In the late 70-ies of the XXth century the research team from Moldova headed by Acad. Gheorghe Duca, in collaboration with the colleagues from Moscow, Institute of Chemical Physics of Russian Academy of Sciences, revealed in detail the role of the transition metal (Mn, Fe, Cu) complex compounds  in oxygen and hydrogen peroxide molecules activation, followed by the development of oxidation-reduction processes in technological and environmental matters. The theory of the redox-processes with the involvement of partial charge transfer complexes (PCTC) has been developed, in accordance to which the thermodynamic equilibrium between the main and electron-excited state of a complex is established as a result of a partial transfer of one or two (pair) electrons from donor towards the acceptor under the room temperature. Due to this phenomenon, PCTC, entering a chemical reaction, can exhibit both the properties of initial reagents and products of the complete one- or two-electron transfer, showing the specific reactivity.

 

It was shown that during the partial charge transfer, the molecular mechanisms of oxidation-reduction reactions are possible, being realized without the exit of active intermediate particles from the metal coordination sphere.  The side processes of radicals interaction with substrate particles are thus non-realized, and the process selectivity is rising, which is important for the targeted technological processes. 

 

At the same time, it was shown that in many systems, such as wine, juices, natural water bodies, PCTC can initiate the radical processes, which can affect the products quality or ensure chemical auto-purification of natural water environment. The charge distribution changes within the PCTC and accompanying modifications in the interacting molecules electron structure are causing the essential changes in the electric field gradient on each atom of the complex.

 

The detailed study of the behavior and properties  of a series of PCTC made it possible to estimate and prove the vitality of the proposed theory, with regard to the homogeneous catalysis processes, waste water treatment, juice and wine production, development of chemical-biological processes within the human organism, etc.

 

The elaborated theory has become an important chain in the development of both fundamental science and elaboration of technologic processes and methods.

 

The results of numerous original research conducted on the base of PCTC theory, have been included in the textbooks for the university students, as well as the monographs published in Moldova, Romania, Russia, Germany, in the prestigious research journals and international conferences proceedings.