Optical Spectra of Phthalocyanines and Related Compounds (eBook)

A Guide for Beginners

Hiroaki Isago (Autor)

eBook Download: PDF

2015 | 2015
X, 132 Seiten
Springer Tokyo (Verlag)
978-4-431-55102-7 (ISBN)

Infos

This book displays how optical (absorption, emission, and magnetic circular dichroism) spectra of phthalocyanines and related macrocyclic dyes can be varied from their prototypical ones depending on conditions. As these compounds can be involved in colorful chemistry (which might be driven by impurities in solvents), their spectra behave like the sea-god Proteus in their mutability. Therefore, those who have been engaged with phthalocyanines for the first time, including even educated professional researchers and engineers, may have been embarrassed by the deceptive behavior of their compounds and could have, in the worst cases, given up their projects. This book is aimed not merely at reviewing the optical spectra, but also at helping such people, particularly beginners, to figure them out by showing some examples of their prototypical spectra and their variations in several situations. For the purpose of better understanding, the book also provides an introduction to their theoretical backgrounds as graphically as possible and without mathematicization for readers who are weak in mathematics.

Inhalt

Preface 6
Acknowledgments 8
Contents 9
1 Introduction 11
1.1 How Do We See a Color? 11
1.1.1 No Light, No Color 11
1.1.2 How to See a Color 12
1.1.3 Why Does a Molecule Absorb Light? 15
1.1.4 Electronic Transitions and Molecular Orbitals 17
1.2 Phthalocyanines as Functional Dyes 20
1.2.1 Traditional Dyes and Functional Dyes 20
1.2.2 What Are Phthalocyanines? 21
1.2.3 Use of Phthalocyanines in Industry 23
1.2.3.1 Application to Optical Data Storage 24
1.2.3.2 Application to Electronic Photograph 25
1.2.4 Application in Medical Fields 26
1.2.4.1 Photosensitization of Singlet Oxygen for Photodynamic Cancer Therapy 26
1.2.4.2 Fluorescence Imaging for Tumor Diagnosis 28
References 28
2 “Prototypical” Optical Absorption Spectra of Phthalocyanines and Their Theoretical Background 30
2.1 Prototypical Absorption Spectra of Phthalocyanines in Solutions 31
2.1.1 Prototypical Spectra of Phthalocyanines 31
2.1.2 Comparison with Spectra of Similar Tetrapyrrole Macrocycles 32
2.2 Molecular Orbital Models of Porphyrins and Phthalocyanines 34
2.2.1 Selection Rule in Optical Absorption (Optical Absorption = Generation of Vector) 34
2.2.2 Perimeter Model 35
2.2.3 Graphical Description of Molecular Orbitals 37
2.2.4 “Descent-in-Symmetry” Model 38
2.2.5 How to Use Character Tables (for Group Theory) 39
2.2.6 Gouterman’s “Four-Orbital” Model 41
2.2.7 Why Are the Spectra of Phthalocyanines Different from Those of Porphyrins in Spite of Their Similar Structures? 42
2.2.8 Degeneracy of Excited States and Magnetic Circular Dichroism (MCD) Spectroscopy 43
2.2.9 Assignment of Phthalocyanine Spectra by MCD Spectroscopy 46
2.2.10 Computational Molecular Orbital Calculations 48
References 48
3 Real Optical Absorption Spectra Observed in Laboratories 50
3.1 Are All Phthalocyanines Blue? 50
3.2 Factors Affecting Absorption Spectra of Phthalocyanines 52
3.2.1 Effects of Metal Ion(s) in the Cavity of the Macrocycle and Axial Ligands on the Metal 52
3.2.2 Effects of Peripheral Substituents 65
3.2.2.1 Electronic Effects 67
3.2.2.2 Steric Effects 70
3.2.3 Effects of Ring Expansion, Contraction, and Symmetry Lowering 70
3.2.3.1 Effects of Ring Expansion and Contraction 70
3.2.3.2 Effects of Symmetry Lowering 72
3.2.3.3 Accidental Degeneracy and Pseudo Faraday A-Term in MCD Spectrum 73
3.2.4 Interaction Between Chromophores 75
3.2.4.1 Spectral Changes Associated with Molecular Aggregation 75
3.2.4.2 Exciton Coupling of Nondegenerate Transitions 80
3.2.4.3 Cofacial Dimers of Phthalocyanine and Degeneracy of Their Transitions 81
3.2.4.4 J-Aggregation of Phthalocyanines and Degeneracy of Their Transitions 83
3.2.4.5 Oblique Dimer of Phthalocyanines 84
3.2.4.6 ?–? Interaction Between Macrocycles 85
3.2.5 Effects of Acid-Base Equilibria Involving Phthalocyanine Macrocycle 88
3.2.5.1 Metal-Free Phthalocyanines as Acids 88
3.2.5.2 Phthalocyanines as Multicentered Bases 89
3.2.6 Electron Transfer Reactions Involving Phthalocyanine Macrocycle 91
3.2.6.1 Absorption Spectra of Oxidized Phthalocyanines 91
3.2.6.2 Oxidized Double-Decker Phthalocyanines 94
3.2.6.3 Absorption Spectra of Reduced Phthalocyanines 96
3.2.7 Solvent Effects 98
3.2.7.1 Physical Interaction 98
3.2.7.2 Chemical Interaction 100
3.2.7.3 Other Effects 101
3.2.7.4 Effect of Impurities in Solvents 103
3.3 Spectra of Related Macrocyclic Compounds 105
3.3.1 Subphthalocyanines 105
3.3.2 Superphthalocyanines 105
3.3.3 Tetrabenzocorrolazines (Tetrabenzotriazacorroles) 107
3.4 Absorption Spectra in Solid State 108
References 109
4 Optical Emission Spectra of Phthalocyanines 116
4.1 Fluorescence: Optical Emission from the Lowest Singlet Excited States 116
4.1.1 How Does an Excited Molecule Emit Light? 116
4.1.2 Appearance of Fluorescence Spectra 119
4.1.3 Fluorescence Quantum Yield 122
4.1.3.1 How to Determine Quantum Yield 122
4.1.3.2 Effects of Central Metal Element 123
4.1.3.3 Effects of Peripheral Substituents 126
4.1.3.4 Fluorescence of Conjugate Acids of Phthalocyanines 127
4.1.3.5 Fluorescence of Related Macrocyclic Compounds 127
4.1.4 Effects of Interactions Between Fluorophores 128
4.1.5 Misleading Impurity Emission (Importance of Measuring the Excitation Spectra) 130
4.2 Other Emission Phenomena 132
4.2.1 Phosphorescence 132
4.2.2 Delayed Fluorescence (DF) 135
4.2.3 Emission at Approximately 1270 nm 137
4.2.4 Emission from Upper Excited States 137
4.2.5 Electrochemiluminescence (or Electrogenerated Chemiluminescence ECL)
References 140

Produkt-Details

• Erscheint lt. Verlag: 18.5.2015
• Reihe/Serie: NIMS Monographs
• Reihe/Serie: NIMS Monographs
• Zusatzinfo: X, 132 p. 79 illus., 41 illus. in color.
• Verlagsort: Tokyo
• Sprache: englisch
• Themenwelt: Naturwissenschaften ► Chemie ► Physikalische Chemie
• Themenwelt: Naturwissenschaften ► Physik / Astronomie
• Themenwelt: Technik ► Maschinenbau
• Schlagworte: Absorption Spectra of Phthalocyanines • Emission Spectra of Phthalocyanines • Functional Dyes • Gouterman Four Orbital Model • molecular aggregation • phthalocyanines • Spectra of Porphyrins
• ISBN-10: 4-431-55102-6 / 4431551026
• ISBN-13: 978-4-431-55102-7 / 9784431551027