Indoloquinoxaline誘導体の金属錯体に関する研究(第2報 ) : Hydroxyindoloquinoxaline金属錯体の分光光度法による安定度定数の測定

抄録

The ionization constants (pK_a) of 1-hydroxy-, 4-hydroxy-, 7-hydroxy-10-chloro- and 7-chloro-10-hydroxy-indo1o[2, 3-b]quinoxaline (I, II, III and IV), and the stability constants of some of the transition metal complexes were determined spectrophotometrically. The difference of pK_a the UV spectrum between I and II were found to be very slight and we did not observe any significant differences of the stability constants. The prepared complexes were much different from that of oxine in solubilities, stabilities and shifts of absorption maximum in the complex formation and they were found to be less stable in aqueous solution. Because of the poor solubility of III and IV in 50% dioxane, the stability constants of their metal complexes could not be determined under the same conditions as I and II, and they have been measured in alcohol for III and in 50% alcohol for IV : they are less stable than those of I and II.