Lone-pair-induced formation of intrinsic one-dimensional SbSX (X = Cl, Br, I) helix chain materials.

Intrinsic one-dimensional (1D) helix chain materials are extremely rare in inorganic chemistry due to their novel structural features and complex syntheses. Herein, we report a class of inborn 1D helix chains, namely 1D SbSX (X = Cl, Br, I), that can exist stably. Through ab initio calculations, we demonstrate that the formation of this helical feature is facilitated by the lone pairs in antimony atoms. Owing to the different chemical bonds induced by the lone pairs, a phase transition between different helix chain phases can occur by applying extra elongation strain. More importantly, 1D SbSX helix chains possess superior flexibility. Under large elongation strains, the elastic energy is stored via bond angle redistributions, while the average bond lengths can remain invariant. Our work not only enriches the family of intrinsic 1D helical materials, but also provides a novel avenue for the diversification of low-dimensional phase change and flexible materials.