Ivo Starý

Publications (28)88.06 Total impact

• Article: Tetrathiafulvalene-Oligo(para-phenyleneethynylene) Conjugates: Formation of Multiple Mixed-Valence Complexes upon Electrochemical Oxidation.

  Sárka Lipnická, Martin Bělohradský, Viliam Kolivoška, Lubomír Pospíšil, Magdaléna Hromadová, Radek Pohl, Jana Vacek Chocholoušová, Jaroslav Vacek, Jan Fiedler, Irena G Stará, Ivo Starý
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  ABSTRACT: Short monodisperse oligo- (para-phenyleneethynylene) (pOPE) units bearing laterally attached tetrathio-substituted tetrathiofulvalene (TTF) units have been synthesised from functionalised aromatic building blocks by using the Sonogashira cross-coupling methodology. The unusual redox properties of these TTF-pOPE conjugates were observed by employing electrochemical methods, such as cyclic voltammetry and exhaustive electrolysis. We found that formally one half of the TTF units in the pOPE monomer 1, dimer 2, and trimer 3 (with 2, 4, and 6 TTF units, respectively) are electrochemically silent during the first-step oxidation at 0.49 V. We propose the formation of persistent mixed-valence complexes from the TTF and TTF(+) (.) units present in an equal ratio. Such mixed-valence dyads (single or multiple in the partially oxidised 1-3) exhibit an unusual stability towards oxidation until the potential of the second oxidation at 0.84 V is achieved. This finding suggests that below this potential the oxidation of the respective mix-valence complexes is extremely slow.
  Chemistry 03/2013; · 5.93 Impact Factor
• Article: A general approach to optically pure [5]-, [6]-, and [7]heterohelicenes.

  Jaroslav Žádný, Andrej Jančařík, Angelina Andronova, Michal Šámal, Jana Vacek Chocholoušová, Jaroslav Vacek, Radek Pohl, David Šaman, Ivana Císařová, Irena G Stará, Ivo Starý
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  ABSTRACT: Spiral staircases: A general method for the preparation of optically pure [5]-, [6]-, and [7]heterohelicenes is based on a Co(I) - or Ni(0) -catalyzed diastereoselective [2+2+2] cycloisomerization of centrally chiral triynes to deliver helicenes comprising two 2H-pyran rings. The configuration, which can be predicted, does not depend on helicene length or functional groups present.
  Angewandte Chemie International Edition 05/2012; 51(24):5857-61. · 13.45 Impact Factor
• Article: Helicene‐Based Phosphite Ligands in Asymmetric Transition‐Metal Catalysis: Exploring Rh‐Catalyzed Hydroformylation and Ir‐Catalyzed Allylic Amination

  Zuzana Krausová, Petr Sehnal, Bojan P. Bondzic, Serghei Chercheja, Peter Eilbracht, Irena G. Stará, David Šaman, Ivo Starý
  Annalen der Chemie und Pharmacie 05/2011; 2011(20‐21):3849 - 3857. · 3.10 Impact Factor
• Source

  Available from: uni-mainz.de

  Article: Racemic and Optically Pure Heptahelicene‐2‐carboxylic Acid: Its Synthesis and Self‐Assembly into Nanowire‐Like Aggregates

  Jiří Rybáček, Gloria Huerta-Angeles, Adrian Kollárovič, Irena G. Stará, Ivo Starý, Philipp Rahe, Markus Nimmrich, Angelika Kühnle
  Annalen der Chemie und Pharmacie 12/2010; 2011(5):853 - 860. · 3.10 Impact Factor
• Article: [11]Anthrahelicene on InSb(001) c(8×2): a low-temperature scanning probe microscopy study.

  Jakub S Prauzner-Bechcicki, Szymon Godlewski, Janusz Budzioch, Grzegorz Goryl, Lukasz Walczak, Petr Sehnal, Irena G Stará, Ivo Starý, Francisco Ample, Christian Joachim, Marek Szymonski
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  ABSTRACT: The adsorption of individual [11]anthrahelicene molecules and their self-assembly into monolayer islands on an InSb(001) c(8×2) reconstructed surface is studied with low-temperature scanning probe microscopy. A racemic mixture is deposited on atomically flat terraces of InSb at room temperature. At lower coverage, the molecules tend to decorate atomic step edges of the substrate. At higher coverage, [11]anthrahelicene molecules form 2D islands. A quasi-hexagonal ordering of molecules within the layer is identified. Furthermore, it is shown that molecules adsorb with the helical axis almost perpendicular to the substrate. Interference between tunneling through the molecular layer and directly through space is reported. Finally, experimental results are compared to those of theoretical calculations.
  ChemPhysChem 11/2010; 11(16):3522-8. · 3.41 Impact Factor
• Article: A versatile synthesis of functionalized pentahelicenes.

  Olivier Songis, Jirí Mísek, Markus B Schmid, Adrian Kollárovic, Irena G Stará, David Saman, Ivana Císarová, Ivo Starý
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  ABSTRACT: A general synthetic methodology for the preparation of functionalized (hetero)helicenes has been developed. It employs the sequence of a double propargyl organometallics (Li, Mg, Ga/In) addition to a tolan-2,2'-dialdehyde-type intermediate, a cobalt-catalyzed/cobalt-mediated [2 + 2 + 2] cycloisomerization of a triyne intermediate, and a double silica gel-assisted acetic acid elimination to receive pentahelicene, 1,14-diazapentahelicene, and 3,12-dichloro-, 3,12-dichloro-7-trimethylsilyl-, and 3,12-di-tert-butylpentahelicene. 3,12-Dichloropentahelicene undergoes a Suzuki-Miyaura coupling with aryl boronic acids (or ester) under palladium catalysis to afford 3,12-diarylpentahelicenes.
  The Journal of Organic Chemistry 10/2010; 75(20):6889-99. · 4.45 Impact Factor
• Article: Determination of acid-base dissociation constants of azahelicenes by capillary zone electrophoresis.

  Sille Ehala, Jirí Mísek, Irena G Stará, Ivo Starý, Václav Kasicka
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  ABSTRACT: CZE was employed to determine acid-base dissociation constants (pK(a)) of ionogenic groups of azahelicenes in methanol (MeOH). Azahelicenes are unique 3-D aromatic systems, which consist of ortho-fused benzene/pyridine units and exhibit helical chirality. The pK(a) values of pyridinium groups of the studied azahelicenes were determined from the dependence of their effective electrophoretic mobility on pH by a nonlinear regression analysis. The effective mobilities of azahelicenes were determined by CZE at pH range between 2.1 and 10.5. Thermodynamic pK(a) values of monobasic 1-aza[6]helicene and 2-aza[6]helicene in MeOH were determined to be 4.94 +/- 0.05 and 5.68 +/- 0.05, respectively, and pK(a) values of dibasic 1,14-diaza[5]helicene were found to be equal to 7.56 +/- 0.38 and 8.85 +/- 0.26. From these values, the aqueous pK(a) of these compounds was estimated.
  Journal of Separation Science 09/2008; 31(14):2686-93. · 2.73 Impact Factor
• Article: Evaluation of the intramolecular basis set superposition error in the calculations of larger molecules: [n]helicenes and Phe-Gly-Phe tripeptide.

  Haydée Valdés, Vojtech Klusák, Michal Pitonák, Otto Exner, Ivo Starý, Pavel Hobza, Lubomír Rulísek
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  ABSTRACT: Correlated ab initio calculations on large systems, such as the popular MP2 (or RI-MP2) method, suffer from the intramolecular basis set superposition error (BSSE). This error is typically manifested in molecules with folded structures, characterized by intramolecular dispersion interactions. It can dramatically affect the energy differences between various conformers as well as intramolecular stabilities, and it can even impair the accuracy of the predictions of the equilibrium molecular structures. In this study, we will present two extreme cases of intramolecular BSSE, the internal stability of [n]helicene molecules and the relative energies of various conformers of phenylalanyl-glycyl-phenylalanine tripeptide (Phe-Gly-Phe), and compare the calculated data with benchmark values (experimental or high-level theoretical data). As a practical and cheap solution to the accurate treatment of the systems with large anticipated value of intramolecular BSSE, the recently developed density functional method augmented with an empirical dispersion term (DFT-D) is proposed and shown to provide very good results in both of the above described representative cases.
  Journal of Computational Chemistry 05/2008; 29(6):861-70. · 4.58 Impact Factor
• Source

  Available from: isivast.org.vn

  Article: On the origin of diastereoselectivity in [2 + 2 + 2] cycloisomerization of chiral triynes: controlling helicity of helicene-like compounds by thermodynamic factors.

  Petr Sehnal, Zuzana Krausova, Filip Teplý, Irena G Stara, Ivo Starý, Lubomír Rulísek, David Saman, Ivana Císarova
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  ABSTRACT: Diastereoselective CoI-mediated [2 + 2 + 2] cycloisomerization of CH(3)O-substituted optically pure aromatic triynes to obtain nonracemic functionalized helicene-like compounds (comprising a penta-, hexa-, and heptacyclic helical scaffold) was studied. The stereochemical outcome of the reaction at 140 degrees C using CpCo(CO)(2) was controlled by thermodynamic factors yielding diastereomeric ratios up to 91:9. Using CpCo(ethylene)(2) at room temperature, a kinetic control took place leading to the loss of stereoselectivity. Barriers to epimerization for selected helicene-like compounds were measured indicating their lower configurational stability in comparison to the parent carbohelicenes. Free energy differences between corresponding pairs of diastereomers (calculated at the DFT B3LYP/TZV+P level) were in excellent agreement with the experimental data and allowed for the prediction of the stereochemical outcome of the reaction. An optically pure hexacyclic helicene-like alcohol was prepared on a multigram scale. Its X-ray structure confirmed the previous helicity assignments being based on (1)H-(1)H correlations in ROESY (1)H NMR spectra.
  The Journal of Organic Chemistry 04/2008; 73(6):2074-82. · 4.45 Impact Factor
• Article: A straightforward route to helically chiral N-heteroaromatic compounds: practical synthesis of racemic 1,14-diaza[5]helicene and optically pure 1- and 2-aza[6]helicenes.

  Jirí Mísek, Filip Teplý, Irena G Stará, Milos Tichý, David Saman, Ivana Císarová, Pavel Vojtísek, Ivo Starý
  Angewandte Chemie International Edition 02/2008; 47(17):3188-91. · 13.45 Impact Factor
• Article: Evaluation of the intramolecular basis set superposition error in the calculations of larger molecules: [

  Haydée Valdés, Vojtech Klusák, Michal Pitonák, Otto Exner, Ivo Starý, Pavel Hobza, Lubomír Rulísek
  Journal of Computational Chemistry. 01/2008; 29:861-870.
• Article: Chiral superbases: the proton affinities of 1‐ and 2‐aza[6]helicene in the gas phase

  Jana Roithová, Detlef Schröder, Jiří Míšek, Irena G. Stará, Ivo Starý
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  ABSTRACT: The proton affinities (PAs) of 1- and 2-azahelicene were determined using various mass spectrometric techniques and complementary results from density functional theory. With PAs of about 1000 kJ mol−1, the helical backbone of both compounds offer promising perspectives for future research on enantioselective reactions of these helical nitrogen bases. Copyright © 2007 John Wiley & Sons, Ltd.
  Biological Mass Spectrometry 08/2007; 42(9):1233 - 1237. · 3.41 Impact Factor
• Article: A Convenient Route to 2‐Hydroxy‐ and 2,15‐Dihydroxyhexahelicene

  Filip Teplý, Irena G. Stará, Ivo Starý, Adrian Kollárovič, Daniel Luštinec, Zuzana Krausová, David Šaman, Pavel Fiedler
  Annalen der Chemie und Pharmacie 07/2007; 2007(25):4244 - 4250. · 3.10 Impact Factor
• Article: Asymmetric synthesis of [7]helicene-like molecules.

  Irena G Stará, Zuzana Alexandrová, Filip Teplý, Petr Sehnal, Ivo Starý, David Saman, Milos Budesínský, Josef Cvacka
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  ABSTRACT: [reaction: see text] A new approach to nonracemic [7]helicene-like molecules has been developed. Stereoselective Co(I)-mediated [2 + 2 + 2] cycloisomerization of aromatic triynes containing an asymmetric carbon atom produces [7]helicene-like scaffolds in diastereomeric ratios up to 100:0. This central-to-helical chirality transfer can be controlled by the absolute configuration at the asymmetric center and by the presence of carbon substituents.
  Organic Letters 07/2005; 7(13):2547-50. · 5.86 Impact Factor
• Article: Synthesis of 3-hexahelicenol and its transformation to 3-hexahelicenylamines, diphenylphosphine, methyl carboxylate, and dimethylthiocarbamate.

  Filip Teplý, Irena G Stará, Ivo Starý, Adrian Kollárovic, David Saman, Stepán Vyskocil, Pavel Fiedler
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  ABSTRACT: A nonphotochemical synthetic route to 3-hexahelicenol is reported. It involves a key [2+2+2] cycloisomerization of CH(3)O-substituted triyne that is readily available from 1-methoxy-3-methylbenzene and 1-bromo-2-(bromomethyl)naphthalene. Further functional group transformations led to 3-CO(2)CH(3), 3-NH(2), 3-PPh(2), and 3-SC(O)N(CH(3))(2) substituted hexahelicenes.
  The Journal of Organic Chemistry 07/2003; 68(13):5193-7. · 4.45 Impact Factor
• Article: Synthesis of [5]-, [6]-, and [7]helicene via Ni(0)- or Co(I)-catalyzed isomerization of aromatic cis,cis-dienetriynes.

  Filip Teplý, Irena G Stará, Ivo Starý, Adrian Kollárovic, David Saman, Lubomír Rulísek, Pavel Fiedler
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  ABSTRACT: An original approach to helicene frameworks exploiting atom economic isomerization of appropriate energy-rich aromatic cis,cis-dienetriynes has been developed. The new paradigm provides nonphotochemical syntheses of helicenes based on the easy, convergent, and modular assembly of key cis,cis-dienetriynes and their nickel(0)-catalyzed [2+2+2] cycloisomerization. The potential of the methodology is underlined by the syntheses of the parent [5]helicene (2), 7,8-dibutyl[5]helicene (23), [6]helicene (24), and [7]helicene (25). The approach can be adapted to prepare functionalized helicenes as exemplified by the eight-step synthesis of 7,8-dibutyl-2,3-dimethoxy[6]helicene (34). Density functional theory (DFT) calculations showed that bis[2-((1Z)-1-buten-3-ynyl)phenyl]acetylene (1) and isomeric [5]helicene (2) differ enormously in the Gibbs energy content (DeltaG = -136.6 kcal x mol(-1)) to favor highly the devised intramolecular simultaneous construction of three aromatic rings.
  Journal of the American Chemical Society 09/2002; 124(31):9175-80. · 9.91 Impact Factor
• Article: A Novel Strategy for the Synthesis of Molecules with Helical Chirality. Intramolecular [2 + 2 + 2] Cycloisomerization of Triynes under Cobalt Catalysis†

  Irena G. Stará, Ivo Starý, Adrian Kollárovič, Filip Teplý, David Šaman, Miloš Tichý
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  ABSTRACT: A straightforward synthetic approach to a new class of molecules with helical chirality has been developed involving an intramolecular [2 + 2 + 2] cycloisomerization of triynes under CpCo(CO)2/PPh3 catalysis. The cyclization reaction is promoted by visible light irradiation. Starting from 1,2-diarylacetylenes with two terminal or methyl-substituted tethered acetylene moieties (1a,b, 4, 5, and 7), the target products (8a,b, 11, 12, and 14) are obtained in 64−89% yield. The triynes bearing terminal trimethylsilyl groups (1c, 2, and 3) are less reactive and afford the products (8c, 9a,b, and 10) in 23−71% yield. The ability of the trimethylsilylated derivatives to cycloisomerize strongly depends on the tether length. The cyclized products (8−14) with five, six, and seven ortho-fused rings structurally resemble classical helicenes. Several representatives (8b, 11, 12, and 14) have been resolved into enantiomers by HPLC on a chiral column. Thus, the methodology exhibits a considerable versatility and allows the preparation of a variety of helical objects.
  05/1998;
• Article: Transition metal catalysed synthesis of tetrahydro derivatives of [5]-, [6]- and [7]helicene

  Irena G Stará, Ivo Starý, Adrian Kollárovič, Filip Teplý, Štěpán Vyskočil, David Šaman
  Tetrahedron Letters 40(10):1993-1996. · 2.68 Impact Factor
• Article: Modified Synthesis of Heptahelicene and Its Resolution Into Single Enantiomers

  Zuzana Alexandrová, Petr Sehnal, Irena G. Stará, Ivo Starý, David Šaman, Stephen G Urquhart, Edwige Otero
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  ABSTRACT: A practical synthesis of racemic heptahelicene has been develeped being based on key [2+2+2] cycloisomerization of bis[2-(but-3-yn-1-yl)-1-naphthyl]acetylene under CpCo(CO)₂/PPh₃ or CpCo(C₂H₄)₂ catalysis. The application of the Ni(cod)₂ catalyst with (-)-( S _a)-(2'-methoxy-1,1'-binaphthalen-2-yl)diphenylphosphane resulted in enantioselective triyne cyclization to provide (+)-7,8,11,12-tetrahydroheptahelicene in 40% ee. Optically pure (-)-( M )- and optically highly enriched (+)-( P )-heptahelicene were obtained on a milligram scale by resolution of racemate by chiral HPLC on a semipreparative Whelk-O1 column.
• Article: Axially Chiral Selectors of C2 Symmetry Bound to Silica: Synthesis and HPLC-Evaluation

  Miloš Tichý, Jana Holanová, Ivo Starý, Irena G. Stará, Jiří Závada
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  ABSTRACT: Axially chiral biaryl stationary phases (CSPs) of C ₂ symmetry bound to 3-aminopropyl silica both by ionic and covalent bond were prepared. The separation effectivity of the CSPs so obtained was investigated using 2-acylamino alcohols and biaryl derivatives as analytes. Whereas ionically bound phases derived from biphenyl-2,2'-dicarboxylic or 2,2'-bipyridine-3,3'-dicarboxylic acids (CSP 1, 2, 3 and 4) generally exhibited good resolving performance for 2-acylamino alcohols, they were ineffective for biaryl derivatives. On the other hand, covalent CSPs showed poor selector properties with acylamino alcohols; the binaphthyl CSP 7 resolved some of the biaryl analytes. Phase CSP 6 was completely inactive toward all the compounds tested. Absolute configuration of 4,4',6,6'-tetranitrobiphenyl-2,2'-dicarboxylic acid ( II ) has been derived from its CD spectrum and some speculations on configuration of bipyridine diacid IV are presented.