Thermochemical aspects of proton transfer in the gas phase

The beginning of the twentieth century saw the development of new theories of acidity and basicity, which are currently well accepted. The thermochemi stry of proton transfer in the absence of solvent attracted much interest d uring this period, because of the fundamental importance of the process. Ne vertheless, before the 1950s, few data were available, either from lattice energy evaluations or from calculations using the emerging molecular orbita l theory. Advances in mass spectrometry during the last 40 years allowed st udies of numerous systems with better accuracy. Thousands of accurate gas-p hase acidities or basicities are now available, for simple atomic and molec ular systems and for large biomolecules. The intrinsic effect of structure on the Bronsted basic or acidic properties of molecules and the influence o f solvents have been unravelled. In this tutorial, the basics of the thermo dynamic principles involved are given, and the mass spectrometric technique s are briefly reviewed. Advances in the design and measurements of gas-phas e superacids and superbases are described. Recent studies concerning biomol ecules are also evoked. Copyright (C) 2001 John Wiley & Sons, Ltd.