Chiroptical Recognition of Carboxylates with Charge-Neutral Double-Stranded Zinc(II) Helicates

Chirality analysis of small molecules for the determination of their enantiopurity is nowadays ruled by streamlined chromatographic methods which utilize chiral stationary phases. Chiroptical probes which rely on host-guest interactions are so far overshadowed by the latter but have the benefit of depending only on common spectroscopic techniques such as CD spectroscopy to distinguish enantiomers and to quantify their ratio. Interest into this receptor-based approach is constantly rising because non-invasive high-throughput screenings with a minimal waste production can be performed. In this study we investigate the possibility to utilize metal-based containers in form of charge-neutral helicates able to recognize anions for this purpose. Key building block of the helicates are triazole units which show rotational freedom and give rise to either a meso-structure or a racemic mixture of the right- and left-handed complex. A chiroptical response of the probe is observed upon recognition of chiral mono- or dicarboxylates and chirality analysis of tartrate is conducted by CD spectroscopy. Isomer truel - The guest calls out the winner. The dynamic interconversion of a neutral metal-based container-like helicate enables chiroptical recognition of chiral mono- and dicarboxylates by CD spectroscopy. Efficient guest recognition paired with an optimal chiral information transfer resulting from a coordinative binding mode allows the usage of the receptor for chirality analysis.image

Automated summary

Chirality analysis of small molecules can be efficiently performed through streamlined chromatographic methods or with the use of chiroptical probes relying on host-guest interactions. In this study, metal-based containers known as helicates are explored for their potential in recognizing anions and conducting chirality analysis. The helicates contain triazole units that exhibit rotational freedom and can form either a meso-structure or a racemic mixture, resulting in a chiroptical response upon recognition of chiral carboxylates. This receptor-based approach offers a non-invasive and waste-free solution for high-throughput screenings.