Regulation of metal valence states for enhancing second harmonic generation performance of chiral tin halides

(R-/S-4Sn) crystals. This transformation significantly enhances the second harmonic generation (SHG) response owing to the reduction in crystal spatial symmetry following the change in the valence states of tin. This work highlighted the potential of low-dimensional chiral tin-based MHPs in high-performance NLO applications, offering a foundation for future exploration in this field.