LIQUID INTERFACES IN CHEMISTRY AND

BIOLOGY

Alexander G. Volkov David W. Deamer

Department of Chemistry and Biochemistry, University of California, Santa Cruz, California

Darreil L. Tanelian Vladislav S. Markin

Department of Anesthesiology and Pain Management, University of Texas, Southwestern Medical Center, Dallas, Texas

A Wiley-Interscience Publication

JOHN WILEY & SONS, INC.

New York • Chichester • Weinheim • Brisbane • Singapore • Toronto

CONTENTS

PREFACE

A. THERMODYNAMICS OF INTERFACES

1. Introduction to classical thermodynamics / 2

1.1. Basic concepts and definitions / 2 1.2. Thermodynamic potentials / 11 1.3. Generalization of thermodynamic potentials / 16 1.4. Chemical potential / 24 1.5. Multicomponent Systems / 32 1.6. External field / 43 1.7. Surfaces / 47 1.8. Irreversible processes / 63

2. Measurement of interfacial tension / 69

3. Adsorption at liquid Interfaces / 78

3.1. Gibbs method for planar interfaces / 78 3.2. Hansen's method / 87 3.3. Other definitions of surface excesses / 99 3.4. Volume and entropy of interface formation / 102 3.5. Curved interfaces / 111 3.6. Variables of the System / 120

B. ELECTRIFIED INTERFACES

4. Interfacial potentials / 130

4.1. Boundary potential difference / 130 4.2. Standard potentials and Standard Gibbs free energies / 132

v

VI CONTENTS

4.3. Distribution potentials / 136 4.4. Incomplete dissociation of the salt / 139 4.5. Complex formation in one of the phases / 140 4.6. The Donnan potential / 142 4.7. The Nernst potential / 144 4.8. The oxidation-reduction interfacial potential: Gibbs free energy of

electron and ion transport coupling / 144 4.9. The mixed potential / 146 4.10. The adsorption potential / 149 4.11. Verification of the thermodynamic theory of interfacial

potentials / 150 4.12. Measurement of interfacial potentials: the tetraphenylborate

hypothesis / 151 4.13. Methods for measuring the interfacial potential difference / 153 4.14. Hung's method of Galvani-potentials calculation: small Systems and

the effect of volumes / 160 4.15. Interfacial potential measurements as a tool for studying mechanisms

of enzymatic and catalytic reactions / 161

5. Electrocapillarity / 167

5.1. The electrocapillary equation / 167 5.2. Particular cases of the electrocapillary equation / 173 5.3. Thermodynamic charge at the interface / 176 5.4. Polarizable interface / 177 5.5. Non-polarizable interface / 183

6. Energetics of extraction / 192

6.1. Electrostatic contribution to the solvation energy / 195 6.2. The Born model / 198 6.3. Non-linear dielectric effects / 200 6.4. Other approaches to the Saturation problem / 204 6.5. The non-local electrostatic method / 208 6.6. Statistical solvent modeis / 210 6.7. Contribution of the solvophobic effect to the resolvation energy / 214 6.8. The total resolvation energy / 215 6.9. Dipole resolvation / 217

C. STRUCTURE OF INTERFACES

7. Interfacial structures and electrical double layers / 222

7.1. The modified Verwey-Niessen (MVN) model / 223

CONTENTS VII

7.2. Potentials of zero free charge and zero thermodynamic charge / 229 7.3. Measuring the capacitance of the electrical double layer / 239 7.4. Parsons-Zobel dependencies / 243 7.5. Potential discontinuities in the compact layer / 245 7.6. Specific adsorption: ionic association and ligand binding / 249 7.7. Adsorption isotherm and structure of the interface / 256 7.8. Roughness of the interface between two immiscible electrolyte

solutions / 266 7.9. Image forces / 270 7.10. Drawbacks and development of MVN and the Gouy-Chapman-Stern

theories / 278 7.11. Effects of variable dielectric permittivity / 282 7.12. Non-local electrostatics / 285 7.13. Electric double layer with hydration forces / 287 7.14. Modified Poisson-Boltzmann (MPB) model / 294 7.15. Ionic plasma in a continuous dielectric next to a charged

interface / 301 7.16. Ion-dipole plasma at a charged interface / 303 7.17. The Monte Carlo method and the double layer / 309 7.18. Computer simulations of ITIES / 313 7.19. Molecular dynamics and the structure of interfaces / 319

CHEMISTRY AT LIQUID INTERFACES

Interfacial catalysis / 324

8.1. Oil-water interface as a model of membranes / 324 8.2. Multielectron reactions at interfaces / 325 8.3. Solvent reorganization energy / 329 8.4. Selective catalytic properties of liquid interfaces / 331 8.5. Charge transfer reactions at oil-water interfaces / 333 8.6. Examples of chemical reactions at liquid interfaces / 334 8.7. Chlorophyll as a catalyst of electron transfer reactions in bilayers and

at the liquid hydrocarbon-water interface / 338 8.8. Porphyrins as interfacial catalysts / 342 8.9. Reduction of porphyrin at the octane-water interface controlled by

specific adsorption / 347 8.10. Coupling of two redox reactions at the octane-water interface / 351 8.11. Enzyme complexes of the mitochondrial respiratory chain / 355 8.12. ATPase / 359

VIII CONTENTS

Light energy conversion at liquid-liquid interfaces: artificial photosynthetic Systems / 361 9.1. Structure and composition of the oxygen-evolving complex in

vivo I 362 9.2. Thermodynamics of water oxidation / 362 9.3. Kinetic aspects of multielectron reactions / 365 9.4. Molecular mechanism of oxygen evolution in vivo I 368 9.5. Photoinduced charge transfer across an oil-water interface / 369 9.6. Artificial photosynthesis at the oil-water interface in the presence of

Chlorophyll / 370 9.7. Water photo-oxidation / 379

E. MEMBRANES

10. Membrane thermodynamics and electrostatics / 406

10.1. Structure and properties of biological membranes / 406 10.2. Membrane electrostatics / 410 10.3. Consecutive stages of membrane ion transport / 417 10.4. Mechanisms of passive permeation of ions and dipoles through

membranes / 422 10.5. Facilitated transport—mobile carriers and Channels / 433 10.6. Coupled transport and membrane equilibrium / 435

11. Mechanics of interfaces / 452

11.1. Definition of surface tension at a non-spherical interface / 452 11.2. Elastic properties of interfaces and the shape of vesicles / 464 11.3. Edge energy and pores in membranes / 475 11.4. Membrane fusion / 483

Bibliography / 492

APPENDIX / 544

INDEX / 547