Synthesis and characterization of new-type charge-transfer salts based on basic dye and tungstophosphoric acid

Three new-type charge-transfer salts were synthesized based on the reaction of three kinds of basic dye (crystal violet, safranine T, methylene blue BB, respectively) and tungstophosphoric acid of Keggin structure. The composition, thermal stability and optical property of the new compounds were characterized by element analysis, TG-DTA, IR and UV-vis. The results indicate that the Keggin structure of tungstophosphoric anion was not destroyed on the conditions of synthetic reaction; the successful synthesis of the charge-transfer salts was due to the combination of the lone-pair electrons in the basic dye and the proton H⁺ in the tungstophosphoric acid. The charge-transfer phenomenon from the organic cation to the tungstophosphoric anion under the condition of being excited by the light was observed.