Lightest tetrahedral node: While silica-type tetrahedral frameworks can be readily emulated with divalent metal compounds (e.g., zinc imidazolate frameworks), it is more difficult with Li+. Here, a new series of Li-based zeolitic imidazolate frameworks (Li-ZIFS) has been synthesized by using a strategy based on charge-complementary ligands designed to prevent excessively negative charge surrounding Li sites. Among them, some exhibit a high CO2 adsorption capacity (e.g., 49 cm3 g−1 at 273 K and 1 atm).