Andreea R. Schmitzer

Support vector machines: development of QSAR models for predicting anti-HIV-1 activity of TIBO derivatives.

The tetrahydroimidazo[4,5,1-jk][1,4]benzodiazepinone (TIBO) derivatives, as non-nucleoside reverse transcriptase inhibitors, acquire a significant place in the treatment of the infections by the HIV. In the present paper, the support vector machines (SVM) are used to develop quantitative relationships between the anti-HIV activity and four molecular descriptors of 82 TIBO derivatives. The results obtained by SVM give good statistical results compared to those given by multiple linear regressions and artificial neural networks. The contribution of each descriptor to structure-activity relationships was evaluated. It indicates the importance of the hydrophobic parameter. The proposed method can be successfully used to predict the anti-HIV of TIBO derivatives with only four molecular descriptors which can be calculated directly from molecular structure alone.

Supramolecular effects involving the incorporation of guest substrates in imidazolium ionic liquid networks: Recent advances and future developments

The interest in ionic liquids (ILs) as green solvents has grown enormously in the last few years. ILs have been proved to be convenient and economical solvents due to their efficiencies, non-toxicities and recyclabilities. Logically, these new media are used in a wide range of organic reactions. Recent investigations of the physicochemical properties of imidazolium ILs suggest that they behave as polymeric supramolecules that cannot be seen as conventional solvent. Electrostatic, H-bonds and π-stacking interactions occur in imidazolium ILs. When various organic compounds are mixed with imidazolium ILs, ‘inclusion complexes’ are formed and complex supramolecular organisation is created. In other words, ILs can be seen as a pre-organised medium that can modify the molecular reactivity (selectivity, substrate discrimination, etc.) by the formation of ‘inclusion complexes’ between guests (reactive species) and the ‘host networks’ (ILs). This mini review is intended to describe the imidazolium IL organisation (aggregation properties, formation of ‘inclusion complexes’, etc.) and to underline some of the effects on the organic reactivity of the inclusion of the guest substrates in imidazolium ILs.

Thermoregulated microemulsions by cyclodextrin sequestration: a new approach to efficient catalyst recovery.

The combination of imidazolium surfactants with alpha-cyclodextrins (CDs, in green) was used as a control element in the thermoregulated aqueous olefin hydroformylation. The self-assembly of the imidazolium surfactants (red) favors the micellization process at high temperatures, whereas at lower temperatures the complexation of the surfactant monomers into the alpha-CDs is favored.

Asymmetric Aldol Reaction Catalyzed by the Anion of an Ionic Liquid

Herein we report the synthesis of a chiral imidazolium salt derived from trans-L-hydroxyproline and its applications as a catalyst for the asymmetric aldol reaction. By performing the aldol reaction in [Bmim]NTf(2) as a solvent, we report excellent isolated yields of the aldol product (up to 99%), as well as modest to excellent selectivities (dr superior to 99:1. ee up to 89%). Mechanistic insights and the origins of the selectivity of the aldol reaction are discussed on the basis of the results obtained with two catalytic imidazolium salts having different H-bonding potential.

Recognition of 1,4-Xylylene binding sites in polyimidazolium cations by cucurbit[7]uril: toward pseudorotaxane assembly.

The binding interactions between cucurbit[7]uril (CB[7]) and different polyimidazolium cations containing aromatic binding sites (1,4-xylylene units) were studied experimentally by 1D and 2D NMR, high-resolution mass spectrometry (HRMS), and fluorimetry, and, theoretically, by computed geometries and enthalpy changes. CB[7] was found to form [2]- and [3]-pseudorotaxanes with these cations by the inclusion of the internal 1,4-xylylene units.

Imidazolium-functionalized β-cyclodextrin as a highly recyclable multifunctional ligand in water

We describe here the synthesis and the catalytic properties of a novel dodecyl-imidazolium modified β-cyclodextrin as a self-assembled catalytic system (Fig. 1) in neat water for an effective Suzuki–Miyaura reaction. The introduction of the dodecyl-imidazolium motif on the primary face of the β-cyclodextrin allowed the development of a green highly recyclable catalytic system for reactions in an aqueous environment. We present the application of this system to the Suzuki–Miyaura coupling without the use of a co-solvent or stabilizing phosphine ligands in aqueous media. The catalytic system is highly recyclable, allowing the reuse of the palladium catalyst in subsequent catalytic runs without loss of activity.

An anion structure–activity relationship of imidazolium-based synthetic transporters

We have developed imidazolium-based salts as a new recognition motif with strong anionophoric properties across phospholipid bilayers. We present here factors intrinsic to the imidazolium salts that allow the modulation of their ionophoric properties. We also report the kinetic and thermodynamic parameters of the most active imidazolium salt.

Biologically active binaphthol-scaffolded imidazolium salts

This work describes the antimicrobial activity and selectivity for Gram-positive bacteria of imidazolium-functionalized binols, as a result of their insertion into the lipid membrane and alteration of its permeability. The most potent compound displayed micromolar minimal inhibitory concentrations against Gram-positive Bacillus thuringiensis and Listeria seeligeri. At these concentrations, the rate of survival after 24 hours of mammalian cells was superior to 90% of that measured in the absence of these compounds and its haemolysis percentage was only about 10%.

Dibenzylimidazolium Halides: From Complex Molecular Network in Solid State to Simple Dimer in Solution and in Gas Phase

1,3-Dibenzylimidazolium bromide has been synthesized and the nature of the interactions between cations and anions has been studied in the solid state, in solution and in the gas phase. The cohesion of the crystal is ensured by a combination of hydrogen bonds, and aromatic stacking interactions. In solution and in the gas phase, the supramolecular structural organization due to T-stacking is maintained to a great extent.

2,4,7-Triphenylbenzimidazole: the monomeric unit of supramolecular helical rod-like transmembrane transporters

We describe the ability of 2,4,7-triphenylbenzimidazole to form a robust self-assembly inside phospholipid bilayers. The 2,4,7-triphenylbenzimidazole monomers possess a planar structure and a lipophilicity that allow them to self-assemble into helicoidal rod-like aggregates promoting anionic diffusion via helical pathways on their aromatic exterior. Their potent anionophoric activity is demonstrated by very low EC50 values (70 μmol l−1).