Synergic role of pH and pigment's protonation state on the structure of amorphous calcium carbonate during its crystallization using pair di

Amorphous calcium carbonate (ACC) is an important metastable phase involved in the biomineralization processes used by organisms to form their skeletal parts. Although the pigmentation mechanisms are yet poorly known, color changes were observed from red, when the coloring polyhydroxylated naphthoquinone (PHNQ) molecules are synthesized in the cells to dark purple when they are occluded within the calcite phase. We propose that pH plays a crucial role in these color changes as the PHNQ’s protonation state leads to color from red to blue. Similarly, the analogue molecules (naphthazarin and juglone) we plan to use in this study, change color according to pH. Thus, we aim at measuring the local structural rearrangement occurring during the crystallization of ACCs synthesized at different pH (8-12.6) in the presence of the pigment molecules. This, will evidence the synergic role of pH and pigment’s ionic form on ACC stability and crystallization pathways.