Molecular engineering of bistetrafluoropyridine aryl ethers: a general platform for stable and programmable amorphous...

We report a highly efficient strategy for the synthesis of a novel class of amorphous, small-molecule organic glass formers (MOGs) derived from pentafluoropyridine (PFP). Utilizing a single-step, atom-economical, and highly scalable nucleophilic aromatic substitution S_NAr platform, a series of bistetrafluoropyridine aryl ethers (BTFPAEs) were prepared in excellent yields. This orthogonal approach leverages molecular asymmetry and rigid core architecture to effectively suppress crystallization, addressing a historical limitation of traditional MOGs. Thermal analysis revealed two discrete regimes of glassing behavior. Class I systems exhibit exceptional morphological stability, undergoing an irreversible transition to a robust, transparent amorphous glass upon initial melting with glass transition temperatures (T _g) precisely tunable between -15 °C and 53 °C. Exploiting this stability, we demonstrate the fabrication of homogeneous, melt-blended binary glasses with predictable, programmable T _g profiles that adhere strictly to the Fox equation. Class II systems yield highly versatile, metastable semi-amorphous matrices through controlled cooling dynamics. This work establishes a predictable structure-property relationship governing molecular symmetry, internal flexibility, and phase behavior, demonstrating that these resilient BTFPAE architectures hold significant promise as tailorable host matrices for a range of advanced material applications.