Covering the gap between basic textbooks and over-specialized scientific publications, this is the first reference available to describe this interdisciplinary topic for PhD students and scientists starting in the field. The result is an introductory description providing suitable practical examples of the basic methods used to study tautomeric processes, as well as the theories describing the tautomerism and proton transfer phenomena. It also includes different spectroscopic methods for examining tautomerism, such as UV-VIs, time-resolved fluorescence spectroscopy, and NMR spectroscopy, plus the theoretical and practical background information. With its excellent overview of the methods, theories and examples, this is the perfect guide for any scientist dealing with tautomeric compounds in a wider context.
Liudmil Antonov is a Professor of Analytical and Physical Organic Chemistry at Bulgarian Academy of Sciences. Having obtained MSc (1989) and PhD (1994) degree from University of Sofia, he spent 1 year at Tokyo Institute of Technology before taking an appointment at University of Forestry (UF) in Sofia. In 1998 he was appointed as youngest in Bulgaria Associated Professor in Analytical Chemistry and from 1999 to 2002 headed the Department of Chemistry UF. After stays at AIST (Japan, 2002, 2006) as JSPS Fellow and at Humboldt University of Berlin (2003-2004) as Alexander von Humboldt Fellow and work for European Commission as reviewer and panel member (Directorate General for Research, 2001-2005) he joined Bulgarian Academy of Sciences in 2007. He has authored 83 research papers in the fields of tautomerism, dye chemistry, new materials, chemometrics, and instrumental analysis, cited over 1200 times.
Preface TAUTOMERISM: INTRODUCTIN, HISTORY, AND RECENT DEVELOPMENTS IN EXPERIMENTAL AND THEORETICAL METHODS The Definition and Scope of Tautomerism: Principles and Practicalities Causes of Reversal in Tautomeric Form: Aromatic Resonance Causes of Reversal in Tautomeric Form: Lone-Pair and Dipolar Repulsion Causes of Reversal in Tautomeric Form: Selective Stabilization Through "Far" Intramolecular Hydrogen Bonding Changes in Tautomeric Form Brought About by Electronegative Substituents The Influence of Solvent on Tautomeric Form Tautomeric Equilibrium: Historical Overview of an Analytical Problem Short Historical Overview of Tautomerization Dynamics Conclusions and Outlook ABSORPTION UV-vis SPECTROSCOPY AND CHEMOMETRICS: FROM QUALITATIVE CONCLUSIONS TO QUANTITATIVE ANALYSIS Introduction Quantitative Analysis of Tautomeric Equilibria Analysis of Real Tautomeric Systems Concluding Remarks STUDIES OF PHOTOINDUCED NH TAUTOMERISM BY STATIONARY AND TIME-RESOLVED FLUORESCENCE TECHNIQUES Introduction Photoinduced Proton/Hydrogen Atom Transfer Fluorescence Techniques for Studying Tautomerism Tautomerism in Bifunctional NH/N Azaaromatics Ab initio and DFT Computational Methods NH Tautomerism as a Tool in Biophysics Concluding Remarks FEMTOSECOND PUMP-PROBE SPECTROSCOPY OF PHOTOINDUCED TAUTOMERISM Introduction Ultrafast Pump-Probe Spectroscopy Dynamics from Pump-Probe Spectroscopy Reaction Mechanism Reaction-Path-Specific Wavepacket Dynamics in Double ESIPT Internal Conversion Summary and Conclusions NMR SPECTROSCOPY STUDY OF TAUTOMERISM IN SOLUTION AND IN THE SOLID STATE Introduction Methodologies of NMR Spectroscopy to Study Tautomerism Types of Tautomerism Studied by NMR Spectroscopy Conclusions and Outlook ISOTOPE EFFECTS ON CHEMICAL SHIFTS AS A TOOL IN THE STUDY OF TAUTOMERIC EQUILIBRIA Introduction Experimental Requirements Isotope Effects on Chemical Shifts Secondary Equilibrium Isotope Effects on CS Primary Isotope Effects Solid State Theoretical Calculations Examples Overview TAUTOMER-SELECTIVE SPECTROSCOPY OF NUCLEOBASES, ISOLATED IN THE GAS PHASE Introduction Techniques Guanine Adenine Cytosine Uracil and Thymine Base Pairs Outlook DIRECT EVIDENCE OF SOLID-STATE TAUTOMERISM BY DIFFRACTION METHODSD: ISOMERS, EQUILIBRIA, AND KINETICS Application of X-Ray Diffraction to Study Tautomerism Examples of X-Ray Diffraction Analysis of Proton Transfer Other Diffraction Methods Used to Study Proton Transfer Reactions DYNAMICS OF GROUND- AND EXCITED-STATE INTRAMOLECULAR PROTON TRANSFER REACTIONS Introduction Transition State Theory Two Examples of Tautomerization The Role of the Solvent Solvent Friction and Solvent Dynamics The Solvent Coordinate: Basics Polarization Fluctuations The Solvent Coordinate: An Application Electronic Rearrangement The Rug that Ties the (Classical) Room Together Quantum and Classical Quantum Decay Coupling Quantum and Classical Motion: A Simple Example Nonlinear Optics Femtochemistry Concluding Remarks FORCE FIELD TREATMENT OF PROTON AND HYDROGEN TRANSFER IN MOLECULAR SYSTEMS Introduction Computational Approaches to Proton Transfer Proton Transfer Reactions with MMPT Applications of MMPT Discussion and Outlook THE SCOPE AND LIMITATIONS OF LSER IN THE STUDY OF TAUTOMER RATIO Introduction The Taft-Kamlet LSER Methodology LSER Case Histories in the Field of Tautomerism Overview THE "BASICITY METHOD" FOR ESTIMATING TAUTOMER RATIO: A RADICAL RE-APPRAISAL Introduction Experimental Protocol The Derivation of Correction Factors Regularities Revealed by Correction Factors Complicating Factors in the Use of the "Basicity Method" Tautomeric Problems to Which the "Basicity Method" Is Inapplicable Overview QUANTUM CHEMICAL CALCULATION OF TAUTOMERIC EQUILIBRIA Introduction Computational Procedures Solvent Effects Applications of Quantum Chemical Methods to Tautomeric Equilibria Concluding Remarks Index