Immaculada Dinarès

Imidazolium ionic liquids: A simple anion exchange protocol

An efficient and simple protocol was developed to obtain quantitative iodide or bromide exchange for a broad range of anions in imidazolium ionic liquids. Selected anions were loaded in an anion exchange resin using two different procedures and were then used to provide a pure convenient ion pair.

Bis(imidazolium)−Calix[4]arene Receptors for Anion Binding†

Efficient access to the bis(imidazolyl)calixarene 2 and dicationic bis(imidazolium) salts 1a,b x 2X directly bonded to the upper rim of calixarene structure has been reported. Anion binding properties of the new receptors were studied by 1H NMR spectroscopic methods. Bis(N-butylimidazolium) dication 1a exhibited the best recognition properties toward carboxylate anions with a 1:1 receptor-anion binding stoichiometry, whereas the presence of a bulky group such as isopropyl (1b) increased the difficulty of both imidazolium moieties to be able to support the association with the same single anion.

A simple halide-to-anion exchange method for heteroaromatic salts and ionic liquids.

A broad and simple method permitted halide ions in quaternary heteroaromatic and ammonium salts to be exchanged for a variety of anions using an anion exchange resin (A− form) in non-aqueous media. The anion loading of the AER (OH− form) was examined using two different anion sources, acids or ammonium salts, and changing the polarity of the solvents. The AER (A− form) method in organic solvents was then applied to several quaternary heteroaromatic salts and ILs, and the anion exchange proceeded in excellent to quantitative yields, concomitantly removing halide impurities. Relying on the hydrophobicity of the targeted ion pair for the counteranion swap, organic solvents with variable polarity were used, such as CH3OH, CH3CN and the dipolar nonhydroxylic solvent mixture CH3CN:CH2Cl2 (3:7) and the anion exchange was equally successful with both lipophilic cations and anions.

A general halide-to-anion switch for imidazolium-based ionic liquids and oligocationic systems using anion exchange resins (A− form)

Further studies on the application of an AER (A(-) form) method broadened the anion exchange scope of representative ionic liquids and bis(imidazolium) systems. Depending on the hydrophobicity nature of the targeted imidazolium species and counteranions, different organic solvents were used to swap halides for assorted anions, proceeding in excellent to quantitative yields.

Imidazolium-Based Receptors

Abstract Imidazolium salts, which constitute a varied pool of charged chemical entities, are situated at the crossroads of multidisciplinary fields in chemistry because of their incorporation in a broad array of molecular systems. Imidazolium functionality has emerged as a privileged structural motif for the design of specifically tailored artificial receptors for anion recognition and sensing. The specific focus of this chapter is to give an overview of these positively charged systems, with a brief discussion of the chemistry of imidazolium quaternary salts. Representative examples of imidazolium-based systems have been ordered according to their molecular frameworks and include cyclophanes, protophanes, and calixarenes as well as a tripodal molecular platform. The final section concerns miscellaneous molecular systems with a variety of coexisting topologies as well as a number of subunits, each with its own specific properties. These systems have applications in anion recognition chemistry leaning toward nanoscience.

Identification of Novel Indanylsulfonamide Guanylhydrazones as Potent 5-HT6 Serotonin Receptor Antagonists

Changing the N,N-(dimethylamino)ethyl side chain in the N-[3-(aminoethyl)inden-5-yl]sulfonamide 5-HT(6) serotonin receptor agonists 1 by a conformationally rigid guanylhydrazone moiety at the indene 3-position led to the identification of the title indanylguanylhydrazones 6, which exhibited excellent binding affinities and an antagonistic response at the 5-HT(6) receptor, with K(i) and IC(50) values in the nanomolar range (K(i) >or= 1.2 nM, IC(50) >or= 47 nM, and I(max) <or= 173%).

Pyridinium azolate betaines and their derivatives: a new class of antiprotozoal agents

Abstract N -azolylpyridinium salts 1 and several betaines of pyridinium azolate 2 have been synthetized in order to study their in vitro antiprotozoal activity. A careful 1 H and 13 C-NMR study has been carried out in order to characterize the different compounds. A significant growth inhibition of Trypanosoma cruzi and especially Leishmania donovani was observed with the N -benzimidazolyl-pyridinium derivatives. When tested in vivo against Leishmania donovani , compounds 9 and 40 have had a much greater reducing effect in the parasite than that of the reference drug (glucantime).

A novel class of aza-analogues of sesquifulvalene with a betaine character: 1-alkyl-4-(azolylidene)-1,4-dihydropyridines

The first synthesis of 1-alkyl-4-(azolylidene)-1,4-dihydropyridines(2A)↔(2B) is described; their physicochemical properties clearly indicate a significant contribution of the dipolar structure(2B) to the ground state of (2) and this has been confirmed by the X-ray crystal structure of 1-methyl-4-(benzimidazolylidene)-1,4-dihydropyridine(4a).

The betaine pool : molecular guests in medicinal chemistry and molecular hosts in supramolecular chemistry

Abstract The most relevant aspects of azolium(pyridinium)azolate betaines with a variety of spacers 1 is reviewed. An interdisciplinary approach to their chemistry is currently directed towards medicinal chemistry, supramolecular chemistry and advanced organic materials.

NMR studies of N-(benzimidazol-2-yl)pyridinium derivatives: QSAR with the anti-leishmanial activity and their carbon-13 NMR chemical shifts

Abstract Quantitative structure-activity — relationships between the in vitro anti-leishmanial activity of N -benzimidazolyl-2,4,6-triphenylpyridinium salts 6 and pyridinium benzimidazolate betaines 7 and their 13 C-NMR chemical shifts have been studied, in order to ascertain the influence of the benzimidazole substituents upon anti-leishmanial activity. The calculated 13 C-chemical shifts allow the selection of a representative subset of compounds. Several new N -benzimidazolylpyridinium derivatives 6 and 7 have been prepared. Among them, 5-methoxy-1-methylbenzimidazole 21 and 6-methoxy-1-methylbenzimidazole 22 derivatives have high anti-leishmanial activity in vitro and compound 22 shows an interesting activity in vivo although host toxicity is present.