The main objective of the research to be carried out within this project, is to provide basic information about intrinsic molecular properties and reactivity of carefully selected families of organic compounds and model systems which mimick large biologically active molecules both in the ground and electronically excited states. Investigations will encompass two mutually independent lines of research: (a) protonation and deprotonation reactions with an emphasis on synthetically and biologically important transformations and (b) reactivity of strained cyclic molecules under standard and extreme (high pressure and microwave irradiation) reaction conditions. The first line of research includes synthesis of a new type of guanidine bases and superbases characterized by a presence of strong intramolecular hydrogen bonds in their conjugate acids. Their structural properties and basicity will be meticulously examined. Considerable attention will be also payed to determining their catalytic activity in a number of synthetically important reactions, the most important being transesterification, which is used in production of commercially important biodiesel. Studies of the electronically excited states will be confined to interactions of the peptide bond (modelled by formamide) with proton and metal ions and to investigation of the intermolecular hydrogen transfer within life molecules (modelled by pyrolle/NH3 complex). The work within the second line of research will be focused on preparation and basicity studies of synthetically important enolate anions embeded into small rings and to the hithertho poorly studied bond strech isomerism reactions of some carefully selected organic molecules. The methods employed will comprise a balanced use of experimental (synthetic and spectroscopic) techniques and high level quantum-chemical calculations. Computational methods will be used in selection of appropriate molecular model systems, disclosure of their electronic features and as a guidance in chemical syntheses. The results are expected to provide significant new information on the studied topics and to contribute to a deeper understanding of organic reactivity in general. This will ultimately lead to preparation of new compounds with targeted properties and their application in chemical industry. It is anticipated that they will also aid in developing new and ecologically acceptable procedures useful in exploiting renewable energy sources.