Fig. 4: Chirality of ClickZip chelates.
From: Ultra-inert lanthanide chelates as mass tags for multiplexed bioanalysis
Inherent chirality of the molecules is given by rotation of the pendant arms (Λ or Δ) and of the four ethylene units in the cyclen ring (λλλλ or δδδδ). In theory, four isomers are possible: two twisted square antiprismatic (TSA) enantiomers (Λλλλλ and Δδδδδ), and two square antiprismatic (SA) enantiomers (Δλλλλ and Λδδδδ). The ClickZip chelates exclusively adopt the TSA arrangements Λλλλλ and Δδδδδ, which were observed together in all solid-state structures as well as in solution. These two forms interconvert on the time scale of hours at 37 °C (Supplementary Fig. 22). Both enantiomers shown here were found in the crystal structure of [{Lu}]+[ClO4]−·5H2O. Thermal ellipsoids were set at 50% probability.
