Synthesis and Characterization of Self‐Assembled Chiral FeII2L3 Cages. Issue 55 (6th September 2018)

• Record Type: Journal Article
• Authors: Sun, Bin; Nurttila, Sandra S.; Reek, Joost N. H.
• Is Part Of: Chemistry. Volume 24:Issue 55(2018)
• Page Start: 14693
• Page End: 14700
• Publication Date: 2018-09-06
• Subjects: cage compounds -- chirality -- coordination modes -- subcomponent assembly -- supramolecular chemistry; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201801077
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: We present here the synthesis of chiral BINOL‐derived (BINOL=1, 1′‐bi‐2‐naphthol) bisamine and bispyridine‐aldehyde building blocks that can be used for the self‐assembly of novel chiral Fe II 2 L3 cages when mixed with an iron(II) precursor. The properties of a series of chiral cages were studied by NMR and circular dichroism (CD) spectroscopy, cold‐spray ionization MS, and molecular modeling. Upon formation of the M2 L3 cages, the iron corners can adopt various isomeric forms: mer, fac ‐Δ, or fac ‐Λ. We found that the coordination geometry around the metal centers inR‐Cages 1 and2 were influenced by the chiral BINOL backbone only to a limited extent, as a mixture of cages was formed with fac and mer configurations at the iron corners. However, single cage species ( fac ‐RR‐Cage and fac ‐RS‐Cage ) that are enantiopure and highly symmetric were obtained by generating these chiral M2 L3 cages by using the bispyridine‐aldehyde building blocks in combination with chiral amine moieties to form pyridylimine ligands for coordination to iron. Next to consistent NMR spectra, the CD spectra confirm the configurations fac ‐(Λ, Λ) and fac ‐(Δ, Δ) corresponding toRR‐ andRS‐Cage, respectively. Abstract : Iron cage : The subcomponent assembly of chiral cages based on BINOL‐containing (BINOL=1, 1′‐bi‐2‐naphthol) scaffolds and chiral amines are reported. The M2 L3 cages can adopt various isomeric forms, but the BINOL building block does not steer the chirality at the metal corners during cage formation. Enantiopure cages are only obtained if this building block is used in combination with a chiral amine.