Principles and Applications of Photochemistry

Principles and Applications of Photochemistry......Page 2
Contents......Page 10
Preface......Page 16
AIMS AND OBJECTIVES......Page 18
1.1 THE QUANTUM NATURE OF MATTER AND LIGHT......Page 19
1.2 MODELLING ATOMS: ATOMIC ORBITALS......Page 23
1.3 MODELLING MOLECULES: MOLECULAR ORBITALS......Page 26
1.4 MODELLING MOLECULES: ELECTRONIC STATES......Page 30
1.5 LIGHT SOURCES USED IN PHOTOCHEMISTRY......Page 33
1.5.1 The Mercury Lamp......Page 34
1.5.2 Lasers......Page 35
1.6.1 Primary Quantum Yield (φ)......Page 42
1.6.2 Overall Quantum Yield (φ)......Page 43
2.1 INTRODUCTION......Page 46
2.2 THE BEER–LAMBERT LAW......Page 47
2.3 THE PHYSICAL BASIS OF LIGHT ABSORPTION BY MOLECULES......Page 49
2.4 ABSORPTION OF LIGHT BY ORGANIC MOLECULES......Page 52
2.5 LINEARLY-CONJUGATED MOLECULES......Page 56
2.6 SOME SELECTION RULES......Page 59
2.7 ABSORPTION OF LIGHT BY INORGANIC COMPLEXES......Page 60
3.1 INTRODUCTION......Page 64
3.2 JABLONSKI DIAGRAMS......Page 66
3.2.2 Internal Conversion......Page 68
3.2.5 Phosphorescence......Page 69
3.3.1 Excited Singlet-state Lifetime......Page 70
3.3.2 Excited Singlet-state Radiative Lifetime......Page 72
3.3.3 Lifetimes of the T1 Excited State......Page 74
AIMS AND OBJECTIVES......Page 76
4.1 INTRODUCTION......Page 77
4.2 FLUORESCENCE AND FLUORESCENCE SPECTRA......Page 78
4.3 AN EXCEPTION TO KASHA’S RULE......Page 80
4.4 FLUORESCENCE QUANTUM YIELD......Page 81
4.5.1 The Nature of S1......Page 82
4.5.4 The Heavy Atom Effect......Page 83
4.6 MOLECULAR FLUORESCENCE IN ANALYTICAL CHEMISTRY......Page 84
4.7 PHOSPHORESCENCE......Page 87
4.8.2 E-type Delayed Fluorescence (Thermally-activated Delayed Fluorescence)......Page 90
4.9 LANTHANIDE LUMINESCENCE......Page 91
5.1 INTRODUCTION......Page 94
5.3 THE FRANCK–CONDON FACTOR......Page 96
5.3.2 Case (B): Both Electronic States Have a Similar Geometry, with a Small Energy Separation between the States......Page 97
5.3.3 Case (C): The Electronic States Have Different Geometries, with a Large Energy Separation between the States......Page 98
5.4 HEAVY ATOM EFFECTS ON INTERSYSTEM CROSSING......Page 99
5.5 EL-SAYED’S SELECTION RULES FOR INTERSYSTEM CROSSING......Page 100
AIMS AND OBJECTIVES......Page 104
6.1 QUENCHING PROCESSES......Page 105
6.2 EXCIMERS......Page 107
6.3 EXCIPLEXES......Page 110
6.3.1 Exciplex Fluorescence Imaging......Page 112
6.4 INTERMOLECULAR ELECTRONIC ENERGY TRANSFER......Page 113
6.5 THE TRIVIAL OR RADIATIVE MECHANISM OF ENERGY TRANSFER......Page 114
6.6 LONG-RANGE DIPOLE–DIPOLE (COULOMBIC) ENERGY TRANSFER......Page 115
6.6.1 Dynamic Processes within Living Cells......Page 118
6.6.2 Molecular Ruler......Page 119
6.6.3 Molecular Beacons......Page 120
6.7 SHORT-RANGE ELECTRON-EXCHANGE ENERGY TRANSFER......Page 122
6.7.1 Triplet–Triplet Energy Transfer and Photosensitisation......Page 123
6.7.2 Singlet Oxygen and Photodynamic Therapy for Cancer Treatment......Page 125
6.8 PHOTOINDUCED ELECTRON TRANSFER (PET)......Page 127
6.8.1 Fluorescence Switching by PET......Page 128
6.8.2 The Marcus Theory of Electron Transfer......Page 129
6.8.3 Experimental Evidence Relating to the Marcus Equation......Page 131
6.8.4 Evidence for the Inverted Region......Page 134
AIMS AND OBJECTIVES......Page 136
7.1 THE PATHWAY OF PHOTOCHEMICAL REACTIONS......Page 137
7.2 DIFFERENCES BETWEEN PHOTOCHEMICAL AND THERMAL REACTIONS......Page 141
7.3 PHOTOLYSIS......Page 144
7.3.1 Photohalogenation of Hydrocarbons......Page 145
7.3.2 The Stratospheric Ozone Layer: Its Photochemical Formation and Degradation......Page 146
7.3.3 Radicals in the Polluted Troposphere......Page 149
7.4 AN INTRODUCTION TO THE CHEMISTRY OF CARBON-CENTRED RADICALS......Page 150
7.5.1 The Photochemistry of Metal Complexes......Page 152
7.5.2 An Aside: Redox Potentials Involved in Photoredox Reactions......Page 157
7.5.3 Organometallic Photochemistry......Page 158
AIMS AND OBJECTIVES......Page 162
8.1 EXCITED STATES OF ALKENES......Page 163
8.2 GEOMETRICAL ISOMERISATION BY DIRECT IRRADIATION OF C=C COMPOUNDS......Page 164
8.2.2 Vision......Page 165
8.3 PHOTOSENSITISED GEOMETRICAL ISOMERISATION OF C=C COMPOUNDS......Page 166
8.3.1 Synthesis......Page 167
8.4 CONCERTED PHOTOREACTIONS......Page 168
8.4.1 Electrocyclic Reactions......Page 169
8.4.2 Sigmatropic Shifts......Page 172
8.5 PHOTOCYCLOADDITION REACTIONS......Page 174
8.5.1 Solar Energy Storage......Page 175
8.6.1 DNA Damage by UV......Page 176
AIMS AND OBJECTIVES......Page 178
9.1 EXCITED STATES OF CARBONYL COMPOUNDS......Page 179
9.2 α-CLEAVAGE REACTIONS......Page 180
9.3 INTERMOLECULAR HYDROGEN-ABSTRACTION REACTIONS......Page 183
9.4 INTRAMOLECULAR HYDROGEN-ABSTRACTION REACTIONS......Page 184
9.5 PHOTOCYCLOADDITION REACTIONS......Page 185
9.6 THE ROLE OF CARBONYL COMPOUNDS IN POLYMER CHEMISTRY......Page 186
9.6.2 Photochemical Cross-linking of Polymers......Page 187
9.6.3 Photodegradation of Polymers......Page 189
AIMS AND OBJECTIVES......Page 190
10.2 INFORMATION FROM ELECTRONIC SPECTRA......Page 191
10.3 TRIPLET-QUENCHING STUDIES......Page 193
10.4 SENSITISATION......Page 197
10.5 FLASH PHOTOLYSIS STUDIES......Page 199
10.5.1 An Aside: Some Basic Ideas on Reaction Kinetics......Page 203
10.5.2 Flash Photolysis Studies in Bimolecular Electron-transfer Processes......Page 204
10.5.3 Photochemistry of Substituted Benzoquinones in Ethanol/Water......Page 207
10.5.4 Time-resolved Infrared Spectroscopy......Page 209
10.5.5 Femtochemistry......Page 210
10.6 LOW-TEMPERATURE STUDIES......Page 212
FURTHER READING......Page 213
AIMS AND OBJECTIVES......Page 214
11.1 INTRODUCTION TO SEMICONDUCTOR PHOTOCHEMISTRY......Page 215
11.2 SOLAR-ENERGY CONVERSION BY PHOTOVOLTAIC CELLS......Page 216
11.2.1 Dye-sensitised Photovoltaic Cells......Page 218
11.3 SEMICONDUCTORS AS SENSITISERS FOR WATER SPLITTING......Page 221
11.4 SEMICONDUCTOR PHOTOCATALYSIS......Page 225
11.5 SEMICONDUCTOR-PHOTOINDUCED SUPERHYDROPHILICITY......Page 228
FURTHER READING......Page 229
AIMS AND OBJECTIVES......Page 230
12.1 SOME BASIC IDEAS......Page 231
12.2.1 Micelles......Page 232
12.2.2 Zeolites as Supramolecular Hosts for Photochemical Transformations......Page 234
12.2.3 Cyclodextrins as Supramolecular Hosts......Page 237
12.3.1 Vision......Page 238
12.3.2 Photosynthesis......Page 239
12.3.3 Bacterial Photosynthesis......Page 244
12.4 ARTIFICIAL PHOTOSYNTHESIS......Page 246
12.5.1 Devices for Photoinduced Energy or Electron Transfer......Page 250
12.5.2 Devices for Information Processing based on Photochemical or Photophysical Processes......Page 251
12.5.3 Devices Designed to Undergo Extensive Conformational Changes on Photoexcitation: Photochemically-driven Molecular Machines......Page 252
FURTHER READING......Page 255
Index......Page 258