Effects of Acceptor Structure on Charge-Transfer Complexation in Aqueous Polyelectrolyte Solution

Charge-transfer (CT) complexation between 1-pyrenesulfonate (PyS - ) (donor) and 9,10-anthraquinone-I sulfonate (I-AQS) (acceptor), and between PyS and 9,10-anthraquinone-2-sulfonate (2-AQS) (acceptor) in the solution of poly(l,l-dimethyl-3,5-dimethylenepiperidinium chloride) (PDDP + Cl - ) was investigated by absorption spectroscopy, viscosity and solubility measurements, and molecular orbital calculation. New broad UV bands corresponding to CT complexation between PyS and I- or 2-AQS - were observed only when the polycation was present in the system. A continuous variation method for both systems showed the stoichiometries of the CT complexes were both 1:1 in donor: acceptor composition. Reduced viscosity measurements showed to η sp /c. of PDDP + Cl - in Na + PyS/Na + 2-AQ - solutions decrease more rapidly than in Na + PyS - XNa + 1-AQS solutions as the salt concentration increase. Solubility measurements suggested that the polymer precipitated more easily in Na * PyS /Na + 2-AQS than in Na + PyS /Na + l-AQS solution. These results suggest that interactions between the polycation and the CT complex for Na + PyS - /Na + 2-AQS - are stronger than that for Na + PyS - Na + 1-AQS. Plausible structures of the Cl complexes are discussed on the basis of the HOMO and LL/MO energies and molecular orbital symmetry obtained by the MOPAC semi-empirical molecular orbital calculation program.