Publications by authors named "Andreea R Schmitzer"

35 Publications

Phenylethynylbenzyl-modified biguanides inhibit pancreatic cancer tumor growth.

Sci Rep 2021 05 10;11(1):9854. Epub 2021 May 10.

Département de Chimie-Faculté des Arts et des Sciences, Université de Montréal, 2900 Edouard Montpetit, Succursale Centre-Ville, CP 6128, Montreal, QC, H3C3J7, Canada.

We present the design and synthesis of a small library of substituted biguanidium salts and their capacity to inhibit the growth of pancreatic cancer cells. We first present their in vitro and membrane activity, before we address their mechanism of action in living cells and in vivo activity. We show that phenylethynyl biguanidium salts possess higher ability to cross hydrophobic barriers, improve mitochondrial accumulation and anticancer activity. Mechanistically, the most active compound, 1b, like metformin, activated AMPK, decreased the NAD/NADH ratio and mitochondrial respiration, but at 800-fold lower concentration. In vivo studies show that compound 1b significantly inhibits the growth of pancreatic cancer xenografts in mice, while biguanides currently in clinical trials had little activity.
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http://dx.doi.org/10.1038/s41598-021-87993-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8110578PMC
May 2021

Phytochemical- and Cyclodextrin-Based Pickering Emulsions: Natural Potentiators of Antibacterial, Antifungal, and Antibiofilm Activity.

Langmuir 2020 04 17;36(16):4317-4323. Epub 2020 Apr 17.

Université de Montréal, Département de Chimie, CP 6128 Succursale Centre-Ville, H3C3J7 Montréal, Québec, Canada.

We present self-assembled Pickering emulsions containing biocidal phytochemical oils (carvacrol and terpinen-4-ol) and β-cyclodextrin able to potentiate the antimicrobial and antibiofilm activity of miconazoctylium bromide. The carvacrol-containing emulsion is 2-fold more sensitive against and and highly active against , compared to the commercial cream containing miconazole nitrate. Moreover, this emulsion shows a synergistic effect against fungi, additive responses against bacteria, and remarkable staphylococcal biofilm eradication. These results are associated with membrane permeabilization, enzymes inhibition, and the accumulation of reactive oxygen species in microorganisms.
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http://dx.doi.org/10.1021/acs.langmuir.0c00314DOI Listing
April 2020

Anti-staphylococcal biofilm activity of miconazoctylium bromide.

Org Biomol Chem 2018 06;16(23):4288-4294

Department of Chemistry, University of Montreal, PO Box 6128, Succursale Centre-Ville Montreal, QC H3C 3J7, Canada.

We designed and synthesized miconazole analogues containing a substituted imidazolium moiety. The structural modification of the miconazole led to a compound with high potency to prevent the formation and disrupt bacterial biofilms, as a result of accumulation in the biofilm matrix, permeabilization of the bacterial membrane and generation of reactive oxygen species in the cytoplasm.
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http://dx.doi.org/10.1039/c8ob00897cDOI Listing
June 2018

Synthesis and Characterization of Biguanide and Biguanidium Surfactants for Efficient and Recyclable Application in the Suzuki-Miyaura Reaction.

ACS Omega 2018 Feb 13;3(2):1889-1896. Epub 2018 Feb 13.

Département de Chimie, Faculté des Arts et des Sciences, Université de Montréal, 2900 Edouard Montpetit, C.P. 6128 succursalle Centre Ville, H3C3J7 Montréal, Québec, Canada.

We report here the synthesis and thorough characterization of a new family of alkylbiguanides and alkylbiguanidium chlorides by H and C NMR and X-ray diffraction. Their critical micelle concentration was first determined by surface tension measurements. Hexylbiguanide was then studied as a surfactant in the micellar Suzuki-Miyaura cross-coupling reaction. The unexpected low reactivity of the system at high Pd/hexylbiguanide ratios was due to the change of the size and the shape of the aggregates, observed by transmission electron microscopy. The best catalytic activity was obtained for a 1:1 Pd/hexylbiguanide ratio for which the micellar conditions were conserved. Better results were obtained for several substrates, when compared to those previously obtained with metformin under the same reaction conditions. Higher yields and a better recyclability were obtained under micellar conditions with hexylbiguanide.
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http://dx.doi.org/10.1021/acsomega.7b01962DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6641416PMC
February 2018

Correction: Ultra-low fouling alkylimidazolium modified surfaces for the detection of HER2 in breast cancer cell lysates.

Analyst 2017 08;142(16):3011

Département de chimie, Université de Montréal, C.P. 6128 Succ. Centre-ville, Montreal, Quebec, H3C 3J7, Canada.

Correction for 'Ultra-low fouling methylimidazolium modified surfaces for the detection of HER2 in breast cancer cell lysates' by Alexandra Aubé et al., Analyst, 2017, 142, 2343-2353.
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http://dx.doi.org/10.1039/c7an90058aDOI Listing
August 2017

Ultra-low fouling alkylimidazolium modified surfaces for the detection of HER2 in breast cancer cell lysates [corrected].

Analyst 2017 06;142(13):2343-2353

Département de chimie, Université de Montréal, C.P. 6128 Succ. Centre-ville, Montreal, Quebec H3C 3J7, Canada.

We synthesized novel ultra-low fouling ionic liquids and demonstrated their use with surface plasmon resonance (SPR) sensing for the analysis of HER2 in breast cancer cell lysates. Whilst biomarkers are commonly detected in serum, this remains challenging for cancer diagnosis due to their low concentrations in circulation and in some cases, there is a poor correlation between serum and tissue concentrations. Therefore, a cell lysate constitutes an interesting biosample for cancer diagnosis and typing, which has been largely unexploited for chemical biosensing of cancer biomarkers. However, high fouling of surfaces in contact with the cell lysate and the absence of effective surface chemistry to prevent fouling are currently limiting biomarker analysis in cell lysates. To address this challenge, we report the synthesis of 1-(carboxyalkyl)-3-(12-mercaptododecyl)-1H-imidazolium ionic liquids with different anions (Br, BF, PF, ClO, and NTf) and ethyl and pentyl chains to form monolayers and analyse specific proteins from cell lysates. The most efficient ionic liquid monolayer, 1-(carboxyethyl)-3-(12-mercaptododecyl)-1H-imidazolium bromide, was able to eliminate the nonspecific adsorption (surface coverage of 2 ± 2 ng cm) of a concentrated cell lysate (protein concentration of ∼3.5 mg mL), which was significantly better than carboxy-PEG (surface coverage of 14 ± 7 ng cm), a benchmark monolayer commonly used to reduce nonspecific adsorption. These ionic liquid monolayers were modified with anti-HER2 and the detection of the HER2 breast cancer biomarker was carried out in crude breast cancer cell lysates, as shown with HER2-negative MCF-7 cells spiked with HER2 and with HER2 positive SK-BR-3 cells.
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http://dx.doi.org/10.1039/c7an00056aDOI Listing
June 2017

A field-deployed surface plasmon resonance (SPR) sensor for RDX quantification in environmental waters.

Analyst 2017 Jun 26;142(12):2161-2168. Epub 2017 May 26.

Department of Chemistry, Université de Montréal, C.P. 6128 Succ. Centre-Ville, Montreal, Quebec, H3C 3J7 Canada. and Centre for Self-Assembled Chemical Structures (CSACS), 801 Sherbrooke St. West, Montreal, Quebec, H3A 2K6 Canada.

A field-deployable surface plasmon resonance (SPR) sensor is reported for the detection of the energetic material (commonly termed explosives) 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) at ppb concentration in environmental samples. The SPR sensor was first validated under laboratory conditions with uncontaminated natural water samples spiked with known concentrations of RDX near the EPA limit of 2 ppb, which was then applied to monitor environmental samples collected in different downgradient wells near a grenade training range. The SPR sensor was finally tested on the field, where environmental samples were analysed on location in less than 90 minutes per well, which included the time to setup the equipment, sample the well and analyse the sample. The SPR analysis time was less than 45 minutes for equilibration, recalibration and measuring the water sample. Results obtained with the SPR sensors were cross-validated with the standard HPLC method (EPA method 8330b), and they showed good agreement with an accuracy within less than 1.6 ppb for analysis at the sampling sites, and with the relative standard deviation (RSD) better than 20% for field and laboratory measurements. The SPR sensor worked in a range of environmental conditions, including operation from about 0 °C to nearly 30 °C. The instrument was easily deployed near the sampling site using motor vehicles under summer conditions (Lab-in-a-Jeep) and using a sled under winter conditions (Lab-on-a-sled), showcasing the field deployability of the RDX SPR sensor and the possibility of continuously monitoring RDX in the environment.
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http://dx.doi.org/10.1039/c7an00216eDOI Listing
June 2017

Adaptation of a bacterial membrane permeabilization assay for quantitative evaluation of benzalkonium chloride as a membrane-disrupting agent.

Medchemcomm 2017 Jul 2;8(7):1408-1413. Epub 2017 May 2.

Département de Chimie , Université de Montréal , CP 6128, Succ. Centre Ville , Montréal (Québec) , Canada . Email:

We describe the use of the -nitrophenyl-β-galactoside (ONPG) assay developed by Lehrer to which a new mathematical data treatment was applied. In this simplified assay, only one enzymatic assay is needed to provide direct evidence of the kinetics of membrane permeabilization induced by different concentrations of benzalkonium chloride (). Analysis of the data obtained from the revised ONPG assay with our adapted mathematical formula indicates that induces permeabilization of the bacterial outer and inner membranes in a two-step process. The two effective concentration (EC) values obtained in this study, combined with the results from an outer membrane permeabilization assay, suggest that the two steps observed in the permeabilization process are related to the two different bacterial membranes. We show that membrane permeabilization occurs very fast upon the addition of bacterial cells to the solutions and demonstrate that sub-lethal concentrations of disturb the integrity of the Gram-negative bacterial membranes. Overall, our work broadens our knowledge on the mode of action of on bacterial cells and emphasizes that , and quaternary ammonium compounds in general, should not be used at sub-lethal concentrations in order to lower the risk of bacterial tolerance and resistance to antibiotics.
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http://dx.doi.org/10.1039/c7md00113dDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6072009PMC
July 2017

Investigation of Classical Organic and Ionic Liquid Cosolvents for Early-Stage Screening in Fragment-Based Inhibitor Design with Unrelated Bacterial and Human Dihydrofolate Reductases.

Assay Drug Dev Technol 2017 May/Jun;15(4):141-153. Epub 2017 Apr 20.

1 Département de Biochimie, Université de Montréal , Québec, Canada .

Drug design by methods such as fragment screening requires effective solubilization of millimolar concentrations of small organic compounds while maintaining the properties of the biological target. We investigate four organic solvents and three 1-butyl-3-methylimidazolium (BMIm)-based ionic liquids (ILs) as cosolvents to establish conditions for screening two structurally unrelated dihydrofolate reductases (DHFRs) that are prime drug targets. Moderate concentrations (10%-15%) of cosolvents had little effect on inhibition of the microbial type II R67 DHFR and of human DHFR (hDHFR), while higher concentrations of organic cosolvents generally decreased activity of both DHFRs. In contrast, a specific IL conserved the activity of one DHFR, while severely reducing the activity of the other, and vice versa, illustrating the differing effect of ILs on distinct protein folds. Most of the cosolvents investigated preserved the fold of R67 DHFR and had little effect on binding of the cofactor NADPH, but reduced the productive affinity for its substrate. In contrast, cosolvents resulted in modest structural destabilization of hDHFR with little effect on productive affinity. We conclude that the organic cosolvents, methanol, dimethylformamide, and dimethylsulfoxide, offer the most balanced conditions for early-stage compound screening as they maintain sufficient biological activity of both DHFRs while allowing for compound dissolution in the millimolar range. However, IL cosolvents showed poor capacity to solubilize organic compounds at millimolar concentrations, mitigating their utility in early-stage screening. Nonetheless, ILs could provide an alternative to classical organic cosolvents when low concentrations of inhibitors are used, as when characterizing higher affinity inhibitors.
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http://dx.doi.org/10.1089/adt.2016.768DOI Listing
March 2018

Metal-Organic Synthetic Transporters (MOST): Efficient Chloride and Antibiotic Transmembrane Transporters.

Chemistry 2017 May 7;23(26):6441-6451. Epub 2017 Apr 7.

Département de Chimie, Université de Montréal, C. P. 6128 Succursale Centre-Ville, Montréal, Québec, H3C 3J7, Canada.

We present the synthesis of two functionalized 2,4,7-triphenylbenzimidazole ligands and demonstrate the formation of their respective metal assemblies in phospholipid membranes. Anion transport experiments demonstrate the formation of metal-organic synthetic transporters (MOST) directly in phospholipid membranes. The formation of MOST in phospholipid membranes results in efficient architectures for chloride transport. We also demonstrate the insertion of these ligands and the formation of their metal-organic assemblies in bacterial membranes; the use of MOST makes the membranes of resistant bacteria more permeable to antibiotics. We also demonstrate that a combination of MOST with tetracycline lowers the sensitivity of resistant bacteria to tetracycline by 60-fold.
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http://dx.doi.org/10.1002/chem.201700847DOI Listing
May 2017

Strong antibacterial properties of anion transporters: a result of depolarization and weakening of the bacterial membrane.

J Med Chem 2015 Mar 25;58(5):2358-66. Epub 2015 Feb 25.

Département de Chimie, Université de Montréal , CP 6128 Succursale Centre Ville, H3C 3J7, Montreal, Quebec, Canada.

The development of low molecular weight anionophores is an emerging topic in chemistry, as the need for these compounds increases with the continuous discovery of pathologies involving anomalies in anion transport processes. Development of new concepts to initiate anion imbalance in living cells while fighting multidrug-resistant bacteria is a paramount topic. In this study, three series of compounds including N,N'-diphenylethynylbenzyl benzimidazolium salts (1 and 2), 1,1'-(pyridine-2,6-diyl)bis(3-(4-(phenylethynyl)benzyl)-1H-benzo[d]imidazol-3-ium) salts (3-5), and 1,1'-(pyridine-2,6-diylbis(methylene))bis(3-(4-(phenyl ethynyl)benzyl)-1H-benzo[d]imidazol-3-ium) salts (6-8) displaying high antimicrobial activity and low toxicity against human cells were designed, synthesized, and studied. The most potent compound displayed micromolar minimal inhibitory concentrations in different Gram-negative and Gram-positive bacteria, while its hemolytic activity remained around 10% or less, even after a prolonged period of exposure. The mechanism of action of these benzimidazolium salts on bacterial membrane was assessed by bioanalytical techniques including assays in model membrane liposomes, membrane depolarization studies, and scanning electron microscopy (SEM) in living bacteria.
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http://dx.doi.org/10.1021/jm501979fDOI Listing
March 2015

Asymmetric mutations in the tetrameric R67 dihydrofolate reductase reveal high tolerance to active-site substitutions.

Protein Sci 2015 Apr 26;24(4):495-507. Epub 2014 Dec 26.

Département de Biochimie, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montréal, Québec, H3C 3J7, Canada; PROTEO, the Québec Network for Protein Function, Structure and Engineering, Québec, Canada; CGCC, the Center for Green Chemistry and Catalysis, Montréal, Canada.

Type II R67 dihydrofolate reductase (DHFR) is a bacterial plasmid-encoded enzyme that is intrinsically resistant to the widely-administered antibiotic trimethoprim. R67 DHFR is genetically and structurally unrelated to E. coli chromosomal DHFR and has an unusual architecture, in that four identical protomers form a single symmetrical active site tunnel that allows only one substrate binding/catalytic event at any given time. As a result, substitution of an active-site residue has as many as four distinct consequences on catalysis, constituting an atypical model of enzyme evolution. Although we previously demonstrated that no single residue of the native active site is indispensable for function, library selection here revealed a strong bias toward maintenance of two native protomers per mutated tetramer. A variety of such "half-native" tetramers were shown to procure native-like catalytic activity, with similar KM values but kcat values 5- to 33-fold lower, illustrating a high tolerance for active-site substitutions. The selected variants showed a reduced thermal stability (Tm ∼12°C lower), which appears to result from looser association of the protomers, but generally showed a marked increase in resilience to heat denaturation, recovering activity to a significantly greater extent than the variant with no active-site substitutions. Our results suggest that the presence of two native protomers in the R67 DHFR tetramer is sufficient to provide native-like catalytic rate and thus ensure cellular proliferation.
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http://dx.doi.org/10.1002/pro.2602DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4380981PMC
April 2015

Catalytic anions embedded into avidin: importance of their chirality and the chiral environment on the stereocontrol of the aldol reaction.

J Org Chem 2014 Mar 3;79(6):2694-701. Epub 2014 Mar 3.

Department of Chemistry, Université de Montréal , C.P. 6128 Succursale Centre-ville, Montréal, Québec H3C 3J7, Canada.

Several catalytic anions bearing a pseudo-dipeptide scaffold, in combination with a biotinylated imidazolium cation, were prepared. The assembly of these salts with avidin resulted in the formation of stable biohybrid catalysts, active in ionic liquid/aqueous media for the aldol reaction. By using natural and non-natural amino alcohols as "side chains" for the proline derivative anion, we studied the cooperativity between the anion and its position in avidin. Taking advantage of the large freedom of movement of the anion inside avidin, we also investigated the substrate scope of this type of biohybrid catalyst.
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http://dx.doi.org/10.1021/jo5002406DOI Listing
March 2014

Transport of macrocyclic compounds across phospholipid bilayers by umbrella-rotaxanes.

Org Biomol Chem 2013 Sep;11(36):6023-8

Department of Chemistry-Université de Montréal, 2900 Edouard Montpetit, CP 6128 Succursalle Centre ville, Montréal, QC, Canada H3C3J7.

We report the synthesis and assembly of umbrella-rotaxanes with transmembrane transport properties. We describe their amphomorphism and validate their ability to penetrate and cross phospholipid bilayers. Furthermore we present the strategy to release the macrocyclic compound by enzymatic cleavage inside egg yolk phosphatidylcholine (EYPC) liposomes.
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http://dx.doi.org/10.1039/c3ob41209aDOI Listing
September 2013

Imidazolium-based ionic liquid surfaces for biosensing.

Anal Chem 2013 Jun 5;85(12):5770-7. Epub 2013 Jun 5.

Département de Chimie, Université de Montréal, C.P. 6128 Succ. Centre-Ville, Montreal, Quebec, Canada H3C 3J7.

Ionic liquid self-assembled monolayers (SAM) were designed and applied for binding streptavidin, promoting affinity biosensing and enzyme activity on gold surfaces of sensors. The synthesis of 1-((+)-biotin)pentanamido)propyl)-3-(12-mercaptododecyl)-imidazolium bromide, a biotinylated ionic liquid (IL-biotin), which self-assembles on gold film, afforded streptavidin sensing with surface plasmon resonance (SPR). The IL-biotin-SAM efficiently formed a full streptavidin monolayer. The synthesis of 1-(carboxymethyl)-3-(mercaptododecyl)-imidazoliumbromide, a carboxylated IL (IL-COOH), was used to immobilize anti-IgG to create an affinity biosensor. The IL-COOH demonstrated efficient detection of IgG in the nanomolar concentration range, similar to the alkylthiols SAM and PEG. In addition, the IL-COOH demonstrated low fouling in crude serum, to a level equivalent to PEG. The IL-COOH was further modified with N,N'-bis (carboxymethyl)-l-lysine hydrate to bind copper ions and then, chelate histidine-tagged biomolecules. Human dihydrofolate reductase (hDHFR) was chelated to the modified IL-COOH. By monitoring enzyme activity in situ on the SPR sensor, it was revealed that the IL-COOH SAM improved the activity of hDHFR by 24% in comparison to classical SAM. Thereby, IL-SAM has been synthesized and successfully applied to three important biosensing schemes, demonstrating the advantages of this new class of monolayers.
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http://dx.doi.org/10.1021/ac400386zDOI Listing
June 2013

Benzimidazolium-based synthetic chloride and calcium transporters in bacterial membranes.

Org Biomol Chem 2013 Feb 12;11(6):923-8. Epub 2012 Nov 12.

Department of Chemistry, Université de Montréal, Montréal, Québec, Canada, H3C 3J7.

Herein, we present the first example of a benzimidazolium-based artificial transmembrane chloride transporter and a synthetic calcium ionophore that can regulate intracellular calcium concentrations in bacteria.
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http://dx.doi.org/10.1039/c2ob26966jDOI Listing
February 2013

Asymmetric aldol reaction catalyzed by the anion of an ionic liquid.

J Org Chem 2012 Jun 17;77(11):4917-23. Epub 2012 May 17.

Department of Chemistry, Université de Montréal, C.P. 6128 Succursale Centre-ville, Montréal, Québec, H3C 3J7, Canada.

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.
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http://dx.doi.org/10.1021/jo300737uDOI Listing
June 2012

A molecular chalice with hydrophobic walls and a hydrophilic rim: self-assembly and complexation properties.

Chem Commun (Camb) 2011 Dec 2;47(48):12834-6. Epub 2011 Nov 2.

Department of Chemistry, Université de Montréal, 2900 Edouard Montpetit CP 6128 Succursalle Centre-ville, Montréal, Québec, Canada H3C3J7.

We describe the synthesis of a diphenylglycoluril/dibenzo-crown-6 molecular chalice, the self-assembly at the air/water interface and its complexation properties in solution and at the water/chloroform interface.
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http://dx.doi.org/10.1039/c1cc15125hDOI Listing
December 2011

Properties of ionic liquids on Au surfaces: non-conventional anion exchange reactions with carbonate.

Chem Commun (Camb) 2011 Oct 30;47(38):10644-6. Epub 2011 Aug 30.

Department of Chemistry, Université de Montréal, C.P. 6128 Succ. Centre-Ville, Montréal, QC, Canada.

A simple anion metathesis in diluted aqueous carbonate at room temperature affords 1-(12-mercaptododecyl)-3-methyl-imidazolium carbonate (MDMI-HCO(3)) from MDMI salts self-assembled on gold films and nanoparticles. The properties of MDMI-SAM differ from MDMI in solution, for which the anion exchange reaction does not proceed.
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http://dx.doi.org/10.1039/c1cc13914bDOI Listing
October 2011

Phase transitions of an ionic liquid self-assembled monolayer on Au.

Phys Chem Chem Phys 2011 Jul 31;13(25):12015-23. Epub 2011 May 31.

Département de Chimie, Université de Montréal, C. P. 6128 Succ. Centre-Ville, Montréal, Qc, Canada H3C 3J7.

The properties of a surface modified with an ionic liquid self-assembled monolayer (IL-SAM) can be tuned by simply changing the deposition temperature. Mid-IR, SERS, and molecular modelling demonstrated that 1-(12-mercaptododecyl)-3-methylimidazolium bromide (MDMIBr) exhibited a crystalline monolayer for deposition temperatures below 25 °C. Above 25 °C, the aliphatic chain collapsed into a disordered conformation. At 40 °C, another phase transition occurs due to the imidazolium group tilting parallel to the surface. Consequently, the wettability of IL-SAM was tuned over a broad range of contact angle (from 20° to nearly 40°) by varying the deposition temperature. Permeation of redox mediators to a Au electrode coated with MDMIBr strongly depends on the net charge of the redox mediator. Electron transfer was excellent for neutral and negatively charged redox mediators on electrodes coated with IL-SAM regardless of deposition temperature.
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http://dx.doi.org/10.1039/c1cp20827fDOI Listing
July 2011

Uncovering new properties of imidazolium salts: Cl- transport and supramolecular regulation of their transmembrane activity.

Chem Commun (Camb) 2011 Feb 3;47(6):1788-90. Epub 2010 Dec 3.

Department of Chemistry, Université de Montréal, 2900 Edouard Montpetit CP 6128 Succursalle Centre-ville, Montréal, Québec, Canada.

We report the Cl(-) transport activity for three imidazolium-based transporters. We present significant findings regarding the use of α-cyclodextrin and cucurbit[7]uril macrocycles to form inclusion complexes with these salts and to inhibit their membrane activity.
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http://dx.doi.org/10.1039/c0cc04280cDOI Listing
February 2011

Introduction of axial chirality in a planar aromatic ligand results in chiral recognition with DNA.

J Mol Recognit 2011 Mar-Apr;24(2):288-94

Department of Chemistry, Université de Montréal, C.P. 6128 Station Downtown, Montréal, Québec H3C 3J7, Canada.

Dimerization of a hydroxycarbazole produces an axially chiral biaryl, BICOL (2). One enantiomer (R)-2, is capable of enantioselective binding to different polymorphs of DNA. The biaryl (R)-2 was shown by fluorescence and circular dichroism to induce a shift of Z-DNA to B-DNA. The opposite enantiomer (S)-2 shows no specific binding. The significant difference in behaviour between the two enantiomers (S)-2 and (R)-2 is in line with molecular modelling studies which show two very different binding geometries between the enantiomers with each polymorph of DNA.
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http://dx.doi.org/10.1002/jmr.1055DOI Listing
June 2011

Highly recyclable chemo-/biocatalyzed cascade reactions with ionic liquids: one-pot synthesis of chiral biaryl alcohols.

Chemistry 2010 Jun;16(23):6748-51

Department of Chemistry, Université de Montréal, C.P. 6128 Succursale Centre-ville, Montréal, Québec, H3C 3J7, Canada.

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http://dx.doi.org/10.1002/chem.201000302DOI Listing
June 2010

N,N'-methylenediimidazolium salts: from self-assembly to an efficient DNAse protection system.

Chemistry 2010 Apr 12;16(15):4686-92. Epub 2010 Mar 12.

Department of Chemistry, Université de Montréal, C.P. 6128 Succursale Centre-ville, Montréal, Québec, H3C 3J7 (Canada), Fax: (+1) 514-343-7586.

We have developed N,N'-dialkylmethylenediimidazolium salts ([C(n)C(n)DIM][X]2) that self-organize into multilayered cationic vesicles and can interact with DNA. These preorganized systems form complexes with linear DNA and protect it from DNase I cleavage.
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http://dx.doi.org/10.1002/chem.200902794DOI Listing
April 2010

Formation of inclusion complexes between 1,1'-dialkyl-3,3'-(1,4-phenylene)bisimidazolium dibromide salts and cucurbit[7]uril.

J Phys Chem B 2009 Dec;113(50):16159-68

Department of Chemistry, Université de Montréal, C.P. 6128 Succursale Centre-ville, Montréal, Québec, H3C 3J7, Canada.

N,N'-Dialkyl-(1,4-phenylene)bisimidazolium salts form inclusion complexes with cucurbit[7]uril (CB[7]) with high association constants. The stoichiometry of the complexes depends on the alkyl chains and on the relative concentration of the imidazolium salt and CB[7]. The binding interactions of CB[7] with these bisimidazolium salts were studied experimentally by (1)H NMR, high resolution mass spectroscopy, and UV spectroscopy, and theoretically by semiempirical molecular modeling. Nonlinear regression analysis was used to calculate or estimate the binding parameters for the supramolecular inclusion complexes present in solution. The detailed study of the binding association of these imidazolium salts may allow us to understand the exact role of each recognition site in these salts and to assemble higher supramolecular complexes.
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http://dx.doi.org/10.1021/jp905495pDOI Listing
December 2009

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

J Phys Chem B 2009 Jul;113(28):9493-8

Department of Chemistry, Universite de Montreal, C.P. 6128 Succursale Centre-ville, Montreal, Quebec H3C 3J7, Canada.

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.
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http://dx.doi.org/10.1021/jp9034369DOI Listing
July 2009

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

Chemistry 2009 Jun;15(26):6327-31

Department of Chemistry, Université de Montréal, C.P. 6128 Succursale Centre-ville, Montréal, Québec, Canada.

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.
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http://dx.doi.org/10.1002/chem.200900763DOI Listing
June 2009

Study of the supramolecular cooperativity in the multirecognition mechanism of cyclodextrins/cucurbituril/disubstituted diimidazolium bromides.

J Phys Chem B 2008 Nov 18;112(45):14176-84. Epub 2008 Oct 18.

Department of Chemistry, Université de Montréal, C.P. 6128 Succursale Centre-ville, Montréal, Québec, H3C 3J7, Canada.

N, N'-Disubstituted methylenediimidazolium bromide salts substituted with two aromatic groups present two different binding sites. In the binary complexes with cyclodextrins (CDs) or cucurbit[7]uril (CB[7]), the macrocycle is always positioned on the external aromatic residues. In the ternary complexes, CB[7] is positioned around the diimidazolium cation, where the external aromatic residue is included in the CD's cavity. The unfavored position of the CB[7] on the cationic site in the ternary complex is the result of its cooperative supramolecular interaction with the cyclodextrin. The obtained ternary complexes possess different interfacial properties, compared to those of the binary complexes. We demonstrate these hypotheses by NMR spectroscopy, ESI-HRMS spectrometry, molecular modeling simulation, and surface tension measurements.
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http://dx.doi.org/10.1021/jp805990tDOI Listing
November 2008

Multiple equilibria in the complexation of dibenzylimidazolium bromide salts by cyclodextrins: toward controlled self-assembly.

J Phys Chem B 2008 Sep 13;112(35):11064-70. Epub 2008 Aug 13.

In aqueous solution, dibenzylimidazolium bromide salts form dimeric assemblies by T-stacking between an acidic proton of the imidazolium and the benzyl aromatic ring of another cation. This dimeric association can be disturbed by the addition of native cyclodextrins. The control of the majority species in solution can be made by the judicious choice of cyclodextrin concentration and its macrocycle size. The dimer is complexed directly by beta-cyclodextrin, whereas in the presence of alpha-cyclodextrin, the dimer is dissociated to form a 1:1 inclusion complex; at higher concentration, this 1:1 complex can dimerize.
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http://dx.doi.org/10.1021/jp803760dDOI Listing
September 2008

Dibenzylimidazolium halides: from complex molecular network in solid state to simple dimer in solution and in gas phase.

J Phys Chem A 2008 Jun 13;112(22):4996-5001. Epub 2008 May 13.

Department of Chemistry, Université de Montréal, C.P. 6128 Succursale Centre-ville, Montréal, Québec H3C 3J7, Canada.

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.
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http://dx.doi.org/10.1021/jp801172mDOI Listing
June 2008
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