Phenol-Driven Modulation Enables the Crystallization of Titanium Metal–Organic Frameworks

Titanium-based metal–organic frameworks (MOFs) remain among the most challenging frameworks to synthesize due to the high reactivity of Ti(IV) precursors, particularly when in combination with strongly coordinating phenolate ligands. Phenol is an untapped modulator for MOF synthesis that enabled the formation of a new crystalline Ti-MOF phase, otherwise unattainable through established modulators. We show how transient Ti-phenolate species formed in solution regulate titanium coordination equilibria and demonstrate the broader applicability of phenol modulation for several reported Ti-MOF systems. As a result of phenol modulation, we isolate a previously elusive crystalline titanium ellagate sustainable MOF, TUW-11, composed of monometallic Ti(IV) centers and plant-derived ellagic acid linkers. Three-dimensional electron diffraction, synchrotron X-ray techniques, and scanning transmission electron microscopy reveal a layered microporous framework with 1.1 nm channels. TUW-11 exhibits a narrow band gap, p-type semiconducting behavior, and ligand-centered visible-light photoresponse. These findings demonstrate phenol modulation as a powerful strategy for controlling titanium-phenolate framework formation and expand the synthetic toolbox available for Ti-MOF discovery.