When a racemic mixture of chiral building blocks self‐assembles to form discrete molecular or supramolecular cages, the system can adopt either social or narcissistic chiral self‐sorting. However, control over such chiral self‐sorting is hard to achieve with a desired choice of outcome. Herein, we report anion templated high‐fidelity chiral self‐sorting during the coordination‐driven self‐assembly of [Pd2L4] metal‐organic cages, with a racemic mixture of an axially chiral ligand. Upon varying the counter‐anions, the outcome of the choice of chiral self‐sorting, whether social or narcissistic, leading to kinetically favored heterochiral or thermodynamically favored homochiral cages, can be controlled through specific anion encapsulation. Non‐encapsulating anion afforded a mixture of all possible diastereomers. Anion exchange enabled structural transformations between the diastereomers and the conversion of the mixture of diastereomers into homochiral diastereomers.
Chiral self‐sorting during the formation of cage‐like molecules continues to fascinate and advance our understanding of the phenomenon in general. Herein, we report the chiral self‐sorting in the Pd6L12‐type metal‐organic cages. When a racemic mixture of axially chiral bis‐pyridyl ligands undergo coordination‐driven self‐assembly with Pd(II) ions to form Pd6L12‐type cages, the system has the option of chiral self‐sorting to afford any of at least 70 pairs of (one homochiral and 69 heterochiral) enantiomers and 5 meso isomers or a statistical mixture of everything. However, the system resulted in diastereoselective self‐assembly through a high‐fidelity chiral social self‐sorting to form a racemic mixture of D3 symmetric heterochiral [Pd6(L6R/6S)12]12+/[Pd6(L6S/6R)12]12+ cages.
The design and synthesis
of a cleft-shaped bis-diarylurea receptor
for chloride anion transport is reported in this work. The receptor
is based on the foldameric nature of N,N′-diphenylurea upon its dimethylation. The bis-diarylurea receptor
exhibits a strong and selective affinity for chloride over bromide
and iodide anions. A nanomolar quantity of the receptor efficiently
transports the chloride across a lipid bilayer membrane as a 1:1 complex
(EC50 = 5.23 nm). The work demonstrates the utility of
the N,N′-dimethyl-N,N′-diphenylurea scaffold in anion
recognition and transport.
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