Tunnelling in molecules : nuclear quantum effects from bio to physical chemistry Cover Preface Contents Chapter 1 Direct Observation of Tunnelling Reactions by Matrix Isolation Spectroscopy 1.1 Introduction 1.2 Description of Simple Mathematic Models for Tunnelling Computations 1.3 The Matrix Isolation Method: Creating the Conditions for Direct Observation of Tunnelling driven Chemistry 1.4 Interpretation of Kinetic Decays Observed in Cryogenic Matrices 1.5 NIR and IR induced Chemistry 1.6 Conformational Isomerizations by Tunnelling 1.7 Bond breaking Bond forming H atom Tunnelling (H shifts) 1.8 Heavy atom Tunnelling 3.3.1.1 Two dimensional Quantum Treatment of the D A and H D Coordinates 3.3.1.2 Classical Treatment of the D A Coordinate 3.3.2 KIE Analysis in the Classical Harmonic Limit 3.3.3 Effect of Anharmonic D A Interactions and Local Electric Fields 3.3.3.1 Background 3.3.3.2 A Simple Anharmonic Donor Acceptor Model 3.3.4 Application to Soybean Lipoxygenase 3.4 Electronically Adiabatic and Vibrationally Non adiabatic Proton Tunnelling in Biomolecules 3.4.1 Proton Tunnelling Rate Expression Using a Quantized D A Oscillator 2.4.1.1 Ozone 2.4.1.2 CMe5+ 2.4.1.3 Pericyclic Reactions 2.4.2 Some Unpublished Examples: Pericyclic Deazatation 2.5 Final Words Abbreviations References Chapter 3 Proton Tunnelling and Proton coupled Electron Transfer in Biological Systems: Theory and Experimental Analysis 3.1 Introduction 3.2 Basic Rate Expressions and Time Scale Separations 3.2.1 Time Scale Separations 3.2.2 Rate Expression for Electronically Adiabatic and Vibrationally Non adiabatic Proton Transfer with a Fixed Donor Acceptor Distance For the theoretical and experimental chemist this book provides a broad and conceptual perspective of the quantum tunnelling effect applied to the reactivity of molecules Author Contributions Acknowledgements References Chapter 2 Tunnelling Instability in Molecular Systems. An Exercise in Computational Chemistry Prediction Power 2.1 Introduction and Motivation 2.1.1 Stability in the Eye of the Beholder 2.2 A Primer: Computational Design of an Impossible Molecule 2.3 Theoretical and Computational Digression 2.3.1 Quantum Tunnelling: Theoretical and Practical Considerations 2.3.2 Electronic Structure Methods and Methodological Challenges 2.4 Quantum Tunnelling Instability: Past and Future 2.4.1 Some Published Examples 3.2.3 Rate Expression for Electronically Non adiabatic PCET with Fixed Donor Acceptor Distance 3.2.4 Basic Properties of the D A Sub system 3.2.4.1 Coordinate Space and Duschinsky Mixing 3.2.4.2 Einstein Approximation for the D A Mode Frequency 3.2.4.3 Linear Approximation for D A Coupling to the Tunnelling Rate 3.2.5 The Observed Rate and the Role of Protein Conformational Interconversions 3.3 Electronically Non adiabatic Proton coupled Electron Transfer in Biomolecules 3.3.1 Theoretical Treatment of D A Motion in the Quantum and Classical Limits