Weak H‐Bonds of Fluorophenyl Synthons Enabling Efficient and Entropically Stabilized Supramolecular Electro‐Optic Dendrimers

Weak hydrogen bonding interactions in singular fluorophenyl synthons enable efficient and entropically stabilized supramolecular electro-optic (EO) dendrimers. It demonstrates the highest effective EO activity reported to date for dendrimers measured by attenuated total reflection certification, low optical losses, and improved sub-T _g temporal stability against relaxation.

Herein, a series of supramolecular electro-optic (EO) dendrimers (EOD1-6) constructed using push–pull tetraene chromophores (PPT-phores) and Fréchet-type generation-1 benzyl ether dendrons with 2,3,5,6-tetrafluorophenyl or 2,4,6-trifluorophenyl groups at the periphery is presented. The fluorophenyl moieties possess enhanced CH acidity to form extended CH···F hydrogen bonds within complex functional dendrimers. Through comprehensive studies of optical absorption, electric field poling, EO activity, and thermal stability of EOD1-6/poly (methyl methacrylate) films, along with X-ray analyses of dendritic model compounds, it is elucidated that nonclassical hydrogen bonding of fluorophenyl synthons plays a pivotal role in modulating the strong dipole–dipole electrostatic interactions of PPT-phores. It facilitates the dipole orientation and enhances the stability of supramolecular EO dendrimers in poled films. Two of these dendrimers exhibit large r ₃₃ values of ≈170 pm V⁻¹ at 1306 nm and ≈120 pm V⁻¹ at 1541 nm, among the best EO activities to date for organic materials as certified by prism-coupled attenuated total reflection spectroscopy. Furthermore, examining subgap absorption for the films provides insights into the Urbach energy tail states. The notable properties and synthetic efficacy demonstrated by these dendrimers represent a transformative step in developing highly efficient, thermally stable, and low loss supramolecular organic EO materials for photonic applications.

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