Direct Observation of Li⁺ Ions Trapped in a Mg²⁺-Templated Metal–Organic Framework

Herein we report the first example of a metal–organic framework (MOF) in which the location of Li⁺ ions trapped in the porous confinement can be unambiguously defined by single-crystal X-ray diffraction. Furthermore, the Li⁺-doped MOF shows significant enhancement in gas uptake as well as selective adsorption of CO₂ over CH₄.