Abstract
Novel pyridylformazane derivatives have been synthesized by introducing various substituents into a benzene ring. Their characteristics as analytical reagents, such as acid dissociation constants and color reactions with various transition metal ions, have been investigated. A linear relationship has been established between Hammett′s substituent constants (σ) and acid dissociation constants (pka1, and pka2), and between (σ) and stability constants of metal complexes. Introduction of a nitro group into mesa- or para-position of the benzene ring has increased the sensitivity to a great extent; the molar absorption coefficient (logε) of the zinc complex was 4.91 and the stability constant (log KZnA2) was 18.97±0.05.
