Selective Chiral Interactions between Hydrophilic/Hydrophobic Amino Acids and Growing Gypsum Crystals

In nature, selective interactions between chiral amino acids and crystals are important for the formation of chiral biominerals and provide insight into the mysterious origin of homochirality. Here, we show that chiral amino acids with different hydrophilicities/hydrophobicities exhibit different chiral selectivity preferences in the dynamically growing gypsum [001] steps. Hydrophilic amino acids show a chiral selectivity preference for their d-isomers, whereas hydrophobic amino acids prefer their l-isomers. These differences in chiral recognition can be attributed to the different stereochemical matching between the hydrophilic and hydrophobic amino acids on the [001] steps of growing gypsum. These different chiral selectivities resulting from the amino acid hydrophilicity/hydrophobicity are confirmed by the experimental crystallization investigations from nano regulation on dynamic steps, to microscopic modification of gypsum morphology, and to macroscopic precipitation. Furthermore, as the hydrophilicity of amino acids increases, the disparity in chiral selection rises; conversely, the increase in the hydrophobicity of amino acids results in a decline in chiral selection. These insights improve our understanding of the interaction mechanism between amino acids and crystals and provide insights into the formation process of chiral biominerals and the origin of homochirality in nature.

Selective Chiral Recognition between Amino Acids and Growing Gypsum Crystals

In nature, selective chiral interactions between biomolecules and minerals provide insight into the mysterious origin of homochirality. Here, we show growing gypsum crystals in a nonequilibrium state can recognize chiral enantiomers of amino acids. The chiral selection for amino acids with different functional groups by growing minerals are distinct. For 11 amino acids, the d-isomer slows dynamic gypsum growth more than the l-isomer, whereas for another 7 amino acids, the opposite was observed. These differences in chiral recognition are attributed to the different stereochemical matching between the chiral amino acids and the dynamic steps of growing gypsum. These stereoselective interactions between amino acid enantiomers and dynamic growing crystals can be applied toward the fabrication of gypsum cements to regulate their structure and mechanical properties. These findings provide insight into understanding the mechanism of the origin of homochirality in nature and suggest a pathway for constructing advanced functional materials.

Metal-Coordination-Induced Fusion Creates Hollow Crystalline Molecular Superstructures

In this work, we report the formation of superstructures assembled from organic tubular crystals mediated by metal-coordination chemistry. This template-free process involves the crystallization of molecules into crystals having a rectangular and uniform morphology, which then go on to fuse together into multibranched superstructures. The initially hollow and organic crystals are obtained under solvothermal conditions in the presence of a copper salt, whereas the superstructures are subsequently formed by aging the reaction mixture at room temperature. The mild thermodynamic conditions and the favorable kinetics of this unique self-assembly process allowed us to ex-situ monitor the superstructure formation by electron microscopy, highlighting a pivotal and unusual role for copper ions in their formation and stabilization.

21st century developments in the understanding and control of molecular solids

This highlight article surveys some of the key recent advances in crystallization techniques, polymorphism, co-crystals, amorphous materials and crystal engineering.

Chiral Imprinting in the Gas Phase

Undoing the twist: Recent successful attempts to change the relative populations of two otherwise identical enantiomers of a large gas-phase molecule using resonant microwave fields are highlighted. Specifically, the population of a specific enantiomer of a chiral terpene could be enhanced relative to the other enantiomer by the application of a sequence of microwave pulses in a phase- and polarization-controlled manner.