Luminescence of Lanthanide Ions in Coordination Compounds and Nanomaterials

This comprehensive book presents the theoretical principles, current applications and latest research developments in the field of luminescent lanthanide complexes; a rapidly developing area of research which is attracting increasing interest amongst the scientific community.

Luminescence of Lanthanide Ions in Coordination Compounds and Nanomaterials begins with an introduction to the basic theoretical and practical aspects of lanthanide ion luminescence, and the spectroscopic techniques used to evaluate the efficiency of luminescence. Subsequent chapters introduce a variety of different applications including:

? Circularly polarized luminescence
? Luminescence bioimaging with lanthanide complexes
? Two-photon absorption of lanthanide complexes
? Chemosensors
? Upconversion luminescence
? Excitation spectroscopy
? Heterometallic complexes containing lanthanides

Each chapter presents a detailed introduction to the application, followed by a description of experimental techniques specific to the area and an extensive review of recent literature.

This book is a valuable introduction to the literature for scientists new to the field, as well as providing the more experienced researcher with a comprehensive resource covering the most relevant information in the field; a ?one stop shop? for all key references.

List of Contributors xi

Preface xiii

1 Introduction to Lanthanide Ion Luminescence 1
Ana de Bettencourt-Dias

1.1 History of Lanthanide Ion Luminescence 1

1.2 Electronic Configuration of the +III Oxidation State 2

1.2.1 The 4f Orbitals 2

1.2.2 Energy Level Term Symbols 2

1.3 The Nature of the f-f Transitions 5

1.3.1 Hamiltonian in Central Field Approximation and Coulomb Interactions 5

1.3.2 Spin–Orbit Coupling 10

1.3.3 Crystal Field or Stark Effects 13

1.3.4 The Crystal Field Parameters Bkq and Symmetry 14

1.3.5 Energies of Crystal Field Split Terms 18

1.3.6 Zeeman Effect 19

1.3.7 Point Charge Electrostatic Model 21

1.3.8 Other Methods to Estimate Crystal Field Parameters 25

1.3.9 Allowed and Forbidden f-f Transitions 27

1.3.10 Induced Electric Dipole Transitions and Their Intensity – Judd–Ofelt Theory 34

1.3.11 Transition Probabilities and Branching Ratios 37

1.3.12 Hypersensitive Transitions 38

1.3.13 Emission Efficiency and Rate Constants 39

1.4 Sensitisation Mechanism 40

1.4.1 The Antenna Effect 40

1.4.2 Non-Radiative Quenching 44

2 Spectroscopic Techniques and Instrumentation 49
David E. Morris and Ana de Bettencourt-Dias

2.1 Introduction 49

2.2 Instrumentation in Luminescence Spectroscopy 52

2.2.1 Challenges in Design and Interpretation of Lanthanide Luminescence Experiments 52

2.2.2 Common Luminescence Experiments 57

2.2.3 Basic Design Elements and Configurations in Luminescence Spectrometers 61

2.2.4 Luminescence Spectrometer Components and Characteristics 63

2.2.5 Recent Advances in Luminescence Instrumentation 67

2.3 Measurement of Quantum Yields of Luminescence in the Solid State and in Solution 69

2.3.1 Measurement Against a Standard in Solution 70

2.3.2 Measurement Against a Standard in the Solid State 71

2.3.3 Absolute Measurement with an Integrating Sphere 72

2.4 Excited State Lifetimes 73

2.4.1 Number of Coordinated Solvent Molecules 73

3 Circularly Polarised Luminescence 77
Gilles Muller

3.1 Introduction 77

3.1.1 General Aspects: Molecular Chirality 77

3.1.2 Chiroptical Tools: from CD to CPL Spectroscopy 78

3.2 Theoretical Principles 79

3.2.1 General Theory 79

3.2.2 CPL Intensity Calculations, Selection Rules, Luminescence Selectivity, and Spectra–Structure Relationship 82

3.3 CPL Measurements 84

3.3.1 Instrumentation 84

3.3.2 Calibration and Standards 88

3.3.3 Artifacts in CPL Measurements 90

3.3.4 Proposed Instrumental Improvements to Record Eu(III)-Based CPL Signals 91

3.4 Survey of CPL Applications 93

3.4.1 Ln(III)-Containing Systems 93

3.4.2 Ln(III) Complexes with Achiral Ligands 94

3.4.3 Ln(III) Complexes with Chiral Ligands 99

3.5 Chiral Ln(III) Complexes to Probe Biologically Relevant Systems 109

3.5.1 Sensing through Coordination to the Metal Centre 109

3.5.2 Sensing through Coordination to the Antenna/Receptor Groups 112

3.6 Concluding Remarks 114

4 Luminescence Bioimaging with Lanthanide Complexes 125
Jean-Claude G. Bünzli

4.1 Introduction 125

4.2 Luminescence Microscopy 127

4.2.1 Classical Optical Microscopy: a Short Survey 127

4.2.2 Principle of Luminescence Microscopy 128

4.2.3 Principle of Time-resolved Luminescence Microscopy 131

4.2.4 Early Instrumental Developments for Time-resolved Microscopy with LLBs 134

4.2.5 Optimisation of Time-resolved Microscopy Instrumentation 140

4.2.6 Commercial Instruments 143

4.3 Bioimaging with Lanthanide Luminescent Probes and Bioprobes 144

4.3.1 b-Diketonate Probes 144

4.3.2 Aliphatic Polyaminocarboxylate and Carboxylate Probes 154

4.3.3 Macrocyclic Probes 163

4.3.4 Self-assembled Triple Helical Bioprobes 171

4.3.5 Other Bioprobes 177

4.4 Conclusions and Perspectives 180

5 Two-photon Absorption of Lanthanide Complexes: from Fundamental Aspects to Biphotonic Imaging Applications 197
Anthony D'Aleo, Chantal Andraud and Olivier Maury

5.1 Introduction 197

5.2 Two-photon Absorption, a Third Nonlinear Optical Phenomenon 198

5.2.1 Theoretical and Historical Background 198

5.2.2 Experimental Determination of the 2PA Efficiency of Molecules 199

5.2.3 Two-photon Fluorescence Microscopy for Biological Imaging 200

5.2.4 Molecular Engineering for Multiphonic Imaging 201

5.3 Spectroscopic Evidence for the Two-photon Sensitisation of Lanthanide Luminescence 205

5.3.1 1961: The Breakthrough Experiments 205

5.3.2 Two-photon Excitation of f-f Transitions 206

5.3.3 The Two-photon Antenna Effect 207

5.3.4 The Charge Transfer State Mediated Sensitisation Process 209

5.3.5 Optimising Molecular Two-photon Cross Section: the Brightness Trade-off 211

5.3.6 Two-photon Excited Luminescence in Solid Matrix 214

5.3.7 Two-photon Time-gated Spectroscopy 214

5.4 Towards Biphotonic Microscopy Imaging 215

5.4.1 Proof of Concept 215

5.4.2 Towards the Design of an Optimised Bio-probe 217

5.4.3 Design of Lanthanide containing Nano-probes, toward Single-object Imaging 222

5.4.4 Towards NIR-to-NIR Imaging 223

5.5 Conclusions 225

6 Lanthanide Ion Complexes as Chemosensors 231
Thorfinnur Gunnlaugsson and Simon J. A. Pope

6.1 Photophysical Properties of LnIII Based Sensors 231

6.1.1 Emission Based Sensors 231

6.1.2 Luminescence Lifetime 232

6.1.3 Spectral Form, Hypersensitivity and Ratiometric Peaks 233

6.2 Sensor Design Principles 233

6.2.1 The Design of Ln-receptor Sites and Antenna Components 234

6.2.2 Covalent versus Self-assembled Ln-receptor Design 235

6.2.3 Sensors for Cations 237

6.2.4 Sensors for Anions 249

6.3 Interactions with DNA and Biological Systems 260

7 Upconversion of Ln3+ -based Nanoparticles for Optical Bio-imaging 269
Frank C.J.M. van Veggel

7.1 Introduction 269

7.2 Physical Properties of Ln3+ Ions 272

7.3 Basic Principles of Upconversion 272

7.4 Synthesis of Core and Core–Shell Nanoparticles 277

7.4.1 Syntheses in Organic Solvent 277

7.4.2 Syntheses in Aqueous Media 277

7.4.3 Surface Modification 278

7.5 Characterisation 278

7.5.1 Basic Techniques 278

7.5.2 Advanced Techniques 279

7.6 Bio-imaging 283

7.6.1 Basics 283

7.6.2 Cell Studies 283

7.6.3 Animal Studies 287

7.6.4 Discussion 290

7.7 Upconversion and Magnetic Resonance Imaging 293

7.8 Conclusions and Outlook 295

8 Direct Excitation Ln(III) Luminescence Spectroscopy to Probe the Coordination Sphere of Ln(III) Catalysts, Optical Sensors and MRI Agents 303
Janet R. Morrow and Sarina J. Dorazio

8.1 Introduction 303

8.1.1 Luminescence Spectroscopy for Defining the Ln(III) Coordination Sphere 303

8.2 Direct Excitation Lanthanide Luminescence 304

8.2.1 Luminescence Properties of the Lanthanide Ions 304

8.2.2 Ln(III) Excitation Spectroscopy 306

8.2.3 Ln(III) Emission Spectroscopy 307

8.2.4 Time-Resolved Ln(III) Luminescence Spectroscopy 308

8.2.5 Luminescence Resonance Energy Transfer 310

8.3 Defining the Ln(III) Ion Coordination Sphere through Direct Eu(III) Excitation Luminescence Spectroscopy 311

8.3.1 Eu(III) Complex Speciation in Solution: Number of Excitation Peaks 311

8.3.2 Excitation Spectra of Geometric Isomers 311

8.3.3 Innersphere Coordination of Anions 312

8.3.4 Ligand Ionisation 314

8.4 Luminescence Studies of Anion Binding in Catalysis and Sensing 317

8.4.1 Phosphate Ester Binding and Cleavage 317

8.4.2 Sensing Biologically Relevant Anions 318

8.5 Luminescence Studies of Ln(III) MRI Contrast Agents 320

8.5.1 Types of Ln(III) MRI Contrast Agents 320

8.5.2 Luminescence Studies of Ln(III) ParaCEST Agents 322

8.6 Conclusions 326

9 Heterometallic Complexes Containing Lanthanides 331
Stephen Faulkner and Manuel Tropiano

9.1 Introduction 331

9.2 Properties of a Heteromultimetallic Complex 332

9.3 Lanthanide Assemblies in the Solid State 335

9.4 Lanthanide Assemblies in Solution 338

9.4.1 Lanthanide Helicates 338

9.4.2 Non-helicate Structures 341

9.5 Heterometallic Complexes Derived from Bridging and Multi-compartmental Ligands 342

9.6 Energy Transfer in Assembled Systems 347

9.7 Responsive Multimetallic Systems 351

9.8 Summary and Prospects 353

References 353

Index 359

Professor Ana de Bettencourt-Dias, University of Nevada, Inorganic and Materials Chemistry
Professor de Bettencourt-Dias' research interests lie in the development of new ligands (particularly organic and transition metal complexes) for highly emissive lanthanide ion complexes. She first became active in the field of the luminescent lanthanide ions in 2001 when she took her first academic position at Sycrause University, and her publications in this area include two well-received review articles which have been cited over 80 times. Professor de Bettencourt-Dias co-organised a symposium on 'Luminescence and Magnetism of Lanthanide-Containing Materials' at the ACS 2010 Fall Meeting, and she is program chair for the 2011 Rare Earth Research Conference.
In addition to her research, Professor de Bettencourt-Dias currently teaches classes in Advanced Inorganic Chemistry and Chemistry of the Less Common Elements.