The well-known dyes Congo Red and Bismarck Brown are azo compounds of complicated structure.
"The New Gresham Encyclopedia. Vol. 1 Part 3" by Various
There is a tune called "Congo Blues" by the innovative white xylophone/vibraphone artist Red Norvo, recorded by him with Bird and Diz in '45, and also featured on a radio broadcast of Diz with a Coltrane tenor solo in 1951.