Intraligand fluorescence of Zn(II) and Pt(II) complexes of pyridoxal thiosemicarbazone.

Pyridoxal (vitamin B 6 aldehyde) thiosemicarbazone (B 6 TSC) is deprotonated to its anion (B 6 TSC – H + ) in basic solution at pH = 9. It shows an intense green fluorescence with λ max = 500 nm and a quantum yield of unity. Zn(II)(B 6 TSC – H + )(acetate) displays an blue-green intraligand (B 6 TSC) fluorescence of moderate intensity. The complex cation [Pt(II)(B 6 TSC)Cl] + is isolated as tetraphenylborate. In basic solution (pH = 9) this cation is deprotonated to the neutral complex [Pt(II)(B 6 TSC – H + )Cl] which exhibits the same green intraligand fluorescence as the free anion (B 6 TSC – H + ) − . However, in the platinum complex this emission is much less intense. It is reduced to φ = 10 − 2 . [ABSTRACT FROM AUTHOR]