The spectroscopic, photochemical and photopolymerization properties of four novel 1-substituted water soluble 2-hydroxy-3-(9-oxo-9H-thioxanthene-4-yloxy)-N,N,N-trimethyl-l-propanaminium chloride salts are examined. From absorption and fluorescence and phosphorescence analysis substitution in the 1-position by halogen groups induces more charge-transfer character than aliphatic alkyl groups. The photoreduction quantum yields of all the 1-substituted derivatives in the presence of a tertiary amine are lower than that for the unsubstituted derivative which is again indicative of the higher degree of charge-transfer content of the lowest excited states. The reduced activity of the 1-substituted derivatives is also reflected in the microsecond flash photolysis data on radical and radical anion formation. The addition of a tertiary amine, however, enhances the formation of both species probably due to triplet exciplex formation. Photopolymerization and photoinitiation rates for acrylamide are also reduced by 1-substitution. The data are discussed in terms of the nature of 1-substitution increasing the degree of charge-transfer character of the lowest excited singlet and triplet states.
Посилання на статтю:
Spectroscopic properties and photopolymerization activities of water soluble 1-substituted derivatives of 2-hydroxy-3-(9-oxo-9H-thioxanthene-4- yloxy) -N,N,N-trimethy1-1 - propa nami n i u m chloride salt / N. S. Allen*, M. Edge and I. Sideridout // Polymer. – 1993. – Vol 34. – P. 21-24.
