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Abstract An improved design is described for ferroelectric crystals and implemented with the “methoxyphenyl series” of acetophenone azines, (MeO−Ph, Y)‐azines with Y = F (1), Cl (2), Br (3), or I (4). The crystal structures of these azines exhibit polar stacking of parallel beloamphiphile monolayers (PBAMs). Azines 1, 3, and 4 form true racemates whereas chloroazine 2 crystallizes as a kryptoracemate. Azines 1–4 are helical because of the N−N bond conformation. In true racemates the molecules of opposite helicity (M and P) are enantiomers A(M) and A*(P) while in kryptoracemates they are diastereomers A(M) and B*(P). The stacking mode of PBAMs is influenced by halogen bonding, with 2–4 showcasing a kink due to directional interlayer halogen bonding, whereas fluoroazine 1demonstrates ideal polar stacking by avoiding it. Notably, (MeO−Ph, Y)‐azines display a stronger bias for dipole parallel alignment, attributed to the linearity of the biphenyl moiety as compared to the phenoxy series of (PhO, Y)‐azines with their non‐linear Ph−O−Ph moiety. The crystals of 1–4 all feature planar biphenyls and this synthon facilitates their crystallization through potent triple T‐contacts and enhances their nonlinear optical (NLO) performance by increasing conjugation length and affecting favorable chromophore conformations in the solids. 

Abstract Invited for the cover of this issue are Harmeet Bhoday, Nathan Knotts, and Rainer Glaser at the Missouri University of Science and Technology. Joe Miner, the university mascot, is a silent and honorary co‐author and personifies the spirit of the old west and the determination to succeed (our emphasis). The image depicts one (MeO‐Ph, Y)‐azine molecule and a model of a perfectly polar stacked bilayer. The floodlight illumination presents a graphic metaphor of second‐harmonic generation (frequency doubling) by the crystalline ferroelectric materials. Read the full text of the article at 10.1002/chem.202400182.