Chemistry of 6-Monobrominated Indigo, MBI

Hiroko Ajiki


6-monobrominated indigo, MBI, is a component of a historically important and the most expensive colorant, Tyrian Purple.

The colorant is remarkably stable under the sun, in the air and after extensive washing with water. The color is still vivid after thousands of years. Even though it has such a high stability, MBI and Tyrian Purple have color changes from purple to blue upon temperature changes. This color change has been known for long to certain people, but the mechanism of the color change was unknown.

Tyrian Purple also has recently attracted interests for applications towards semiconducting material due to its ambipolar property and high stacking structure and towards its biomedical applications.

Though other chemicals in the colorant have been studied and analyzed well, MBI is the least studied and understood chemical.

The full investigation of the chemistry of MBI has been conducted and reported in this study.