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Preferential Formation of Homochiral Helical Sandwich‐Shaped Architectures through the Metal‐Mediated Assembly of Tris(imidazoline) Ligands with a Set of d 3 –d 10 Transition‐Metal Ions
Author(s) -
Yan Liwei,
Wang Zhen,
Chen MingTsz,
Wu Ningjie,
Lan Jingbo,
Gao Xin,
You Jingsong,
Gau HanMou,
Chen ChiTien
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200801154
Subject(s) - isostructural , chemistry , crystallography , chirality (physics) , supramolecular chemistry , denticity , metal ions in aqueous solution , stereochemistry , stereocenter , metal , transition metal , steric effects , crystal structure , enantioselective synthesis , organic chemistry , chiral symmetry breaking , physics , quantum mechanics , nambu–jona lasinio model , quark , catalysis
Abstract A novel type of chiral tris‐monodentate imidazolinyl ligands (( S,S,S )‐ 4 and ( R,R,R )‐ 4 ) has been achieved in good yields. The ligands show a strong tendency to induce the generation of the discrete sandwich‐shaped M 3 L 2 architectures with programmed helicity through the edge‐directed complexation with a series of d 3 –d 10 transition‐metal ions, while taking advantage of the steric hindrance of the bulky substituents of the imidazoline rings to avoid the formation of extended metal–organic frameworks (MOFs). In spite of different coordination geometries, monovalent metal ions (e.g. Ag + ), divalent metal ions (e.g. Pd 2+ , Cu 2+ , Cd 2+ , Zn 2+ , Co 2+ , Mn 2+ , and Ni 2+ ), and even trivalent metal ions (e.g. Fe 3+ and Cr 3+ ) exhibit isostructural coordination. Installation of stereocenters fused onto the imidazoline rings results in favored handedness of the self‐assemblies through the expression of molecular chirality into supramolecular helicity. In the crystal structures of [M 3 {( S,S,S )‐ 4 } 2 ], the self‐assembly has to adopt the M form to relax the van der Waals repulsions of the phenyl and isopropyl groups. The replacement of ( S,S,S )‐ 4 with ( R,R,R )‐ 4 exclusively affords the opposite helicity ( P ). These results should provide important insights for the design of chiral helical capsule‐like assemblies.