Vaterite Polymorph Switching Controlled by Surface Charge Density of an Amphiphilic Dendron-calix[4]arene

The highly charged amphiphilic dendron-calixarene (1) forms stable monolayers at the air-water interface. Crystallization of CaCO 3 beneath monolayers of 1 selectively leads to growth of the metastable polymorph vaterite at low surface pressure, in distinct contrast to the growth characteristics of calcite or aragonite crystals under less highly charged calixarene monolayers, as we have reported previously. This result lends further support to our hypothesis that surface charge density is the dominant factor governing heterogeneous nucleation of CaCO 3 crystals at the monolayer/solution interface.