A Semiflexible Tetrahydrazone Macrocycle for Binding of Pyrophosphate and Smaller Anions.

Macrocyclization has proven to be a useful design strategy in the development of efficient anion receptors. In addition to the ring size, the overall preorganization due to structural rigidity is key. To explore this in the context of developing an efficient pyrophosphate receptor, three macrocycles featuring a 26-membered interior ring size and similar H-bonding motifs have been synthesized, and their anion binding ability has been investigated.

A 4-state acid-base controlled molecular switch based on a host-guest system.

A novel Zn funnel complex that presents three phenol functions within a calix[6]arene macrocycle is described. Host-guest studies, monitored by H NMR spectroscopy, evaluate the impact of the replacement of three anisole moieties present in a previously described system with phenols. It is now shown that the dicationic complex is responsive to anions, whereas deprotonation of one phenol unit completely inhibits any hosting response.

Tuning the Fluorescence Through Reorientation of the Axle in Calix[6]arene-Based Pseudorotaxanes.

This work describes a calix[6]arene-based wheel that binds, in non-polar media, a stilbazolium salt to yield a mixture of pseudorotaxane orientational isomers. The isomer's abundance ratio evolves with time and can be reversibly tuned by adjusting the temperature. The spectroscopic properties, and notably the emission spectrum, of the bound guest depend on its orientation inside the non-palindromic wheel, suggesting such a system as a switch with spectroscopic readout.

"Two-Story" Calix[6]arene-Based Zinc and Copper Complexes: Structure, Properties, and O Binding.

A new "two-story" calix[6]arene-based ligand was synthesized, and its coordination chemistry was explored. It presents a tren cap connected to the calixarene small rim through three amido spacers. X-ray diffraction studies of its metal complexes revealed a six-coordinate Zn complex with all of the carbonyl groups of the amido arms bound and a five-coordinate Cu complex with only one amido arm bound.

Immobilization of Monolayers Incorporating Cu Funnel Complexes onto Gold Electrodes. Application to the Selective Electrochemical Recognition of Primary Alkylamines in Water.

The immobilization of a copper calix[6]azacryptand funnel complex on gold-modified electrodes is reported. Two different methodologies are described. One is based on alkyne-terminated thiol self-assembled monolayers.

Selective recognition of neutral guests in an aqueous medium by a biomimetic calix[6]cryptamide receptor.

The design of artificial receptors that can efficiently work in water is a challenging research area. A possible biomimetic approach for the elaboration of such receptors consists of associating a hydrophobic cavity with a polar polyfunctional binding site. On this basis, a hydrophilic calix[6]cryptamide decorated with oligo(ethylene glycol) units (i.

Supramolecular assistance for the selective demethylation of calixarene-based receptors.

The selective demethylation of methoxy groups of several multifunctionalized 1,3,5-trimethoxycalix[6]arene-based receptors has been achieved. It is shown in this study that the best reagent is trimethylsilyl iodide (TMSI) and that the conformation adopted by the calixarene core is crucial for both the selectivity and the efficiency of the process. A key feature appears to be the "in" or "out" orientation of the methoxy substituents relative to the macrocyclic cavity.