Helical Superstructures of aC2-Symmetric Molecule Exhibiting Strong Second Harmonic Generation in the Solid-State

The crystallization solvent exerts a critical control of the nonlinear optical properties of helical superstructures in molecular crystals based on N,N'-bis(4-nitrophenyl)-(1R,2R)-diaminocyclohexane. While crystallization from ethyl acetate resulted in mutually orthogonal helices with different handedness, crystallization from ethyl acetate/hexane or acetyl acetone/hexane resulted in the formation of helical motifs of a single-handedness oriented in one direction. The latter showed a strong solid-state second harmonic generation capability.