Formation of Metallo-Polymers and -Macrocycles by Complexation of Alkyl- Linked Di-Terpyridines with Iron(II) Ions
-
Andres, Philip R.; Schubert, Ulrich S.
- Abstract:
- The complexation of bridged di-terpyridine ligands with
iron(II) leads to new metallo-supramolecular assemblies. Di-terpyridine
ligands were synthesized using nucleophilic substitution of
4¢-chloro-2,2¢:6¢,2¢¢-terpyridine with different dialcoholate alkyl
and dithiolate alkyl nucleophiles. Upon addition of iron(II) chloride
the formation of metallo-polymeric structures via metal-to-ligand
complexation is observed. The metallo-polymeric assemblies presented
here contain low molar mass (cyclo)-alkyl bridged di-terpyridine
ligands of which one is achiral and two others are
enantiomers. For both cases, characterization using NMR and UV/
Vis spectroscopy shows complex formation and indicates the formation
of metallo-supramolecular polymers. For the non-polymeric
system, formed at room temperature, it could be shown that upon
heating exchange takes place and that the thermodynamically favored
product is formed. Using column chromatography, the first
two major fractions of the mixture could be separated and analyzed.
MALDI-TOF mass spectrometry and 1H NMR spectroscopy confirmed
the formation of metallo-macrocyclic assemblies. For the
chiral system, circular dichroism (CD) experiments showed the formation
of an optically active material, with the spectra of the enantiomeric
assemblies being mirror-symmetric.
- Year:
- 2004
- Type of Publication:
- Article
- Keywords:
- terpyridines; polymers; iron; macrocycles; supramolecular chemistry
- Journal:
- Synthesis
- Number:
- 8
- Pages:
- 1229 - 1238