Polymerization and Electron Transfer Process, Studies on Substituted Ethylene

Abstract

It was the purpose of the present project to carry out some studies on Electron Transfer Process as pertinent to polymerization. Subjects for studies in the Electron Transfer Process are the electrochemical (redox) potentials, the solvation (free energies) of various species, the ion pair formation, the dis-proportional ation and dissociation equilibria, homogenous and hetrogenous electron transfer reaction rates. Since substituted ethylene, in general, and tetraphenylethylene in particular have been interlinked with polymer research , much of the present experimental work have been confined to tetraphenylethylene. The Lithium, Sodium, Potassium, Rubidium, and Tetra-butylammonium salts of tetraphenylethylene were prepared and their optical spectra recorded and computer resolved. The resolved spectra indicate three absorption bands helping in elucidating the structure of the salt. Attempt to make magnesium salt was partly successful, in the sense that, most probably, a monoanion radical is formed. Computer programs in BASIC language were developed for SCFMO calculations. Computer programs in BASIC were written and developed for Huckel, W-technique and perturbation methods. These methods were developed for the calculation of “inner” Oganization energy for hetrogenous electron transfer rate constant. The theoretical aspect of calculating the reversible (formal) electrode potential E° for irreversible (electron transfer) process through the calculation of the hetrogrenous rate constants was work out. Calculations were carried out on outer and inner reorganization energies, free energies of pf activation thus calculated were compared with the experimental values. Vltammetric studies were carried out on the tetraphenylethylene in DMF-Benzene mixture and HMPA. The hitherto unknown dis-proportionation constant (2T̼ ↔ T2-+ T) and the dissociation constants ( T2-, M+ ↔ T2- + M+) were calculated. As an attempt to fabricate an assembly for rotating disc electrode polarography, a manual palorograph was fabricated and tested. It was found to work satisfactory. The main features of this polarograph is that it is inexpensive (price approximately U.S.$100), portable and light (weight about 2 kg).