Chiral Induction and Amplification of Achiral Molecules Induced by Chiral Compounds in Solid Matrices

To demonstrate chiral induction and amplification in the solid state, we investigated co-crystals prepared from (S)- or (R)-1-phenylethylamine and achiral biphenyl-4-carboxylic acid by solvent-free crystallization. The chiroptical and optical properties of the co-crystals were characterized by circular dichroism spectroscopy, Fourier transform infrared spectroscopy, and time-dependent density functional theory calculations, revealing chiral induction, and amplification in the solid phase. The anisotropy factors-time plot showing the circular dichroism (CD) enhancement of the co-crystal prepared from chiral amine and achiral compounds by solvent-free crystallization in the KBr matrix. A correlation was shown between CD enhancement and the uptake of water on the KBr disk.