Molybdenum Blue: A 200 Year Old Mystery Unveiled

“This is a substance or group of substances about which there has been much discussion” is a statement we read in an older standard textbook of inorganic chemistry with reference to a (usually) amorphous blue material that was first mentioned by C. W. Scheele in 1778 and discussed by J. J. Berzelius in 1826, and that today is known as “molybdenum blue”. Now based on the knowledge of compound 1 with an archetypal structure, the more than 200 year old mystery regarding the nature of this multifunctional material with its interesting properties has been partly unveiled.