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  1. Article ; Online: Stereoselective Processes Based on σ-Hole Interactions

    Paola Peluso / Victor Mamane

    Molecules, Vol 27, Iss 14, p

    2022  Volume 4625

    Abstract: The σ-hole interaction represents a noncovalent interaction between atoms with σ-hole(s) on their surface (such as halogens and chalcogens) and negative sites. Over the last decade, significant developments have emerged in applications where the σ-hole ... ...

    Abstract The σ-hole interaction represents a noncovalent interaction between atoms with σ-hole(s) on their surface (such as halogens and chalcogens) and negative sites. Over the last decade, significant developments have emerged in applications where the σ-hole interaction was demonstrated to play a key role in the control over chirality. The aim of this review is to give a comprehensive overview of the current advancements in the use of σ-hole interactions in stereoselective processes, such as formation of chiral supramolecular assemblies, separation of enantiomers, enantioselective complexation and asymmetric catalysis.
    Keywords chalcogen bond ; enantioselectivity ; enantioseparation ; halogen bond ; σ-hole ; noncovalent interaction ; Organic chemistry ; QD241-441
    Language English
    Publishing date 2022-07-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Molecular Dynamics Simulations of Amylose- and Cellulose-Based Selectors and Related Enantioseparations in Liquid Phase Chromatography

    Roberto Dallocchio / Alessandro Dessì / Barbara Sechi / Paola Peluso

    Molecules, Vol 28, Iss 21, p

    2023  Volume 7419

    Abstract: In the last few decades, theoretical and technical advancements in computer facilities and computational techniques have made molecular modeling a useful tool in liquid-phase enantioseparation science for exploring enantioselective recognition mechanisms ...

    Abstract In the last few decades, theoretical and technical advancements in computer facilities and computational techniques have made molecular modeling a useful tool in liquid-phase enantioseparation science for exploring enantioselective recognition mechanisms underlying enantioseparations and for identifying selector–analyte noncovalent interactions that contribute to binding and recognition. Because of the dynamic nature of the chromatographic process, molecular dynamics (MD) simulations are particularly versatile in the visualization of the three-dimensional structure of analytes and selectors and in the unravelling of mechanisms at molecular levels. In this context, MD was also used to explore enantioseparation processes promoted by amylose and cellulose-based selectors, the most popular chiral selectors for liquid-phase enantioselective chromatography. This review presents a systematic analysis of the literature published in this field, with the aim of providing the reader with a comprehensive picture about the state of the art and what is still missing for modeling cellulose benzoates and the phenylcarbamates of amylose and cellulose and related enantioseparations with MD. Furthermore, advancements and outlooks, as well as drawbacks and pitfalls still affecting the applicability of MD in this field, are also discussed. The importance of integrating theoretical and experimental approaches is highlighted as an essential strategy for profiling mechanisms and noncovalent interaction patterns.
    Keywords computational methods ; enantioselective recognition ; enantioseparation ; molecular dynamics ; polysaccharide-based selectors ; Organic chemistry ; QD241-441
    Subject code 612
    Language English
    Publishing date 2023-11-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Synthesis of “Click BOX” ligands and preliminary results on their application in the asymmetric copper catalysed Henry reaction of o-methoxybenzaldehyde

    Daniela Giunta, PhD / Antonio Arras / Paola Peluso / Maurizio Solinas

    Results in Chemistry, Vol 3, Iss , Pp 100122- (2021)

    2021  

    Abstract: Two new chiral “click BOX” ligands have been synthetised with high yields starting from commercially available dimethyl propargylmalonate and optically pure alkanolamines, followed by copper catalysed cycloaddition (CuAAC) and oxazoline ring formation. ... ...

    Abstract Two new chiral “click BOX” ligands have been synthetised with high yields starting from commercially available dimethyl propargylmalonate and optically pure alkanolamines, followed by copper catalysed cycloaddition (CuAAC) and oxazoline ring formation. Catalytic activity of the new ligands has been tested in the copper mediated Henry addition. The model reaction between nitromethane and o-anisaldehyde affords the related 1-(2-methoxyphenyl)-2-nitroethanol in high yields (up to 92%) and moderate enantioselectivities (up to 67% e.e.) under straightforward experimental conditions.
    Keywords Bisoxazoline ligand ; 1,2,3-Triazole ; Henry reaction ; Catalysis ; Copper ; Chemistry ; QD1-999
    Language English
    Publishing date 2021-01-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Channels with ordered water and bipyridine molecules in the porous coordination polymer {[Cu(SiF6)(C10H8N2)2]·2C10N2H8·5H2O}n

    Emmanuel Aubert / Abdelatif Doudouh / Paola Peluso / Victor Mamane

    Acta Crystallographica Section E: Crystallographic Communications, Vol 72, Iss 11, Pp 1654-

    2016  Volume 1658

    Abstract: The coordination polymer {[Cu(SiF6)(C10H8N2)2]·2C10H8N2·5H2O}n, systematic name: poly[[bis(μ2-4,4′-bipyridine)(μ2-hexafluoridosilicato)copper(II)] 4,4′-bipyridine disolvate pentahydrate], contains pores which are filled with water and 4,4′-bipyridine ... ...

    Abstract The coordination polymer {[Cu(SiF6)(C10H8N2)2]·2C10H8N2·5H2O}n, systematic name: poly[[bis(μ2-4,4′-bipyridine)(μ2-hexafluoridosilicato)copper(II)] 4,4′-bipyridine disolvate pentahydrate], contains pores which are filled with water and 4,4′-bipyridine molecules. As a result of the presence of these ordered species, the framework changes its symmetry from P4/mmm to P21/c. The 4,4′-bipyridine guest molecules form chains inside the 6.5 × 6.9 Å pores parallel to [100] in which the molecules interact through π–π stacking. Ordered water molecules form infinite hydrogen-bonded chains inside a second pore system (1.6 × 5.3 Å free aperture) perpendicular to the 4,4′-bipyridine channels.
    Keywords Porous coordination polymer ; adsorption ; hydrogen bonding ; π–π stacking ; copper(II) ; 4,4′-bipyridine ; crystal structure ; Chemistry ; QD1-999
    Language English
    Publishing date 2016-11-01T00:00:00Z
    Publisher International Union of Crystallography
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Exploring interaction modes between polysaccharide-based selectors and biologically active 4,4′-bipyridines by experimental and computational analysis

    Roberto Dallocchio / Alessandro Dessì / Barbara Sechi / Bezhan Chankvetadze / Sergio Cossu / Victor Mamane / Emmanuel Aubert / Carla Rozzo / Giuseppe Palmieri / Ylenia Spissu / Paola Peluso

    Journal of Chromatography Open, Vol 2, Iss , Pp 100030- (2022)

    2022  

    Abstract: In the last few years, chiral 4,4′-bipyridine derivatives have been developed for different applications in catalysis, enantioseparation science, supramolecular and theoretical chemistry by modulating the activity of the molecular system through the ... ...

    Abstract In the last few years, chiral 4,4′-bipyridine derivatives have been developed for different applications in catalysis, enantioseparation science, supramolecular and theoretical chemistry by modulating the activity of the molecular system through the introduction of specific substituents in the heteroaromatic scaffold. More recently, the biological activity of 2′-substituted-3,3′,5,5′-tetrachloro-2-iodo-4,4′-bipyridines has been explored in the field of transthyretin (TTR) fibrillogenesis inhibition, and the anticancer cytotoxicity of some derivatives is currently under systematic investigation. In this frame, the high-performance liquid chromatography (HPLC) enantioseparation of four atropisomeric 2,2′-disubstituted-4,4′-bipyridines (R, R’ = Ar, I), which contain multiple interaction sites, such as hydrogen bonding (HB) donors and acceptors, halogen bond (XB) donors, and π-extended electronic clouds, was explored by using n-hexane (Hex)/2-propanol (2-PrOH) 90:10 v/v as a mobile phase (MP), and eight chiral columns with coated and immobilized amylose- and cellulose-based selectors. The impact of subtle structural variations of analytes and selectors on their mutual intermolecular interactivity was evaluated in terms of retention (k) and selectivity (α) factors. On this basis, chromatographic analysis based on systematic screening of analytes and selectors was integrated with electrostatic potential (V) analysis and molecular dynamics (MD) simulations as computational techniques. The effect of temperature on retention, selectivity, and enantiomer elution order (EEO) of the analytes with coated and immobilized amylose tris(3,5-dimethylphenylcarbamate) was also considered by comparing the variation of the thermodynamic profile associated with each enantioseparation. Chromatographic responses proved to be strictly dependent on specific regions within the analyte, and functions of different interactions sites of the analytes as the structure of the chiral selector changes were significantly disclosed.
    Keywords Bipyridines ; Electrostatic potential ; Enantioseparation ; High-performance liquid chromatography ; Molecular dynamics ; Polysaccharide-based chiral stationary phases ; Analytical chemistry ; QD71-142
    Subject code 540
    Language English
    Publishing date 2022-11-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Rational Design, Synthesis, Characterization and Evaluation of Iodinated 4,4′-Bipyridines as New Transthyretin Fibrillogenesis Inhibitors

    Alessandro Dessì / Paola Peluso / Roberto Dallocchio / Robin Weiss / Giuseppina Andreotti / Mariateresa Allocca / Emmanuel Aubert / Patrick Pale / Victor Mamane / Sergio Cossu

    Molecules, Vol 25, Iss 2213, p

    2020  Volume 2213

    Abstract: The 3,3′,5,5′-tetrachloro-2-iodo-4,4′-bipyridine structure is proposed as a novel chemical scaffold for the design of new transthyretin (TTR) fibrillogenesis inhibitors. In the frame of a proof-of-principle exploration, four chiral 3,3′,5,5′-tetrachloro- ... ...

    Abstract The 3,3′,5,5′-tetrachloro-2-iodo-4,4′-bipyridine structure is proposed as a novel chemical scaffold for the design of new transthyretin (TTR) fibrillogenesis inhibitors. In the frame of a proof-of-principle exploration, four chiral 3,3′,5,5′-tetrachloro-2-iodo-2′-substituted-4,4′- bipyridines were rationally designed and prepared from a simple trihalopyridine in three steps, including a Cu-catalysed Finkelstein reaction to introduce iodine atoms on the heteroaromatic scaffold, and a Pd-catalysed coupling reaction to install the 2′-substituent. The corresponding racemates, along with other five chiral 4,4′-bipyridines containing halogens as substituents, were enantioseparated by high-performance liquid chromatography in order to obtain pure enantiomer pairs. All stereoisomers were tested against the amyloid fibril formation (FF) of wild type (WT)-TTR and two mutant variants, V30M and Y78F, in acid mediated aggregation experiments. Among the 4,4′-bipyridine derivatives, interesting inhibition activity was obtained for both enantiomers of the 3,3′,5,5′-tetrachloro-2′-(4-hydroxyphenyl)-2-iodo-4,4′-bipyridine. In silico docking studies were carried out in order to explore possible binding modes of the 4,4′-bipyridine derivatives into the TTR. The gained results point out the importance of the right combination of H-bond sites and the presence of iodine as halogen-bond donor. Both experimental and theoretical evidences pave the way for the utilization of the iodinated 4,4′-bipyridine core as template to design new promising inhibitors of TTR amyloidogenesis.
    Keywords bipyridines ; docking ; fibril formation ; halogen bond ; misfolding inhibition ; transthyretin ; Organic chemistry ; QD241-441
    Subject code 540
    Language English
    Publishing date 2020-05-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Factors Impacting σ- and π-Hole Regions as Revealed by the Electrostatic Potential and Its Source Function Reconstruction

    Carlo Gatti / Alessandro Dessì / Roberto Dallocchio / Victor Mamane / Sergio Cossu / Robin Weiss / Patrick Pale / Emmanuel Aubert / Paola Peluso

    Molecules, Vol 25, Iss 4409, p

    The Case of 4,4′-Bipyridine Derivatives

    2020  Volume 4409

    Abstract: Positive electrostatic potential ( V ) values are often associated with σ- and π-holes, regions of lower electron density which can interact with electron-rich sites to form noncovalent interactions. Factors impacting σ- and π-holes may thus be monitored ...

    Abstract Positive electrostatic potential ( V ) values are often associated with σ- and π-holes, regions of lower electron density which can interact with electron-rich sites to form noncovalent interactions. Factors impacting σ- and π-holes may thus be monitored in terms of the shape and values of the resulting V . Further precious insights into such factors are obtained through a rigorous decomposition of the V values in atomic or atomic group contributions, a task here achieved by extending the Bader–Gatti source function (SF) for the electron density to V . In this article, this general methodology is applied to a series of 4,4′-bipyridine derivatives containing atoms from Groups VI (S, Se) and VII (Cl, Br), and the pentafluorophenyl group acting as a π-hole. As these molecules are characterized by a certain degree of conformational freedom due to the possibility of rotation around the two C–Ch bonds, from two to four conformational motifs could be identified for each structure through conformational search. On this basis, the impact of chemical and conformational features on σ- and π-hole regions could be systematically evaluated by computing the V values on electron density isosurfaces ( V S ) and by comparing and dissecting in atomic/atomic group contributions the V S maxima ( V S,max ) values calculated for different molecular patterns. The results of this study confirm that both chemical and conformational features may seriously impact σ- and π-hole regions and provide a clear analysis and a rationale of why and how this influence is realized. Hence, the proposed methodology might offer precious clues for designing changes in the σ- and π-hole regions, aimed at affecting their potential involvement in noncovalent interactions in a desired way.
    Keywords atomic group contributions ; bipyridines ; chalcogen bond ; electrostatic potential ; halogen bond ; σ-hole ; Organic chemistry ; QD241-441
    Subject code 541
    Language English
    Publishing date 2020-09-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Enantioseparation of 5,5′-Dibromo-2,2′-Dichloro-3-Selanyl-4,4′-Bipyridines on Polysaccharide-Based Chiral Stationary Phases

    Paola Peluso / Alessandro Dessì / Roberto Dallocchio / Barbara Sechi / Carlo Gatti / Bezhan Chankvetadze / Victor Mamane / Robin Weiss / Patrick Pale / Emmanuel Aubert / Sergio Cossu

    Molecules, Vol 26, Iss 221, p

    Exploring Chalcogen Bonds in Liquid-Phase Chromatography

    2021  Volume 221

    Abstract: The chalcogen bond (ChB) is a noncovalent interaction based on electrophilic features of regions of electron charge density depletion (σ-holes) located on bound atoms of group VI. The σ-holes of sulfur and heavy chalcogen atoms (Se, Te) (donors) can ... ...

    Abstract The chalcogen bond (ChB) is a noncovalent interaction based on electrophilic features of regions of electron charge density depletion (σ-holes) located on bound atoms of group VI. The σ-holes of sulfur and heavy chalcogen atoms (Se, Te) (donors) can interact through their positive electrostatic potential ( V ) with nucleophilic partners such as lone pairs, π-clouds, and anions (acceptors). In the last few years, promising applications of ChBs in catalysis, crystal engineering, molecular biology, and supramolecular chemistry have been reported. Recently, we explored the high-performance liquid chromatography (HPLC) enantioseparation of fluorinated 3-arylthio-4,4′-bipyridines containing sulfur atoms as ChB donors. Following this study, herein we describe the comparative enantioseparation of three 5,5′-dibromo-2,2′-dichloro-3-selanyl-4,4′-bipyridines on polysaccharide-based chiral stationary phases (CSPs) aiming to understand function and potentialities of selenium σ-holes in the enantiodiscrimination process. The impact of the chalcogen substituent on enantioseparation was explored by using sulfur and non-chalcogen derivatives as reference substances for comparison. Our investigation also focused on the function of the perfluorinated aromatic ring as a π-hole donor recognition site. Thermodynamic quantities associated with the enantioseparation were derived from van’t Hoff plots and local electron charge density of specific molecular regions of the interacting partners were inspected in terms of calculated V . On this basis, by correlating theoretical data and experimental results, the participation of ChBs and π-hole bonds in the enantiodiscrimination process was reasonably confirmed.
    Keywords bipyridines ; chalcogen bond ; electrostatic potential ; enantioseparation ; high-performance liquid chromatography ; polysaccharide-based chiral stationary phases ; Organic chemistry ; QD241-441
    Subject code 540 ; 541
    Language English
    Publishing date 2021-01-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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