Molecular π-Extension Strategy Enables All-in-One Polar Hybrid Glass-Ceramics Integrating Multidimensional Optical...

Mastering phase transitions of molecular materials is essential for regulating their optical functionalities, yet realizing glass materials that integrate multidimensional optical properties still poses a major challenge. Herein, we report a molecular π-extension strategy to modulate phase evolution for constructing all-in-one polar hybrid glass-ceramics featuring integrated multidimensional optical properties, as demonstrated by a pair of new hybrids, (benzyltriphenylphosphonium)[ReO₄] (1) and (1-naphthylmethyltriphenylphosphonium)[ReO₄] (2). Unlike the simple melting-crystallization cycle of 1, the π-expanded bulky naphthylmethyl moiety in 2 simultaneously strengthens steric hindrance and intermolecular interactions, elevating its melting point by 52 K relative to 1 and kinetically trapping the molten state. Accordingly, 2 undergoes reversible crystal-liquid-glass-crystal phase transitions. Thermal annealing transforms the highly transparent glass phase 2-G (transmittance = 97.82% over 400-800 nm) into polar hybrid glass-ceramic 2-GC with synergistic multidimensional optical performance. All phases exhibit distinctive multiband luminescence originating from combined concurrent Kasha emission, tunable anti-Kasha emission, and low-temperature phosphorescence. Remarkably, 2-GC achieves a 1.5-fold enhancement in second-harmonic generation compared with crystalline 2, and displays the first two-photon-excited upconversion fluorescence in hybrid glass-ceramic systems. This work verifies that molecular π-extension engineering offers a robust strategy for fabricating reconfigurable, all-in-one multifunctional photonic materials with integrated multidimensional optical properties.