Solvent-Directed Social Chiral Self-Sorting in PdL Coordination Cages.

A family of Pd cages prepared from ligands based on an axially chiral diamino-[1,1'-biazulene] motif (serving as a unique azulene-based surrogate of the ubiquitous BINOL moiety) is reported. We show that preparing a cage starting from the racemate of a shorter bis-monodentate ligand derivative, equipped with pyridine donor groups, leads to integrative ("social") chiral self-sorting, exclusively yielding the product, but only in a selection of solvents. This phenomenon is driven by individual solvent molecules acting as hydrogen bonding tethers between the amino groups of neighboring ligands, thereby locking the final coordination cage in a single isomeric form.

Modelling ligand exchange in metal complexes with machine learning potentials.

Metal ions are irreplaceable in many areas of chemistry, including (bio)catalysis, self-assembly and charge transfer processes. Yet, modelling their structural and dynamic properties in diverse chemical environments remains challenging for both force fields and methods. Here, we introduce a strategy to train machine learning potentials (MLPs) using MACE, an equivariant message-passing neural network, for metal-ligand complexes in explicit solvents.

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.

VCD spectroscopy reveals conformational changes of chiral crown ethers upon complexation of potassium and ammonium cations.

Two chiral derivatives of 18-crown-6, namely the host molecules 2,3-diphenyl- and 2-phenyl-18c6, serve as model systems to investigate whether VCD spectroscopy can be used to monitor conformational changes occurring upon complexation of guests. Host-guest complexes of both crown ethers were prepared by addition of KNO. The more bulky 2,3-diphenyl-18c6 is found to undergo major conformational changes upon encapsulation of K, which are revealed as characteristic changes of the VCD spectral signatures.