The packing and connectivity of tetrahedral units are
central themes
in the structural and electronic properties of a host of solids. Here,
we report one-dimensional (1D) chains of GeX2(X = S or
Se) with modification of the tetrahedral connectivity at the single-chain
limit. Precise tuning of the edge- and corner-sharing modes between
GeX2blocks is achieved by diameter-dependent 1D confinement
inside a carbon nanotube. Atomic-resolution scanning transmission
electron microscopy directly confirms the existence of two distinct
types of GeX2chains. Density functional theory calculations
corroborate the diameter-dependent stability of the system and reveal
an intriguing electronic structure that sensitively depends on tetrahedral
connectivity and composition. GeS2(1–x)Se2xcompound chains are also
realized, which demonstrate the tunability of the system’s
semiconducting properties through composition engineering.