calixarenes and imidazole

In this tutorial review we discuss imidazolium receptors for anion recognition and recent contributions between 2006-2009 are reviewed according to target analytes, such as ATP and DNA, as well as structural classification, including cage type imidazoliums, imidazolium calixarenes, ferrocenyl imidazoliums, chiral systems, fluorescent or colorimetric imidazoliums, imidazolium cyclophane, nano assembled structures, bile acid-imidazolium, and tripodal-imidazolium systems.

Topics: Anions; Calixarenes; Ferrous Compounds; Fluorescent Dyes; Imidazoles; Nanostructures

Supramolecular receptors such as water-soluble calixarenes are in development as 'molecular glues' for protein assembly. Here, we obtained cocrystals of sulfonato-calix[6]arene (sclx

Topics: Arginine; Binding Sites; Calixarenes; Crystallography, X-Ray; Cytochromes c; Imidazoles; Lysine; Models, Molecular; Protein Unfolding; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins

Neutral tetrakis(methylimidazole) (1) and the novel cationic tetrakis(methylimidazolium) (2) calixarenes have been prepared and their solid-state and solution behaviour examined. The neutral imidazole forms a mono-zwitterion at elevated temperature, a feature that has been observed both in solution and in the solid-state. The cationic imidazolium exhibits a range of hydrogen bond interactions with anions, with the titration curves upon binding to basic anions suggesting sequential binding to both the upper and lower rims.

Topics: Anions; Calixarenes; Crystallography, X-Ray; Imidazoles; Methylation; Models, Molecular; Molecular Structure; Protons

A new water-soluble pillar[5]arene containing ten imidazolium groups was prepared. It can be used as a stabilizer to fabricate gold nanoparticles smaller than 6 nm in water.

Topics: Calixarenes; Gold; Imidazoles; Nanoparticles; Particle Size; Quaternary Ammonium Compounds; Solubility; Water

Pyridinium and imidazolium bis-cations are shown to link calix[4]pyrrole anion complexes both in solution and in the solid state. This is accomplished by binding of the bis-cations to the electron-rich bowl shaped cavities formed by two separate calixpyrrole-anion complexes. These resulting sandwich-type structures provide a new way of organising calix[4]pyrrole anion complexes in space.

Topics: Anions; Calixarenes; Calorimetry; Cations; Crystallography, X-Ray; Imidazoles; Magnetic Resonance Spectroscopy; Models, Molecular; Porphyrins; Pyridinium Compounds

Coordination of Cu(I) to a tren unit that is covalently linked to a calix[6]arene has been explored. The resulting complex revealed itself very stable in solution under an inert atmosphere, but extremely sensitive to O2 in solution as well as in the solid state. Therefore, its binding properties towards non-redox ligands have been studied in detail. The electron-rich metal center displays moderate affinity for nitrilo ligands compared to the calix[6]tris-pyridine ligand. Indeed, the binding enthalpy with acetonitrile is only -30 kJ mol(-1), whereas it is -72 kJ mol(-1) with the tris-pyridine system. In contrast, CO binding is relatively strong due to important pi-back donation from the metal center, as evidenced by the CO stretch, which was found to be less energetic (2075 cm(-1)) than that measured for ligands based on aromatic donors such as imidazole or pyridine. The conformational and dynamic properties of this calix-system have also been studied in detail. With an empty cavity or with the very small CO guest-ligand, the calix-core undergoes partial self-inclusion leading to dissymmetrical conformations. In contrast, nitrilo ligands act as "shoe-trees" that maintain the calix-core in a C(3v) symmetrical cone conformation. Very interestingly, the variable T study relative to the ligand exchange process highlighted a two-step dissociative pathway, where Cu-N bond cleavage/formation is differentiated from the nitrilo guest expulsion/inclusion from/into the calixarene cavity.

Topics: Atmosphere; Binding Sites; Calixarenes; Carbon; Copper; Electrons; Imidazoles; Ligands; Molecular Conformation; Nitrogen; Organometallic Compounds; Oxidation-Reduction; Oxygen; Phenols; Pyridines; Solutions; Thermodynamics

The coordination of a first Zn(II) ion to a calix[6]arene presenting three imidazolyl arms at the small rim and three aniline moieties at the large rim allows the binding of a second Zn(II) ion while hosting a (H3O2)- unit in the aromatic cavity.

Topics: Aniline Compounds; Calixarenes; Cations, Divalent; Hydroxides; Imidazoles; Magnetic Resonance Spectroscopy; Molecular Structure; Organometallic Compounds; Phenols; Zinc