Both phenomena of homochirality and sodium–potassium ion selectivity in cells have been regarded as important issues in the process of the origin of life. However, whether K+/Na+ selectivity was involved in homochirogenesis has never been considered. Herein, we report that a homochiral proline octamer shows high K+-selectivity. Coordination of K+ results in formation of a stable, noncovalent, D 4d -symmetric complex, as demonstrated by mass spectrometry, infrared photodissociation spectroscopy, and calculations. A cooperative relationship between an eight-coordinated metal cation and a homochirality-restricted topological hydrogen-bonded proline network is the key for the K+/Na+ selectivity. As the complex comprises merely the basic chiral amino acid, it provides a possible linkage between K+/Na+ selectivity and the origin of chirality on the prebiotic Earth.

Nowadays, it has been a focus to encapsulate a greater variety and amount of metal species into fullerene cages, due to their diverse structures and fascinating properties. Nevertheless, the encapsulation...

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The strong chiral preferences of some magic clusters of amino acids have attracted continually increasing interests due to their unique structures, properties and possible roles in homochirogenesis. However, how chirality can influence the generation and stability of cluster ions in a wild range of cluster sizes is still unknown for most amino acids. In this study, the preference for threonine clusters to form homochiral and heterochiral complex ions has been investigated by electrospray ionization (ESI) mass spectrometry. Abundant cluster [Thrn+mH]m+ ions (7 ≤ n ≤ 78, 1 ≤ m ≤ 5) have been observed for both samples of enantiopure (100% L) and racemic (50:50 L:D) threonine solutions. Further analyses of the spectra show that the [Thr14+2H]2+ ion is characterized by its most outstanding homochiral preference, and [Thr7+H]+ and [Thr8+H]+ ions also clearly exhibit their homochiral preferences. Although most of the triply charged clusters (20 ≤ n ≤ 36) are characterized by heterochiral preferences, the quadruply charged [Thrn+4H]4+ ions (40 ≤ n ≤ 59) have no obvious chiral preference in general. On the other hand, a weak homochiral preference exists for most of the quintuply charged ions observed in the experiment.

While numerous studies have focused on the impact of chirality on some magic amino acid clusters, this article investigates the effects of steric isomerization using 4-hydroxyproline octamers as a model...