Crystallography worships order, and MOF chemistry inherited the faith: one linker, one node, one perfect repeat. Deng and colleagues committed productive heresy by cooking up to eight differently functionalized terephthalates into single MOF-5-type crystals, producing frameworks whose backbone is periodic but whose chemical decoration is deliberately scrambled. They called them multivariate, MTV, MOFs.
Two results carry the paper. First, the functional groups genuinely coexist within one phase rather than segregating into separate crystals, though the precise spatial arrangement, random, clustered or gradient, remained beyond 2010 characterization, an admitted blind spot the group spent the next decade illuminating. Second, and more provocative, the whole beats the parts: one ternary combination showed 400 percent better selectivity for CO2 over CO than its best single-linker parent, evidence of synergy no pure framework could replicate.
The critical reading: with combinatorial mixtures comes combinatorial characterization debt. Batch reproducibility of linker ratios, whether gains come from designed synergy or accidental defect chemistry, and the difficulty of assigning mechanism when the active site is a statistical ensemble all complicate the MTV program, and the field is still building the tools this vision requires.
Its influence is hard to overstate. MTV logic, treating composition as a continuous, mixable variable rather than a discrete choice, now underpins mixed-metal catalysts, gradient sorbents and the entire MOF-alloying literature. This is the paper that taught a crystal-obsessed field to love controlled disorder.