Simonetta Orlandi

Concordia University Montreal, Montréal, Quebec, Canada

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Publications (23)52.62 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Three enantiopure fluorous thioureas featuring a free –NH2 group were synthesized by direct addition of aromatic isothiocyanates bearing a single n-C8F17 substituent in the ortho, meta and para position, respectively, to enantiopure (1R,2R)-1,2-diaminocyclohexane. The catalytic behavior of these bifunctional molecules was assessed in representative Michael-type reactions. The three fluorous thioureas performed similarly in all the reactions tested, thus showing that the position of the fluorous ponytail does not have a major influence on the catalytic behavior of this class of compounds. In particular, excellent enantioselectivities (up to 99% ee) and yields (up to 98%) were obtained for the addition of aliphatic aldehydes to maleimides to give α-substituted succinimides. Recyclability of these primary amine-based thioureas was found to be limited by the concurrent formation of imine-derivatives during the catalytic process, leading to a structural modification of the organic catalyst.
    ChemInform 06/2014; 45(22).
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    ABSTRACT: A new donor/acceptor (D-A) spiro dye (SCPDT1) featuring two bithiophene units, connected through an sp(3)-hybridized carbon atom, was prepared by a multistep synthetic sequence involving the convenient assembly of the spiro system under mild catalytic conditions. The photocurrent spectrum of dye-sensitized solar cells incorporating SCPDT1 covers the spectral region ranging from 350 to 700 nm and reaches a wide maximum of ∼80% in the 420-560 nm range. Power conversion efficiencies of up to 6.02% were obtained.
    Organic Letters 08/2013; · 6.14 Impact Factor
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    ABSTRACT: A novel trichromophoric assembly was synthesized, where two molecules of 7-alkoxy-4-methylcoumarin, acting as energy donors, were linked at a fixed distance and controlled geometry to an energy-acceptor bis(alkylaminostyryl) unit. Resonance energy transfer between the two different species was demonstrated by a careful spectroscopic analysis.
    Tetrahedron 04/2013; 69(13):2827–2833. · 2.80 Impact Factor
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    ABSTRACT: Lectin-carbohydrate interactions are the basis of many biological processes and essentially they constitute the language through which intercellular communications are codified. Thus they represent powerful tools in the examination and interpretation of changes that occur on cell surfaces during both physiological and, more importantly, pathological events. The development of optical techniques that exploit the unique properties of luminescent lanthanoid metal complexes in the investigation of lectin-carbohydrate recognition can foster research in the field of ratiometric biosensing and disease detection. Here we report the synthesis of a Tb3+-DO3A complex () bearing an α-d-mannose residue and the related study of binding affinity with concanavalin A (Con A) labeled with rhodamine-B-isothiocyanate (RITC-Con A). Luminescence spectroscopy and dynamic studies show changes in emission spectra that can be ascribed to a luminescence resonance energy transfer (LRET) from (donor) to RITC-Con A (acceptor). The binding constant value between the two species was found to be one order of magnitude larger than those previously reported for similar types of recognition. To the best of our knowledge this is the first example of the use of a pre-organized luminescent lanthanoid complex in the study of carbohydrate-protein interactions by LRET.
    Dalton Transactions 03/2013; · 4.10 Impact Factor
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    ABSTRACT: Highly versatile coordinating ligands are designed and synthesized with two β-diketonate groups linked at the carbon 3 through a phenyl ring. The rigid aromatic spacer is introduced in the molecules to orient the two acetylacetone units along different angles and coordination vectors. The resulting para, meta, and ortho bis-(3-acetylacetonate)benzene ligands show efficient chelating properties toward Cu(II) ions. In the presence of 2,2'-bipyridine, they promptly react and yield three dimers, 1, 2, and 3, with the bis-acetylacetonate unit in bridging position between two metal centers. X-ray single crystal diffraction shows that the compounds form supramolecular chains in the solid state because of intermolecular interactions. Each of the dinuclear complexes shows a magnetic behavior which is determined by the combination of structural parameters and spin polarization effects. Notably, the para derivative (1) displays a moderate antiferromagnetic coupling (J = -3.3 cm(-1)) along a remarkably long Cu···Cu distance (12.30 Å).
    Inorganic Chemistry 04/2012; 51(9):5409-16. · 4.59 Impact Factor
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    ABSTRACT: Cu(II) and a bis-β-diketone ligand generate a small constitutional dynamic library (CDL). The designed introduction of a well suited guest drives the self-sorting of the system toward a supramolecular triangle. Alternatively, the triangle self-assembly is templated by the same guest in a one-pot synthesis.
    Chemical Communications 02/2012; 48(25):3115-7. · 6.38 Impact Factor
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    ABSTRACT: A series of structurally related sensitizers containing fluorene as a π-conjugated central core have been synthesized, characterized, and applied in the development of dye-sensitized solar cells (DSSCs). The new electron donor (diphenylamine)−acceptor (cyanoacrylic acid) D-π-A molec-ular structures hold perfluoro-tert-butyl substituents in differ-ent positions. It is demonstrated that the fluorous substitution pattern remarkably affects the behavior of dyes as photo-sensitizers in DSSCs, leading to an improvement in the power conversion efficiencies with respect to analogous nonfluorous molecules. ■ INTRODUCTION The continuous growth of energy demand around the world and the environmental pollution resulting in global warming have led to a greater focus on research in renewable energy sources over the past decades. Contrary to the fossil fuels, solar energy is available profusely in most of the world's regions; still, it can be used for direct electricity production by means of photovoltaic and photoelectrochemical cells. In this frame dye-sensitized solar cells (DSSCs) are currently the most efficient and stable excitonic photocells, 1,2 offering several advantages over traditional silicon-based devices, notably, simplicity in fabrication and reduction in production costs. These unique features give the chance to develop DSSC technology even in countries with lower industrialization levels. The design of suitable photosensitizers remains one of the most important research topics in DSSCs with regard for improving their performance. 3 To this end a number of light-absorbing compounds with different molecular structures have been proposed and tested, 2 starting with Ru(II) polypyridyl complexes, which are still now one of the most successful class of photosensitizers. 4 However, the limited availability of Ru and possible environmental problems could limit its extensive application. Furthermore, these complexes are relatively expensive and hard to purify compared with organic sensitizers that can be obtained at reasonable cost and high purity grade through well-established synthetic techniques. Organic dyes present other potential advantages, including the huge diversity of molecular structures and high molar extinction coefficients, generally superior to those of Ru dyes (<20 000 M −1 cm −1). This allows using thinner spaced nanostructured oxide semiconductor films without losing light harvesting efficiency, a key factor in solid-state DSSC development. Another important aspect that is feasible to control with organic dyes is the chance to construct semitransparent and multicolor solar cells that can be used, for example, in power-producing windows. DSSCs with dyes that are transparent over a region of the visible spectrum would allow part of visible light to enter a building while converting the adsorbed portion of the solar radiation into electricity. Thus, this kind of cells can be the target of a high-value market segment. 5 Generally, metal-free organic photosensitizers possess molecular structures comprised of a donor part (D) and an acceptor counterpart (A) bridged by a π-conjugated link-age. 6−11 As a class of donors, triphenylamine (TPA) and its derivatives have shown promising applications in the develop-ment of photovoltaic devices, 12 whereas cyanoacetic acid moiety is one of the most used units as an electron acceptor/ anchoring group in the design of organic dyes for highly efficient DSSCs. 13 Irradiation of these dipolar molecules generates photoinduced intramolecular charge transfer states, which are able to inject electrons to the TiO 2 conduction band. The preferential orientation of the dye anchored to the TiO 2 surface not only improves charge injection but also keeps the photooxidized donor away from photoinjected electrons. This fact diminishes the deleterious back electron transfer process. Several dipolar metal-free dyes have been reported as sensitizers in DSSCs in recent years. 14−16 For this kind of dye, the absorption region responding to the solar spectrum is
  • Source
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    ABSTRACT: A series of structurally related sensitizers containing fluorene as a π-conjugated central core have been synthesized, characterized, and applied in the development of dye-sensitized solar cells (DSSCs). The new electron donor (diphenylamine)−acceptor (cyanoacrylic acid) D-π-A molec-ular structures hold perfluoro-tert-butyl substituents in differ-ent positions. It is demonstrated that the fluorous substitution pattern remarkably affects the behavior of dyes as photo-sensitizers in DSSCs, leading to an improvement in the power conversion efficiencies with respect to analogous nonfluorous molecules. ■ INTRODUCTION The continuous growth of energy demand around the world and the environmental pollution resulting in global warming have led to a greater focus on research in renewable energy sources over the past decades. Contrary to the fossil fuels, solar energy is available profusely in most of the world's regions; still, it can be used for direct electricity production by means of photovoltaic and photoelectrochemical cells. In this frame dye-sensitized solar cells (DSSCs) are currently the most efficient and stable excitonic photocells, 1,2 offering several advantages over traditional silicon-based devices, notably, simplicity in fabrication and reduction in production costs. These unique features give the chance to develop DSSC technology even in countries with lower industrialization levels. The design of suitable photosensitizers remains one of the most important research topics in DSSCs with regard for improving their performance. 3 To this end a number of light-absorbing compounds with different molecular structures have been proposed and tested, 2 starting with Ru(II) polypyridyl complexes, which are still now one of the most successful class of photosensitizers. 4 However, the limited availability of Ru and possible environmental problems could limit its extensive application. Furthermore, these complexes are relatively expensive and hard to purify compared with organic sensitizers that can be obtained at reasonable cost and high purity grade through well-established synthetic techniques. Organic dyes present other potential advantages, including the huge diversity of molecular structures and high molar extinction coefficients, generally superior to those of Ru dyes (<20 000 M −1 cm −1). This allows using thinner spaced nanostructured oxide semiconductor films without losing light harvesting efficiency, a key factor in solid-state DSSC development. Another important aspect that is feasible to control with organic dyes is the chance to construct semitransparent and multicolor solar cells that can be used, for example, in power-producing windows. DSSCs with dyes that are transparent over a region of the visible spectrum would allow part of visible light to enter a building while converting the adsorbed portion of the solar radiation into electricity. Thus, this kind of cells can be the target of a high-value market segment. 5 Generally, metal-free organic photosensitizers possess molecular structures comprised of a donor part (D) and an acceptor counterpart (A) bridged by a π-conjugated link-age. 6−11 As a class of donors, triphenylamine (TPA) and its derivatives have shown promising applications in the develop-ment of photovoltaic devices, 12 whereas cyanoacetic acid moiety is one of the most used units as an electron acceptor/ anchoring group in the design of organic dyes for highly efficient DSSCs. 13 Irradiation of these dipolar molecules generates photoinduced intramolecular charge transfer states, which are able to inject electrons to the TiO 2 conduction band. The preferential orientation of the dye anchored to the TiO 2 surface not only improves charge injection but also keeps the photooxidized donor away from photoinjected electrons. This fact diminishes the deleterious back electron transfer process. Several dipolar metal-free dyes have been reported as sensitizers in DSSCs in recent years. 14−16 For this kind of dye, the absorption region responding to the solar spectrum is
    The Journal of Physical Chemistry C 01/2012; · 4.84 Impact Factor
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    ABSTRACT: An extensive spectroscopic study is presented of two asymmetrically substituted fluorene dyes and of the related spiro dimers in both liquid and glassy solvents. Essential-state models are developed to accurately reproduce linear absorption and fluorescence spectra and their complex dependence on solvent polarity. The same models are exploited to quantitatively calculate fluorescence excitation and anisotropy spectra in rigid matrixes. Impressive red-edge effects observed for spiro dimers in glassy polar solvents are accurately reproduced and understood. Interchromophore interactions in the spiro dimers are very small, leading to marginal effects in absorption and fluorescence spectra, but they effectively promote energy transfer between the two chromophores, as best evidenced comparing anisotropy spectra of the substituted fluorenes and of corresponding spiro dimers dissolved in glassy solvent matrixes.
    The Journal of Physical Chemistry B 08/2011; 115(39):11420-30. · 3.61 Impact Factor
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    ABSTRACT: Novel C1-symmetric bis(oxazoline) ligands with a secondary binding sidearm were prepared in enantiomerically pure form in good yields, in only four steps starting from commercially available reagents. These new chiral ligands were tested in the enantioselective Mukaiyama aldol condensation between the trimethylsilyl keteneacetal of methyl isobutyrate and a non-chelating substrate such as benzaldehyde to afford the product in up to 55% ee.
    Journal of Organometallic Chemistry 01/2007; 692(11):2120-2124. · 2.00 Impact Factor
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    ABSTRACT: A three-component stereoselective reaction between an aldehyde, an amine and phenylacetylene to afford optically active propargyl amines in good yields was developed. The reaction is catalysed by copper complexes of enantiomerically pure bis-imines. The best results were obtained with imines readily prepared in very high yields from the commercially available binaphtyl diamine.A very simple experimental procedure at room temperature allowed to obtain optically active propargyl amines in very good yields and enantioselectivity up to 75%. The extremely simple methodology and the mild reaction conditions, as well as the possibility of a modular approach for developing new and more efficient bis-imine-based chiral ligands make the present methodology very attractive.Graphical abstractA three-component stereoselective reaction between an aldehyde, an amine and phenylacetylene to afford optically active propargyl amines in good yields was developed. The reaction is catalysed by copper complexes of enantiomerically pure bis-imines. The best results were obtained with imines readily prepared in very high yields from the commercially available binaphtyl diamine.A very simple experimental procedure at room temperature allowed to obtain optically active propargyl amines in very good yields and enantioselectivity up to 75%.
    Journal of Molecular Catalysis A Chemical 12/2006; 260:128-134. · 3.19 Impact Factor
  • Synfacts 06/2006; 2006(7):0682-0682.
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    ABSTRACT: The stereoselective addition of aryl- and alkylacetylene derivatives to imines was studied. The reaction is catalyzed by copper complexes of enantiomerically pure bisimines, readily prepared in very high yields from the commercially available binaphthyl diamine. A very simple experimental procedure allowed to obtain at room temperature optically active propargylamines in high yields and enantioselectivity. Interestingly, bisimine/copper(I) complexes were able to promote the direct, enantioselective, catalytic addition to imines of alkylacetylenes. The effects of catalyst loading and other reaction parameters on the stereochemical outcome of the transformation were investigated. The extremely convenient methodology, the mild reaction conditions, and the possibility of a modular approach for developing new and more efficient bisimine-based chiral ligands make the present methodology very attractive.
    The Journal of Organic Chemistry 04/2006; 71(5):2064-70. · 4.56 Impact Factor
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    ABSTRACT: Some galactose-oligopyridine conjugates were readily assembled by combining differently functionalized oligopyridines with peracetylated galactose derivatives. Variation in the structure of the components and of the linkers employed for their connection afforded adducts of different size, shape, and conformational mobility. Complexation of the bipyridine ligands with CuOTf and of the terpyridine ligand with Zn(OTf)2 afforded the corresponding peracetylated 2:1 and 1:1 complexes, respectively, as single species. Their structures were determined to be tetrahedral (Cu complexes) and trigonal-bipyramidal (Zn complex), on the basis of spectroscopic evidence. Removal of the acetyl protecting groups from the ligands afforded the corresponding polyols. The terpyridine-Zn(II) complex, unlike the bipyridine-Cu(I) complexes maintained their structures upon removal of the acetyl protecting groups.
    Tetrahedron 10/2005; 61(42):10048-10060. · 2.80 Impact Factor
  • Simonetta Orlandi, Federica Colombo, Maurizio Benaglia
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    ABSTRACT: For Abstract see ChemInform Abstract in Full Text.
    ChemInform 01/2005; 36(46).
  • Simonetta Orlandi, Maurizio Benaglia, Franco Cozzi
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    ABSTRACT: A mild, decarboxylative, aldol-type addition of malonic acid hemithioesters to aldehydes has been shown to occur with up to 39% enantioselectivity when the reaction was carried out in the presence of catalytic amounts of a Cu(II) salt, an enantiopure, tartaric acid-derived bis-benzimidazole and an achiral base.
    Tetrahedron Letters 06/2004; 45(8):1747-1749. · 2.40 Impact Factor
  • Annalen der Chemie und Pharmacie 05/2004; 2004(12):2669 - 2673. · 3.10 Impact Factor
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    ABSTRACT: For Abstract see ChemInform Abstract in Full Text.
    ChemInform 01/2004; 35(41).
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    ABSTRACT: Starting from the commercially available enantiopure (1S,2S)-2-amino-1-phenyl-1,3-propanediol novel enantiomerically pure benzimidazoles were prepared; N-alkylation gave chiral benzimidazolium salts, which were tested in asymmetric benzoin condensations. The synthesis of conceptually new, enantiomerically pure, C2 symmetric bis-thiazolium and bis-benzimidazolium salts was also developed. These new chiral heterocycles were employed as catalysts in the asymmetric dimerisation of benzaldehyde to give benzoin with moderate enantioselectivity.
    Tetrahedron Asymmetry 01/2003; 14(24):3827-3830. · 2.12 Impact Factor
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    ABSTRACT: Ignitor is the first ignition experiment conceived and designed on the basis of existing technologies and knowledge of plasma physics. Recent design activities within the Ignitor program have led to improve several of the main machine components. The present design of the central post allows for assembling and disassembling of the central transformer coils. The central post can take up the repulsive forces between the coils, this allows for greater freedom in programming the currents in the central coils and flexibility in controlling the plasma shape, the Plasma Chamber (PC) is supported through the ports by the Toroidal Field (TF) magnet structure. The new supports are designed to withstand the electromagnetic forces due to plasma disruptions and to allow the appropriate thermal expansions. The entire machine is cooled by helium gas down to 30 K, a system preferred to the hybrid helium–nitrogen cooling concept. Cooling the structural components at this temperature improves the role of wedging in withstanding the electromagnetic forces on the toroidal magnet. A metallic cryostat under vacuum was adopted. The vacuum reduces temperature gradients in the space immediately surrounding the machine, provides good thermal insulation, and second containment system for tritium.
    Fusion Engineering and Design - FUSION ENG DES. 01/2001; 58:815-820.