Chirality Change in Helical Crystals of Potassium Dichromate

抄録

Specific morphologies occasionally appear in the crystal growth in gels. Potassium dichromate (K₂Cr₂O₇) crystals grown in gelatin gel have been found to exhibit various morphologies by varying only initial concentrations of K₂Cr₂O₇ and gelatin in the medium. Particularly unique are huge helical crystals grown under the condition of high concentrations of both solute and gelatin, and right-handedness is overwhelmingly superior to left-handedness in helical chirality. We have found for the first time that huge left-handed helical crystals grow when adding acidic amino acids such as aspartic acid or glutamic acid, revealing the existence of an enantiomer of huge helical crystals of K₂Cr₂O₇. The present finding is expected to be relevant to biocrystallization such as the growth of seashells.