Antithermal Quenching and Nonlinear Optical Response in Chiral Cation-Coordinated Hybrid Manganese Chlorides

Chiral organic-inorganic hybrid metal halides (OIHMHs) represent an emerging class of chiroptical materials with promising applications in chiral optoelectronic and spintronic devices. However, the thermal quenching (TQ) effect of chiral OIHMHs severely restricts their practical deployment under high-temperature conditions. Herein, we synthesized a pair of chiral hybrid manganese chlorides, R/S-DACAMnCl₃, featuring coordinated chiral cations. The enantiomers crystallized in the noncentrosymmetric space group P2₁2₁2₁, consisting of infinite chains of edge-sharing MnOCl₅ octahedra. Benefiting from robust coordination and hydrogen-bonding interactions, R/S-DACAMnCl₃ single crystals (SCs) exhibited intense circularly polarized luminescence at 628 nm, with luminescence dissymmetry factors of 7 × 10⁻³ and -6 × 10⁻³, respectively. Specifically, R-DACAMnCl₃ SCs displayed a striking anomalous antithermal quenching (ATQ) effect, in which the emission intensity was increased by 78% as the temperature was elevated from 100 to 380 K. We demonstrated that the ATQ effect in R-DACAMnCl₃ SCs was mainly driven by phonon-assisted anti-Stokes vibronic coupling, with thermally induced lattice expansion playing a secondary role. Furthermore, R/S-DACAMnCl₃ SCs exhibited strong second harmonic generation signals at 460 and 470 nm upon excitation with 920 and 940 nm laser light, respectively. These findings provide valuable insights into the design of high-performance chiral OIHMHs, advancing their practical applications in chiral optoelectronic devices.