEgens 567
19.3.1 Linearly Polarized Luminescence 567
19.3.2 Circularly Polarized Luminescence 568
19.4 Conclusion 571
References 571
20 Push-Pull AIEgens 575
Andrea Nitti and Dario Pasini
20.1 Introduction 575
20.2 Basic Concept of Molecular Design 576
20.2.1 Photophysical Excited States in Aggregates 576
20.2.2 Fundamental Molecular Design to Achieve Push-Pull AIEgens 579
20.3 Push-Pull AIEgens from Rotor Structure 581
20.3.1 Double Bond Stator 582
20.3.2 Point-restricted Rotors from Atoms or Functional Groups 584
20.3.3 Aromatic Rotors 587
20.4 Push-Pull AIEgens from ACQ Chromophores 589
20.4.1 BT-based AIEgens 589
20.4.2 Cyanine and DCM-based AIEgens 594
20.4.3 QM-based AIEgens 595
20.4.4 DPP-based AIEgens 597
20.4.5 Rylene-based AIEgens 599
20.5 Concluding Remarks 602
References 602
Index 609
