@article{KammKammSchmidtetal.2006,
  author    = {Kamm, Birgit and Kamm, Michael and Schmidt, Matthias and Starke, Ines and Kleinpeter, Erich},
  title     = {Chemical and biochemical generation of carbohydrates from lignocellulose-feedstock (Lupinus nootkatensis) : quantification of glucose},
  issn      = {0045-6535},
  doi       = {10.1016/j.chemosphere.2005.03.073},
  year      = {2006},
  abstract  = {Different chemical and enzymatic methods were applied for the hydrolysis of main stems from Lupinus nootkatensis (harvest November 2002). The whole process (all steps) is based on the lignocellulose-feedstock biorefinery regime. The acid hydrolysis of L. was performed with concentrated hydrochloric acid; advantages in this process are exothermic hydrolysis and the possibility of acid recovery. Enzymatic hydrolysis achieved high yields of fermentable carbohydrates (regarding to input cellulose) with high selectivity. However, this way requires the generation of cellulose from L. by chemical pulping. Monosaccharide derivatives thus obtained were identified by their GC retention times and the corresponding MS fragmentation. Hexamethyldisilazane was used as derivatization reagent to prepare the trimethylsilyl derivatives of the carbohydrates and of the degradations products of cellulose from the different fractions. The glucose content was quantified by GC peak integration with respect to an internal standard.},
  language  = {en}
}
@article{RasovicSteelKleinpeteretal.2007,
  author    = {Rasovic, Aleksandar and Steel, Peter J. and Kleinpeter, Erich and Markovic, Rade},
  title     = {Regioselective synthesis of 1,3-thiazines by sequential 4-oxothiazolidine to 1,2-dithiole to 1,3-thiazine transformations : role of intramolecular non-bonded S...O interactions},
  doi       = {10.1016/j.tet.2006.12.075},
  year      = {2007},
  abstract  = {A new synthetic approach to 2,3-dihydro-4H-1,3-thiazine derivatives based upon reductive rearrangement of 1,2- dithiole-3-ylidene thiones has been developed. In turn, the 1,2-dithiole derivatives were prepared by an efficient ring- opening-closing process of 2-alkylidene-4-oxothiazolidines, induced in the presence of Lawesson's reagent by intramolecular non-bonded 1,5-type S...O interactions in the 4-oxothiazolidine precursors.},
  language  = {en}
}
@article{KleinpeterRollaKochetal.2006,
  author    = {Kleinpeter, Erich and Rolla, Nadja and Koch, Andreas and Taddei, Fernando},
  title     = {Hyperconjugation and the increasing bulk of OCOCX3 substituents in trans-1,4-disubstituted cyclohexanes destabilize the diequatorial conformer},
  issn      = {4393-4399},
  doi       = {10.1021/Jo0600858},
  year      = {2006},
  abstract  = {The trans diesters of 1,4-cyclohexanediol with a number of acetic acid analogues, CX3COOH, of varying steric hindrance and polarity (CX3 = Me, Et, iso-Pr, tert-Bu, CF3, CH2Cl, CHCl2, CCl3, CH2Br, CHBr2, CBr3) were synthesized, and the axial, axial/equatorial, equatorial conformational equilibria were studied by low-temperature H-1 NMR spectroscopy in CD2Cl2. The structures and relative energies of the axial, axial and equatorial, equatorial conformers were calculated at both the MP2/6-311G* and the MP2/6-311+G* levels of theory, and it was only by including diffuse functions that a good correlation of Delta G degrees(calcd) vs Delta G(exptl) could be obtained. Both the structures and the energy differences of the axial, axial and equatorial, equatorial conformers are discussed with respect to the established models of conformational analysis, viz., steric 1,3-diaxial and hyperconjugative interactions. Interestingly, the hyperconjugative interactions sigma(C-C)/sigma(C-H)->sigma*(C-O), together with a steric effect which also destabilizes the equatorial, equatorial conformers on increasing bulk of the substituents, proved to dominate the position of the conformational equilibria. In addition, the preference of the axial, axial conformers with respect to their equatorial, equatorial analogues was greater than expected from the conformational energies of the corresponding substituents in the monosubstituted cyclohexyl esters. The reason for this very interesting and unexpected result is also discussed},
  language  = {en}
}
@article{YonedaLealSeidletal.2007,
  author    = {Yoneda, Julliane Diniz and Leal, Katia Zaccur and Seidl, Peter Rudolf and Azeredo, Rodrigo Bagueira de V. and Kleinpeter, Erich},
  title     = {Camphor : a good model for illustrating NMR techniques},
  year      = {2007},
  abstract  = {CAMPHOR: A GOOD MODEL FOR ILLUSTRATING NMR TECHNIQUES. The use of Nuclear Magnetic Resonance spectroscopy to establish the three-dimensional structures of molecules is an important component of modern Chemistry courses. The combination of techniques that can be used for this purpose is conveniently illustrated by their application to the camphor molecule. This paper presents applications of several techniques used in NMR spectral interpretation in an increasing order of complexity. The result of individual experiments is illustrated in order to familiarize the user with the way connectivity through bonds and through space is established from 1D/2D-NMR spectra and molecular stereochemistry is determined from different NMR experiments},
  language  = {en}
}
@article{ModarresiAlamKhamooshiRostamizadehetal.2007,
  author    = {Modarresi-Alam, Ali Reza and Khamooshi, Ferydoon and Rostamizadeh, Mohsen and Keykha, Hossein and Nasrollahzahdeh, Mahmoud and Bijanzadeh, Hamid-Reza and Kleinpeter, Erich},
  title     = {Dynamic 1H NMR spectroscopic study of the restricted S-N rotation in aryl-N-(arylsulfonyl)-N- (triphenylphosphoranylidene)imidocarbamates},
  year      = {2007},
  abstract  = {Dynamic 1H NMR (500 MHz) investigation of aryl-N-(arylsulfonyl)-N-(triphenylphosphoranylidene)imidocarbamates in CDCl3, CD3COCD3, and CD3OD at the temperature range of 183-298 K is reported. The observed free energy barriers (almost 12 kcal mol;1) are attributed to conformational isomerization about the N{\`u}S bond and these barriers show very little solvent dependence.},
  language  = {en}
}
@article{ModarresiNajafiRostamizadehetal.2007,
  author    = {Modarresi, Ali Reza and Najafi, Parisa and Rostamizadeh, Mohsen and Keykha, Hossein and Bijanzadeh, Hamid-Reza and Kleinpeter, Erich},
  title     = {Dynamic 1H NMR study of the barrier to rotation about the C-N bond in primary carbamates and its solvent dependence},
  year      = {2007},
  abstract  = {The dynamic 1H NMR study of some primary carbamates in the solvents CDCl3 and CD3COCD3 between 183 and 298 K is reported. The free energies of activation, thus obtained (12.4 to 14.3 kcal mol-1), were attributed to the conformational isomerization about the N-C bond. These barriers to rotation show solvent dependence in contrast to the tertiary analogues and are lower in free energy by ca. 2-3 kcal mol-1.},
  language  = {en}
}
@article{KleinpeterStamboliyska2008,
  author    = {Kleinpeter, Erich and Stamboliyska, Bistra A.},
  title     = {Quantification of the Push-Pull Character of Donor-Acceptor Triazenes},
  doi       = {10.1021/Jo8013758},
  year      = {2008},
  abstract  = {The Push-pull character of two series of donor-acceptor triazenes has been quantified by C-13 and N-15 chemical shift differences of the partial N(1)=N(2) and N(3)=C(4) double bonds in the central linking C=N-N=N-C unit and by the quotient of the occupations of both the bonding pi and antibonding orbitals pi* of these partial double bonds. Excellent correlations of the two estimates, to quantify the push-pull effect, with the bond lengths strongly recommend the occupation quotients pi*/pi, the N-15 chemical shift differences Delta delta[N(l),N(2)], and the corresponding bond lengths as reasonable sensors for quantifying charge alternation along the C=N-N=N-C linking unit, for the donor- acceptor quality of the triazenes 1 and 2 and for the molecular hyperpolarizability beta(0) of these compounds. Within this context, certain Substances can be strongly recommended for NLO application.},
  language  = {en}
}
@article{KlikaKramerKleinpeter2009,
  author    = {Klika, Karel D. and Kramer, Markus and Kleinpeter, Erich},
  title     = {DFT computational studies of hydrogen bonding-based diastereomeric complexes : limitations and applications to enantiodifferentiation},
  issn      = {0166-1280},
  doi       = {10.1016/j.theochem.2009.08.003},
  year      = {2009},
  abstract  = {Molecular modeling calculations using DFT at the B3LYP/6-31G(d,p) level of theory have been performed on diastereomeric complexes formed between chiral carboxylate anions and chiral urea receptors, a combination previously demonstrated to enable enantiodifferentiation by electrochemical sensing. The calculations correctly predicted the stability order of the enantiomers in acetonitrile solution when the distinction between the enantiomers was above the declared threshold reliability value of 1 kcal mol;1 for computations at this level of theory. Thus, the calculations can not only be applied to predict the likely success of undertakings using the analytical method, it can also, provided ;E is sufficient, potentially be used to determine the absolute configuration of chiral analytes with at least the racemate in hand. The previously successful enantiodifferentiations of various amino acids and alcohols using chiral ion mobility spectroscopy (CIMS) with (S)-2-butanol as the chiral selector were also evaluated by DFT calculations. The calculations again correctly predicted the stability order of the enantiomers when the calculated ;E was above the threshold value though cases not providing a value for ;E above the threshold value was problematic for this system. Attempts to address this shortcoming included an expanded conformational evaluation, a broader analytical approach, and an extended basis set.},
  language  = {en}
}
@article{ShainyanUshakovMeshcheryakovetal.2008,
  author    = {Shainyan, Bagrat A. and Ushakov, Igor A. and Meshcheryakov, Vladimir I. and Koch, Andreas and Kleinpeter, Erich},
  title     = {Variable temperature NMR and theoretical study of the stereodynamics of 5-trifluoromethylsulfonyl-1,3,5- dioxaazinane : Perlin effect subject to heteroatom substitution},
  year      = {2008},
  abstract  = {Multinuclear dynamic NMR spectroscopy of 5-trifluoromethylsulfonyl-1,3,5-dioxaazinane (4) revealed the existence of two close in energy chair conformers with differently oriented CF3 groups with respect to the ring. Of the two alternative routes for their interconversion, the ring inversion path with intermediate formation of the corresponding 2,5-twist-conformer is preferred, with the energy barrier of 11.2 kcal/mol in excellent agreement with the experimental value (11.7 kcal/mol). The Perlin effect is studied experimentally and calculated theoretically for all CH2 groups and found to be subject to the nature of the adjacent heteroatoms O and N, respectively.},
  language  = {en}
}
@article{KleinpeterKochShainyan2008,
  author    = {Kleinpeter, Erich and Koch, Andreas and Shainyan, Bagrat A.},
  title     = {Cyclobutadiene dianion derivatives : Planar 4c,6e or three-dimensional 6c,6e aromaticity?},
  doi       = {10.1016/j.theochem.2008.05.027},
  year      = {2008},
  abstract  = {The spatial magnetic properties (Through Space NMR Shieldings - TSNMRS) of two cyclobutadiene derivatives (2 and 5) and of a number of cyclobutadiene dianion derivatives (3, 4 and 6-8) have been calculated by the GIAO perturbation method employing the Nucleus-Independent Chemical Shift (NICS) concept of P. v. Ragu{\´e} Schleyer, and visualized as Iso-Chemical-Shielding Surfaces (ICSS) of various size and direction. TSNMRS values can be successfully employed to quantify and visualize the (anti)aromaticity of the compounds studied and to discuss the influence of Li+ complexation to cyclobutadiene dianion (4a, 7 and 8) on planar 4c,6e or three-dimensional 6c,6e aromaticity.},
  language  = {en}
}