Diastereoselective assembly of pentanuclear circular helicates

Abstract

Reaction of a ligand which contains two N-donor and O-donor tridentate domains separated by a 1,3-phenylene spacer unit with Zn(2+) ions results in a pentanuclear circular helicate [Zn(5)(L)(5)](10+) and this structure persists in both the solid and solution state. The formation of this high nuclearity species is governed by unfavourable steric interactions between the phenyl units which destabilize the simple linear helicate. Incorporation of enantiopure units within the ligand strand controls the diastereoselectivity with up to 80% d.e.

Inhibition of the photochromic behaviour of a 3,3-diphenyl-3H-pyrano[3,2-f]quinoline ligand by coordination to Ag(I) ions

“…The starting 3,3-diphenyl-3H-pyrano[3,2-f]quinoline was successfully synthesised using the method described by Guglielmetti et al [16], and subsequent transformation into ligand L 1 was accomplished in four efficient steps (Scheme 2 and ESI) in a similar fashion to other thiazole-containing ligands [17,18]. ).…”

Subcomponent Self‐Assembly of a Cyclic Tetranuclear FeII Helicate in a Highly Diastereoselective Self‐Sorting Manner

“…The most promising design strategies involve the use of anion template effects, control by metal‐ion radii or additional ligand–ligand interaction, or the implementation of steric strain that prevents the formation of linear helicates . In fact, there are only two studies up to now that involve enantiomerically pure bis(chelating) ligands that could be demonstrated to undergo diastereoselective self‐assembly to enantiomerically pure cyclic helicates . In both of these, the individual metal centres are bridged by single ligand strands, which have stereogenic elements in their outer periphery.…”