engleski

From Concepts to Computations and Back : Design of Strong Organic Superacids and Superbases

A brief sketch of the life and work of Charles Coulson, one of the outstanding pioneers of quantum chemistry in the fifties and sixties of the last century, will be given. His requirement: "Give me insight, not numbers" was not only his individual hallmark, but also the main characteristic of the pre-computer era, when quantum chemistry was qualitative at its best. His departure from the scientific stage coincides with the rise of new emerging quantum chemistry, which has entered its third age. A messenger of the new times was paradigmatic methylene, which joined other milestone molecules like benzene, cyclopropane and hydrogen in the "Molecular Hall of Fame", with some later members like e.g. buckminsterfullerene. Methylene and its computed features represent a "phase transition" from qualitative to quantitative quantum chemistry. It is important to mention that computational (quantum) chemistry became a part of scientific revolution, called Computational Natural Science, which is firmly established by now as the third component of modern research alongside with experiment and theory providing strong ties between the two. As to chemistry, theory and computations became viable partners of the experimental research. However, in order to rationalize and understand myriad of numbers provided by experiments and computations, one needs sound physical models. Their role in science will be discussed in some detail. Adequate model and consequential concepts will be subsequently used in computational design of Broensted organic superacids and superbases, which has eventually led to a unified scale of all acids and bases. A dense ladder of predicted superbases and superacids should provide useful hints for their laboratory preparations. This would be very helpful in measuring their acid/base properties in the gas phase and their applications in various chemical reactions, not to mention catalytic processes. Indeed, computations already proved useful in directing synthesis of some "viable" superbases. Several examples of a successful collaboration with experimental chemists in obtaining new compounds of desired advantageous superbasic properties will be presented. Future prospects in acid-base chemistry will be discussed.

superacids; superbases

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