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- Title
Factors Controlling Complex Morphologies of Isomorphous Metal‐Organic Frameworks.
- Authors
Singh, Vivek; Feldman, Yishay; Leitus, Gregory; Brumfeld, Vlad; Shimon, Linda J. W.; Lahav, Michal; van der Boom, Milko E.
- Abstract
We demonstrate here how nitrate salts of bivalent copper, nickel, cobalt, and manganese, along with an achiral organic ligand, assemble into various structures such as symmetrical double‐decker flowers, smooth elongated hexagonal bipyramids, and hexagonal prisms. Large morphological changes occur in these structures because of different metal cations, although they maintain isomorphous hexagonal crystallographic structures. Metal cations with stronger coordination to ligands (Cu and Ni) tend to form uniform crystals with unusual shapes, whereas weaker coordinating metal cations (Mn and Co) produce crystals with more regular hexagonal morphologies. The unusual flower‐like crystals formed with copper nitrate have two pairs of six symmetrical petals with hexagonal convex centers. The texture of the petals indicates dendritic growth. Two different types of morphologies were formed by using different copper nitrate‐to‐ligand ratios. An excess of the metal salt results in uniform and hexagonal crystals having a narrow size distribution, whereas the use of an excess of ligand results in double‐decker morphologies. Mechanistically, an intermediate structure was observed with slightly concave facets and a domed center. Such structures most likely play a key role in the formation of double‐decker crystals that can be formed by fusion processes. The coordination chemistry results in isostructural chiral frameworks consisting of two types of continuous helical channels. Four pyridine units from four separate ligands are coordinated to the metal center in a plane having a chiral (propeller‐type) arrangement. The individual double‐decker flower crystals are homochiral and a batch consists of crystals having both handedness.
- Subjects
METAL-organic frameworks; COPPER; COPPER crystals; COORDINATE covalent bond; NITRATES; MORPHOLOGY
- Publication
Chemistry - A European Journal, 2023, Vol 29, Issue 54, p1
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.202301825