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 1 Demonstrates 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.



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Full Access

Keywords and Phrases

azines; crystal engineering; halogen bonding; nonlinear optical material; organic polar crystals

International Standard Serial Number (ISSN)

1521-3765; 0947-6539

Document Type

Article - Journal

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Publication Date

01 Jan 2024

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Chemistry Commons