Alkali Metal Organic–Inorganic Hybrid Compounds with Different Crystal Dimensions Show Phase-Transition, Dielectric, and SHG Properties Based on a Quasi-Spherical Amine (1S,4S)-2,5-Diazabicyclo[2.2.1]heptane

Abstract

Reactions of a chiral and quasi-spherical molecule [1S,4S-2,5−2.2.1-H 2 dabch]I 2 (1) with alkali metal halide MX (M = Na, K, Cs; X = Cl, Br) at room temperature produced a series of organic−inorganic hybrid (OIH) materials 4). The single-crystal X-ray diffraction analysis revealed that the organic−inorganic framework structures comprised of the templating ligand and alkali metal halides (NaBr, CsCl, KBr) displayed dimensions spanning from one-dimensional (1D) to three-dimensional (3D). Moreover, the results of both differential scanning calorimetry (DSC) and dielectric measurements demonstrated that compounds 1−4 displayed reversible, high-temperature phase transitions and noticeable dielectric anomalies. In addition, the temperature-dependent second harmonic generation (SHG) results revealed crystals 1 and 3 can switch from the SHG-ON to the SHG-OFF state, which was proved by the variable-temperature X-ray diffraction. This research aims to streamline the exploration of multifunctional second harmonic generation (SHG) and dielectric materials that have been synthesized using chiral ligands and alkali metals. This will provide researchers with enhanced opportunities to delve further into this specific research domain.

The Halogenation Effect Induces a Variety of Switchable Phase Transition and Second-Harmonic-Generation Materials

“…Organic–inorganic hybrid materials combine organic molecules with inorganic materials, integrating the flexibility of organic molecules with the stability and functionality of inorganic materials, providing a new avenue for optimizing the performance and multifunctional applications of phase-change materials. − Via the careful design of organic–inorganic hybrid structures, precise control of the physical properties of phase-change SHG materials can be achieved to meet the needs of different fields. − …”