The inhibition of triphenylmethane primary dye fading in carbonless copying paper systems by singlet oxygen quenching bis(dithiocarbamato)nickel(II) complexes

摘要

Several of the dyes used in commerical carbonless copying systems act as singlet oxygen sensitisers, the production of which causes fading of the dyes [1]. A series of bis-(dithiocarbamato)nickel(II) complexes were synthesised and shown to be efficient singlet oxygen quenchers in solution in the presence of the acid activated clay. On the dry clay, however, only the hydroxyl-containing complexes were effective as they bound more efficiently to the clay. Fading was retarded more efficiently with fluoran TPM dyes, which produce more singlet oxygen, than phthalide TPM dyes. In some cases, the position and intensity of the #lambda#_max of the dyes was preserved efficiently.