2-Iodo-3-meth­oxy-6-methyl­pyridine

The title compound, C7H8INO, which crystallizes with three independent mol­ecules in the asymmetric unit, was prepared by the reaction of 3-meth­oxy-6-methyl­pyridine with KI and I2 in tetra­hydro­furan solution. In the crystal structure, the three independent mol­ecules are arranged in a similar orientation with the three polar meth­oxy groups aligned on one side and the three non-polar methyl groups on the other side. The three mol­ecules, excluding methyl H atoms, are essentially planar, with r.m.s. deviations of 0.0141 (1), 0.0081 (1) and 0.0066 (2)Å. The three pyridine rings make dihedral angles of 58.09 (3) 66.64 (4) and 71.5 (3)°. The crystal structure features rather weak inter­molecular C—H⋯O hydrogen bonds, which link two mol­ecules into dimers, and short I⋯N contacts [4.046 (3) Å]

Spin-dependent localization of helical edge states in a non-Hermitian phononic crystal

As a distinctive feature unique to non-Hermitian systems, non-Hermitian skin effect displays fruitful exotic phenomena in one or higher dimensions, especially when conventional topological phases are involved. Among them, hybrid skin-topological effect is theoretically proposed recently, which exhibits anomalous localization of topological boundary states at lower-dimensional boundaries accompanied by extended bulk states. Here we experimentally realize the hybrid skin-topological effect in a non-Hermitian phononic crystal. The phononic crystal, before tuning to be non-Hermitian, is an ideal acoustic realization of the Kane-Mele model, which hosts gapless helical edge states at the boundaries. By introducing a staggered distribution of loss, the spin-dependent edge modes pile up to opposite corners, leading to a direct observation of the spin-dependent hybrid skin-topological effect. Our work highlights the interplay between topology and non-Hermiticity and opens new routes to non-Hermitian wave manipulations