Dynamic-to-static switch of hydrogen bonds induces a metal–insulator transition in an organic–inorganic superlattice

Hydrogen bonds profoundly influence the fundamental chemical, physical and biological properties of molecules and materials. Owing to their relatively weaker interactions compared to other chemical bonds, hydrogen bonds alone are generally insufficient to induce substantial changes in electrical properties, thus imposing severe constraints on their applications in related devices. Here we report a metal–insulator transition controlled by hydrogen bonds for an organic–inorganic (1,3-diaminopropane)0.5SnSe2 superlattice that exhibits a colossal on–off ratio of 107 in electrical resistivity. The key to inducing the transition is a change in the amino group’s hydrogen-bonding structure from dynamic to static. In the dynamic state, thermally activated free rotation continuously breaks and forms transient hydrogen bonds with adjacent Se anions. In the static state, the amino group forms three fixed-angle positions, each separated by 120°. Our findings contribute to the understanding of electrical phenomena in organic–inorganic hybrid materials and may be used for the design of future molecule-based electronic materials. Hydrogen bonds impact the chemical, physical and biological properties of molecular materials, but are rarely able to induce significant changes in electrical properties. Now a dynamic-to-static transition of hydrogen bonds in an organic–inorganic superlattice has been shown to yield a metal–insulator transition with an on–off ratio of 107 in electrical resistivity.