1,3-Diamino-2-hydroxypropane-N,N,N ',N '-tetraacetic acid stabilized amorphous calcium carbonate: nucleation, transformation and crystal growth

A low molecular weight organic molecule, 1,3-diamino-2-hydroxypropane-N,N,N',N'-tetraacetic acid, has been found that it could stabilize amorphous calcium carbonate (ACC) for at least three days in a gas diffusion reaction, also it could control the formation of hierarchical calcite crystals. The transformation process from ACC to calcite crystals has been systematically studied. Nucleation sites and intermediates were both captured by time-dependent experiments. It is found that ACC could form a close packed film on the substrate and part of the nucleation occurred on the film. After nucleation, another form of ACC conglomeration was found to be dissolved from inside. The intermediates on the substrate were found to be composed of fibres. A rod-dumbbell-sphere transformation phenomenon was observed. Selective adsorption and the mesocrystal transformation mechanism are assumed to play a key role in the formation of intermediates with different shapes and structures.