Understanding disorder and linker deficiency in porphyrinic zirconium-based metal-organic frameworks by resolving the Zr<sub>8</sub>O<sub>6</sub> cluster conundrum in PCN-221.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34035286.
- Also identified by DOI 10.1038/s41467-021-23348-w and PMC identifier 8149457.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Porphyrin-based metal-organic frameworks (MOFs), exemplified by MOF-525, PCN-221, and PCN-224, are promising systems for catalysis, optoelectronics, and solar energy conversion. However, subtle differences between synthetic protocols for these three MOFs give rise to vast discrepancies in purported product outcomes and description of framework topologies. Here, based on a comprehensive synthetic and structural analysis spanning local and long-range length scales, we show that PCN-221 consists of Zr<sub>6</sub>O<sub>4</sub>(OH)<sub>4</sub> clusters in four distinct orientations within the unit cell, rather than Zr<sub>8</sub>O<sub>6</sub> clusters as originally published, and linker vacancies at levels of around 50%, which may form in a locally correlated manner. We propose disordered PCN-224 (dPCN-224) as a unified model to understand PCN-221, MOF-525, and PCN-224 by varying the degree of orientational cluster disorder, linker conformation and vacancies, and cluster-linker binding. Our work thus introduces a new perspective on network topology and disorder in Zr-MOFs and pinpoints the structural variables that direct their functional properties.