Tectonic arrangement of BaCO3 nanocrystals into helices induced by a racemic block copolymer.

Morphosynthesis strategies inspired by biomineralization processes gives access to a wide range of fascinating and useful crystalline mesostructures. Biomimetic synthesis of inorganic materials with complex shapes can now be used to control the nucleation, tensorial growth, and alignment of inorganic crystals in a way previously not practicable. Double hydrophilic block copolymers (DHBCs) consisting of a hydrophilic block strongly interacting with inorganic minerals, and a non-interacting hydrophilic block, were recently introduced for the control of mineralization reactions. DHBCs are 'improved versions' of the previously used polyelectrolytes or amphiphiles and are extraordinarily effective in crystallization control. Here, we report on the formation of helices of achiral BaCO(3) nanocrystals in the presence of a racemic DHBC suggesting that a helical alignment can be induced by racemic polymers through selective adsorption on the (110) face of nanocrystals. This mechanism is the key for a better understanding of the self-assembly of chiral organic-inorganic superstructures that don't follow a direct template route.