Chemists have synthesized a new blue pigment betanin, which is a part of beet juice. Unlike most other types of blue dyes, the new paint does not contain toxic ions of metals and is safe for living organisms. A study published in Science Advances.
One of the first reasons for people to engage in chemistry, became a necessity in the production of dyes. Improvement of natural and the creation of new artificial colors has led to the emergence of many chemical technologies. To find a stable and affordable natural dyes are very difficult, and particularly difficult this task in the case of blue color. Blue mineral pigments though are highly resistant, but often expensive and contain toxic metal cations, which limits their wide use. Many natural objects appear to be blue because of Rayleigh scattering — the scattering of light by objects whose size is smaller than its wavelength. For example, the wings of blue jays and butterflies morpho appear blue to the human eye because of its structure, but the substances of which they are composed, not blue.
Barbara Coelho de Freitas Doerr (Barbara Coelho de Freitas-Dörr) and her colleagues from the University of são Paulo, we synthesized a new blue dye, in which no metal ions. A new chromophore, the researchers called the “blue beet” (BeetBlue), because they received it from betanin, which is rich in beetroot juice. In an alkaline environment for half an hour at room temperature the molecules betanin has vtsepilas indole part, in place of which in the second stage of the synthesis, which also proceeded at room temperature, joined 2,4-dimethylphenol, forming a target molecule. The structure of the molecule, the researchers confirmed using NMR spectroscopy and mass spectrometry high resolution.