@article{BalciKochKleinpeter2009,
  author    = {Balci, Kubilay and Koch, Andreas and Kleinpeter, Erich},
  title     = {A theoretical IR spectroscopic study based on DFT calculations for free mn-15S(2)O(3) maleonitrile-dithiacrown ether compound},
  issn      = {0022-2860},
  doi       = {10.1016/j.molstruc.2008.08.027},
  year      = {2009},
  abstract  = {The theoretically possible stable conformers of free mn-15S2O3 maleonitrile-dithiacrown ether molecule were searched by means of a conformational study which consists of molecular dynamics and energy minimization calculations performed with MM2 force field and successive geometry optimization + frequency calculations performed first at B3LYP/3- 21G and then at B3LYP/6-31G(d) levels of theory. The obtained calculation results have clearly indicated that the free molecule in electronic ground state is very flexible and accordingly has many possible stable conformers of different conformational properties at room temperature; among them, the one having a macrocyclic ring structure in which all of the ether units oriented toward the center of the ring was determined the energetically most preferable conformer. In addition, the equilibrium geometrical parameters, vibrational normal modes and associated IR spectral data of the determined most stable three conformers of the molecule were calculated at B3LYP/6-31+G(d) and B3LYP/6-31++G(d,p) levels of theory. A successful assignment of the fundamental bands observed in the recorded experimental solid phase and solution phase IR spectra of the molecule was achieved in the light of the theoretical data obtained from these DFT calculations. To fit the calculated harmonic wavenumbers to the experimental ones, two different scaling procedures, referred to as "Scaled Quantum Mechanical Force Field (SQM FF) methodology" and "Scaling wavenumbers with empirical dual scale factors", were proceeded independently.},
  language  = {en}
}
@article{BalciKochKleinpeter2006,
  author    = {Balci, Kubilay and Koch, Andreas and Kleinpeter, Erich},
  title     = {A comparative vibrational spectroscopic investigation of free mn-12S(2)O(2) and fn-12S(2)O(2) dithiacrown ethers based on DFT calculations},
  issn      = {0022-2860},
  doi       = {10.1016/j.molstruc.2005.10.048},
  year      = {2006},
  abstract  = {A successful assignment for the fundamental bands observed in the experimental IR spectra of mn-12S(2)O(2) and fn-12S(2)O(2) dithiacrown ethers was achieved by the aid of the density functional theory (DFT) based quantum mechanical calculations carried out at the 133LYP/6-31G(d) and B3LYP/6-31 + G(d) level of theory. Two different scaling approaches, '(i) scaled quantum mechanics force field (SQM FF) methodology', and (ii) the 'scaling frequencies with dual empirical scale factors', were used in order to fit the calculated harmonic frequencies to the experimental ones. Potential energy distribution (PED) calculations were carried out to define the internal coordinate contributions to each normal mode and to define the corresponding normal modes of the molecules. The effects of the conformational differences onto the IR active normal modes of the two isomeric molecules and their corresponding experimental frequencies were discussed in the light of the calculated spectral data.},
  language  = {en}
}
@article{BalciYaparAkkayaetal.2012,
  author    = {Balci, Kubilay and Yapar, G. and Akkaya, Y. and Akyuz, S. and Koch, Andreas and Kleinpeter, Erich},
  title     = {A conformational analysis and vibrational spectroscopic investigation on 1,2-bis(o-carboxyphenoxy) ethane molecule},
  series = {Vibrational spectroscopy : an international journal devoted to applications of infrared and raman spectroscopy},
  volume    = {58},
  journal   = {Vibrational spectroscopy : an international journal devoted to applications of infrared and raman spectroscopy},
  number    = {1-2},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0924-2031},
  doi       = {10.1016/j.vibspec.2011.11.011},
  pages     = {27 -- 43},
  year      = {2012},
  abstract  = {The minima on the potential energy surface of 1,2-bis(o-carboxyphenoxy)ethane (CPE) molecule in its electronic ground state were searched by a molecular dynamics simulation performed with MM2 force field. For each of the found minimum-energy conformers, the corresponding equilibrium geometry, charge distribution, HOMO-LUMO energy gap, force field, vibrational normal modes and associated IR and Raman spectral data were determined by means of the density functional theory (DFT) based electronic structure calculations carried out by using B3LYP method and various Pople-style basis sets. The obtained theoretical data confirmed the significant effects of the intra- and inter-molecular hydrogen bonding interactions on the conformational structure, force field, and group vibrations of the molecule. The same data have also revealed that two of the determined stable conformers, both of which exhibit pseudo-crown structure, are considerably more favorable in energy to the others and accordingly provide the major contribution to the experimental spectra of CPE. In the light of the improved vibrational spectral data obtained within the "SQM FF" methodology and "Dual Scale Factors" approach for the monomer and dimer forms of these two conformers, a reliable assignment of the fundamental bands observed in the experimental room-temperature IR and Raman spectra of the molecule was given, and the sensitivities of its group vibrations to conformation, substitution and dimerization were discussed.},
  language  = {en}
}
@article{KleinpeterBalciYaparetal.2012,
  author    = {Kleinpeter, Erich and Balci, Kubilay and Yapar, G. and Akkaya, S. and Akyuz, S. and Koch, Andreas},
  title     = {A conformational analysis and vibrational spectroscopic investigation on 1,2-bis(o-carboxyphenoxy) ethane molecule},
  year      = {2012},
  abstract  = {The minima on the potential energy surface of 1,2-bis(o-carboxyphenoxy) ethane (CPE) molecule in its electronic ground state were searched by a molecular dynamics simulation performed with MM2 force field. For each of the found minimum-energy conformers, the corresponding equilibrium geometry, charge distribution, HOMO-LUMO energy gap, force field, vibrational normal modes and associated IR and Raman spectral data were determined by means of the density functional theory (DFT) based electronic structure calculations carried out by using B3LYP method and various Pople- style basis sets. The obtained theoretical data confirmed the significant effects of the intra- and inter-molecular hydrogen bonding interactions on the conformational structure, force field, and group vibrations of the molecule. The same data have also revealed that two of the determined stable conformers, both of which exhibit pseudo-crown structure, are considerably more favorable in energy to the others and accordingly provide the major c ntribution to the experimental spectra of CPE. In the light of the improved vibrational spectral data obtained within the "SQM FF" methodology and "Dual Scale Factors" approach for the monomer and dimer forms of these two conformers, a reliable assignment of the fundamental bands observed in the experimental room-temperature IR and Raman spectra of the molecule was given, and the sensitivities of its group vibratb20s to conformation, substitution and dimerization were discussed.},
  language  = {en}
}