Metal–organic frameworks (MOFs) are a revolutionary new class of crystalline solids that can be designed to trap myriad kinds of matter, including greenhouse gases, or to be used as nanosized drug carriers. They can also pull water from desert air. A chief characteristic of MOFs, which some have been called “miracle materials,” is how much empty space they comprise. Often described in the scientific literature as “ultra highly porous,” the sponge-like nano-structures have the greatest internal s...