The structure of azo dyes has attracted considerable attention in recent times , since they represent the largest class of dyes used in industry , and also has extensive applicability in analytical chemistry as acid - base , redox and metallochromic indictors 近年来,偶氮类染料的结构研究引起了人们的注意,因为它们是工业上所使用染料的最大类,并且作为酸碱指示剂、氧化还原指示剂、金属显色指示剂在分析化学中有着广泛的应用。