Controlling the Polymorphism and Topology Transformation in Porphyrinic Zirconium Metal-Organic Frameworks via Mechanochemistry

The mechanochemical approach has been used here for preparation and polymorph resolution in porphyrinic MOF-525/PCN-223 zirconium metal-organic frameworks system, achieving pure target MOF phases in 30-60 minutes milling. In specific reaction condition, MOF-525 forms rapidly by milling but transforms into PCN-223, confirming it to be the kinetic phase in this polymorphic system. ESR measurements showed a strong effect of internal MOF structure on the spin structure of paramagnetic cations coordinated into porphyrin linkers, which show potential for these polymorphic MOFs in spintronics application.