We have observed the mixed-valence and radical cation dimer states of a glycoluril-based molecular clip with tetrathiafulvalene (TTF) sidewalls at low concentration (1 mM) at room temperature. This molecular clip has four consecutive anodic steps in its cyclic voltammogram, which suggests a sequential oxidation of these TTF sidewalls to generate species existing in several distinct charge states: neutral monomers, mixed-valence dimers, radical cation dimers, and fully oxidized tetracationic monomers. The observation of characteristic NIR spectroscopic absorption bands at approximately 1650 and 830 nm in spectroelectrochemistry experiments supports the presence of intermediary mixed-valence and radical cation dimers, respectively, during the oxidation process. The stacking of four TTF radical cations in the dimer led to the appearance of a charge-transfer band at approximately 946 nm. Nanoelectrospray ionization mass spectrometry was used to verify the tricationic state and confirm the existence of other different charged dimers during the oxidation of the molecular clip.

A brake orbit is an orbit that starts with zero initial velocity. The purpose of this paper is to find periodic brake orbits in the isosceles three-body problem. We use various shooting arguments; we follow a curve of brake initial conditions under the flow until it reaches a suitable surface, and show that the image curve includes a point that corresponds to a periodic orbit. As a result, we prove the existence of six types of periodic brake orbits.

Small is beautiful: The [2]pseudorotaxane formed from dipropargylammonium tetrafluoroborate and the crown ether [21]crown‐7 on SiO2 was stoppered with 1,2,4,5‐tetrazine in a ball‐milling process (see X‐ray structure). This new and efficient solvent‐free reaction led to the isolation in high yield (81 %) of the smallest [2]rotaxane reported to date.

Making the right choice: Tetrakis(3,5-trifluoromethylphenyl)borate (TFPB) counter anions can facilitate the threading of dibenzylammonium (DBA(+)) ions through macrocycles in cases where the corresponding PF(6)(-) salts fail to exhibit complexation.

Klein und fein: Das auf SiO2 gebildete [2]Pseudorotaxan aus Dipropargylammonium‐tetrafluoroborat und dem Kronenether [21]Krone‐7 wurde in einem Kugelmahlverfahren mit 1,2,4,5‐Tetrazin‐Stoppern verschlossen (siehe Röntgenstrukturanalyse). Nach dieser effizienten lösungsmittelfreien Reaktion konnte das kleinste bekannte [2]Rotaxan in 81 % Ausbeute isoliert werden.

We describe a [2]rotaxane molecule that exhibits distinct signals in its (1)H NMR spectra upon the complexation of physiologically important Li(+), Na(+), Mg(2+) and Ca(2+) ions; thus, the identification of these metal ions in solution is possible from the analysis of a single (1)H NMR spectrum of a single molecular sensor.

Herein we report an easy-to-synthesize [2]rotaxane, which incorporates two ionic monopyridinium stations and one 2,2'-bipyridine station as the shaft of the dumbbell-shaped component and a bis-p-xylyl[26]crown-6 (BPX26C6) unit as the macrocyclic component. In this molecular shuttle, the BPX26C6 unit can be docked selectively on either the central 2,2'-bipyridine station or one of the two terminal pyridinium stations, and subsequently, returned to its shuttling molecular motion through the in situ addition of simple reagents (acid/base or metal ion/metal-ion-complexing ligand pairs).

A system based on a molecular cage, in which bisdiazonium, bispyridinium, and anthraquinone guests can be complexed to the host sequentially through the application of suitable stimuli, is reported.