Direct Synthesis of Amorphous Metal–Organic Frameworks from Nanoclusters

The direct synthesis of amorphous metal-organic frameworks (aMOFs) is an appealing yet often avoided approach due to the perceived unpredictability of amorphous network formation. Here, we develop a strategy for aMOF synthesis using pre-formed nanoclusters and rigid organic linkers, providing enhanced control over disorder and defect chemistry while bypassing the traditional crystallise-amorphise approach. By systematically comparing this approach to other direct synthesis routes and using X-ray pair distribution function, thermogravimetric, and statistical analyses, we establish key design principles governing aMOF formation. We demonstrate that kinetic control-fast reactions under basic conditions at room temperature-suppresses crystallisation and drives amorphous network formation. The nanocluster approach consistently yields highly disordered frameworks with the shortest coherence lengths among direct synthesis methods. Additionally, we show that tuning metal composition through doping with kinetically inert cations restricts coordination reversibility, significantly increasing defect density and structural disorder. Structural analysis reveals that while aMOFs share motifs with crystalline polymorphs, they cannot be directly mapped onto known structures, highlighting the importance of more nuanced characterisation approaches. By developing a systematic approach to aMOF design, this work provides a foundation for tailoring structural disorder, expanding their potential for catalysis, adsorption, and transport applications.