Coinage-metal pillarplexes hosts. Insights into host-guest interaction nature and luminescence quenching effects

Silver and Gold Pillarplex Pseudorotaxanes from α,ω-Dicarboxylic Acids

A series of pseudorotaxanes with supramolecular organometallic silver(I) and gold(I) pillarplexes acting as rings and different α,ω-dicarboxylic acids as axle components are reported. The successful formation of the host-guest complexes is shown by 1 H NMR spectroscopy and respective NMR titration. Additional evaluation with ITC titration experiments yielded dissociation constants (Kd ) ranging from 10-5 to 10-7  M. Single-crystal X-Ray diffraction analysis reveals a particularly exciting pore alignment of different examples in the solid state depending on the length of the guest. The work highlights, that dicarboxylic acids can penetrate the tight tubular pillarplex pore, paving the way to future mechanically interlocked molecules and materials.

Super-Excimer: Anomalous Bonding in a Metastable Excited-State Dimer of Superatomic Dimers

A new type of excimer formation was reported, which stems from an unexpected discovery of a short-lived excited-state dimer of superatomic dimers. In theoretical investigation of the dimer formation, it was found that the physical adsorption states maintain the closed-shell properties of the dimeric units via van der Waals interaction, while the chemical adsorption excited state is a broken-symmetry (BS) state, having a higher energy of about 0.5 eV. Potential energy surface calculations indicate that the short-lived metastable chemical bonding state can transform into energetically lower physical adsorption states by crossing a shallow energy barrier and eventually disintegrate into two ground-state dimers. Since the basic unit is a superatomic cluster, the chemical adsorption state discovered may be called "super-excimer", which opens up a new avenue for the discovery of tailorable excimer materials.

Crystal structure of a hexacationic Ag(I)-pillarplex-dodecyl-diammonium pseudo-rotaxane as terephthalate salt

A new pseudo-rotaxane, consisting of a tubular, organometallic Ag-pillarplex ring and dodecyldiammonium axle component, is introduced and investigated towards potential non-covalent interactions by Full Interaction Maps (FIMs). FIMs predict regions of probable supramolecular interactions solely at the organic ligands, namely the rim and the aromatic rings of the pillarplex. The results were compared to structural parameters experimentally obtained by single-crystal X-ray diffraction. The pseudo-rotaxane was crystallized as a hydrated terephthalate salt, and the molecular and the crystal structure are discussed. The experimentally observed interactions are quantified using Hirshfeld surface analysis. In contrast to the FIMs prediction, four different interaction modes can be experimentally observed in the solid-state: encapsulation of a guest molecule, hydrogen bonding, π- and metal interactions.

Why trans and not cis? – Molecular Dynamics and DFT study on selective separation of dihaloethene isomers using perethylated pillar[5]arene

The separation of mixtures of isomers is a daunting task. It is found that perethylated pillar[5]arene can separate trans-dichloroethene from its cis isomer. This work deals with the host-guest interactions...