Fluorescence reporter is the key element of any sensing or imaging technology. Its optimal choice and implementation is very important for increasing the sensitivity, precision, multiplexing power, and also the spectral, temporal, and spatial reso- tion in different methods of research and practical analysis. Therefore, design of ?uorescence reporters with advanced properties is one of the most important problems. In this volume, top experts in this ?eld provide advanced knowledge on the design and properties of ?uorescent dyes. Organic dyes were the ?rst ?uorescent materials used for analytical purposes, and we observe that they retain their leading positions against strong competition of new materials - conjugated polymers, semiconductor nanocrystals, and metal chelating complexes. Recently, molecular and cellular biology got a valuable tool of organic ?uorophores synt- sized by cell machinery and incorporated into green ?uorescent protein and its analogs. Demands of various ?uorescence techniques operating in spectral, anisotropy, and time domains require focused design of ?uorescence reporters well adapted to these techniques. Near-IR spectral range becomes more and more attractive for various applications, and new dyes emitting in this range are strongly requested. Two-photonic ?uorescence has become one of the major tools in bioimaging, and ?uorescence reporters well adapted to this technique are in urgent need. These problems cannot be solved without the knowledge of fundamental principles of dye design and of physical phenomena behind their ?uorescence response.

1;Advanced Fluorescence Reporters in Chemistry and Biology I;3 1.1;Fundamentals and Molecular Design;3 1.2;Series Editor;5 1.3;Aims and Scope;5 1.4;Preface;7 1.5;Contents;9 1.6;Part I: General Aspects;11 1.6.1;Comparative Analysis of Fluorescence Reporter Signals Based on Intensity, Anisotropy, Time-Resolution, and Wavelength-Ratiometry;12 1.6.1.1;1 Why Fluorescence?;13 1.6.1.2;2 Sensing Based on Emission Intensity;15 1.6.1.3;3 Variation of Emission Anisotropy;16 1.6.1.4;4 Time-Resolved and Time-Gated Detection;19 1.6.1.5;5 Wavelength Ratiometry with Two Emitters;20 1.6.1.5.1;5.1 Intensity Sensing with the Reference;21 1.6.1.5.2;5.2 Formation of Excimers;22 1.6.1.5.3;5.3 Förster Resonance Energy Transfer;23 1.6.1.6;6 Wavelength Ratiometry with Single Emitter;25 1.6.1.6.1;6.1 Transitions Between Ground-State Forms;26 1.6.1.6.2;6.2 Transitions Between Excited-State Forms;27 1.6.1.6.3;6.3 Multiparametric Reporters Combining the Transitions Between Ground-State and Excited-State Forms;28 1.6.1.7;7 Concluding Remarks;29 1.6.1.8;References;30 1.7;Part II: Design of Organic Dyes;34 1.7.1;Optimized UV/Visible Fluorescent Markers;35 1.7.1.1;1 Introduction;36 1.7.1.2;2 Coumarin Markers;36 1.7.1.3;3 Benzoxadiazole, Acridone, and Acridine Markers;42 1.7.1.4;4 Polyaromatic Markers;46 1.7.1.5;5 Fluorescein Markers;51 1.7.1.6;6 Rhodamine Markers;57 1.7.1.7;7 Concluding Remarks;62 1.7.1.8;References;63 1.7.2;Long-Wavelength Probes and Labels Based on Cyanines and Squaraines;73 1.7.2.1;1 Introduction;74 1.7.2.2;2 Cyanines: Fluorescent Labels for Low- and High-Molecular-Weight Analytes;75 1.7.2.3;3 Oxo-Squaraines: Microenvironment-Sensitive Dyes;80 1.7.2.3.1;3.1 Oxo-Squaraine Probes;83 1.7.2.3.1.1;3.1.1 Probes for Cellular Imaging, Proteins, and Other High-Molecular-Weight Analytes;83 1.7.2.3.1.2;3.1.2 Metal Cation Chemosensors;89 1.7.2.3.1.3;3.1.3 Chemosensor for Carbohydrates;91 1.7.2.3.1.4;3.1.4 pH Sensor;91 1.7.2.3.1.5;3.1.5 Chemosensors for Thiols;92 1.7.2.3.2;3.2 Oxo-Squaraine Labels;93 1.7.2.4;4 Ring-Substituted Squaraines: Probes and Labels with High Sensitivity and Photostability;95 1.7.2.4.1;4.1 Probes;96 1.7.2.4.2;4.2 Labels;101 1.7.2.5;5 Fluorescence Lifetime Dyes;103 1.7.2.6;6 Norcyanines and Norsquaraines: pH-Sensitive Probes and Labels;104 1.7.2.7;7 Concluding Remarks;106 1.7.2.8;References;107 1.7.3;Two-Photon Absorption in Near-IR Conjugated Molecules: Design Strategy and Structure-Property Relations;113 1.7.3.1;1 Introduction;114 1.7.3.1.1;1.1 Brief Historical Account of Two-Photon Absorption and pi-Conjugated Systems;115 1.7.3.1.2;1.2 Nonlinear Mechanisms in pi-Conjugated Molecules;116 1.7.3.1.2.1;1.2.1 Two-Photon Absorption;116 1.7.3.1.2.2;1.2.2 Excited State Absorption (ESA);120 1.7.3.1.2.3;1.2.3 Excited State Absorption via Two-Photon Absorption;122 1.7.3.1.3;1.3 Linear pi-Conjugated Molecular Systems;122 1.7.3.2;2 Experimental Methodologies for Linear and Nonlinear Optical Characterization;124 1.7.3.2.1;2.1 Linear Optical Characterization;124 1.7.3.2.2;2.2 Nonlinear Optical Characterization;127 1.7.3.2.2.1;2.2.1 Pump-Probe Technique;127 1.7.3.2.2.2;2.2.2 Z-Scan Technique;129 1.7.3.2.2.3;2.2.3 Two-Photon Fluorescence (2PF) Technique;131 1.7.3.3;3 Trends in Dye Design and Structure-Property Relations;134 1.7.3.3.1;3.1 Extending Absorption into the NIR;134 1.7.3.3.2;3.2 Symmetrical pi-Conjugated Cyanine-Like Systems;139 1.7.3.3.2.1;3.2.1 Cationic D-pi-D Dyes;139 1.7.3.3.2.2;3.2.2 Neutral D-pi-A-pi-D Dyes;140 1.7.3.3.2.3;3.2.3 Anionic A-pi-A Dyes;141 1.7.3.3.3;3.3 Asymmetrical pi-Conjugated Cyanine-Like Systems;143 1.7.3.3.4;3.4 Enhancement of 2PA Cross Sections;148 1.7.3.4;4 Conclusions and Future Directions;149 1.7.3.5;References;150 1.7.4;Discovery of New Fluorescent Dyes: Targeted Synthesis or Combinatorial Approach?;156 1.7.4.1;1 Introduction;157 1.7.4.2;2 Coumarin Dyes;157 1.7.4.2.1;2.1 Coumarin-Based Targeted Approach;158 1.7.4.2.2;2.2 Coumarin-Based Combinatorial Approach;160 1.7.4.3;3 Xanthene Dyes;163 1.7.4.3.1;3.