Publication detail

Synthesis, structure, spectral properties and DFT quantum chemical calculations of 4-aminoazobenzene dyes. Effect of intramolecular hydrogen bonding on photoisomerizati

GEORGIEV, A. BUBEV, E. DIMOV, D. YANCHEVA, D. ZHIVKOV, I. KRAJČOVIČ, J. VALA, M. WEITER, M. MACHKOVA, M.

Original Title

Type

journal article in Web of Science

Language

English

Original Abstract

In this paper three different “push-pull” 4-aminoazobenzene dyes have been synthesized in order to characterize their photochromic behavior in different solvents. The molecular geometry was optimized by DFT/B3LYP functional combined with the standard 6–31 + G(d,p) basis set for trans (E) and cis (Z) isomers and the energy levels of HOMO and LUMO frontier orbitals were computed using IEFPCM solvation in CHCl3 and DMF. The calculated results were compared to the experimental optical band gap and HOMO values of cyclic voltammetry. The intramolecular six-membered hydrogen bond was formed in both isomers of the synthesized dyes. The thermodynamic parameters such as total electronic energy E (RB3LYP), enthalpy H298 (sum of electronic and thermal enthalpies), free Gibbs energy G298 (sum of electronic and thermal free Gibbs energies) and dipole moment μ were computed for trans (E) and cis (Z) isomers in order to estimate the ΔEtrans → cis, Δμtrans → cis, ΔHtrans → cis, ΔGtrans → cis and ΔStrans → cis values. The NBO analysis was performed in order to understand the intramolecular charge transfer and energy of resonance stabilization. The solvatochromic shift was evaluated by UV-VIS spectroscopy in CHCl3 (nonpolar), EtOH (polar protic) and DMF (polar aprotic) solvents to determine the electron withdrawing and donating properties of the substituents on electron transitions energy. Through the increasing solvent polarity a strong bathochromic shift is observed. The photoisomerization experiments have been performed in two solvents CHCl3 (nonpolar) and DMF (polar aprotic) by UV light irradiation with λ = 365 nm at equal concentrations and time of illuminations. The electronic spectra were computed by TD-DFT after geometry optimization using IEFPCM solvation in CHCl3 and DMF. The degree of photoisomerization was calculated for the three azo chromophores in both solvents. By using first derivative of the UV-VIS spectra it was possible to resolve the overlapped electron transitions absorption bands. The existing intramolecular hydrogen bond in the azo chromophores was discussed in relation to the isomerization mechanisms and relative stability of the cis (Z) isomers.

Keywords

4-aminoazobenzene dyes DFT quantum chemical calculations HOMO and LUMO energy levels Solvatochromism Photoisomerization UV-VIS spectroscopy

Authors

GEORGIEV, A.; BUBEV, E.; DIMOV, D.; YANCHEVA, D.; ZHIVKOV, I.; KRAJČOVIČ, J.; VALA, M.; WEITER, M.; MACHKOVA, M.

Released

15. 3. 2017

Publisher

Elsevier B.V.

Location

Amsterdam, The Netherlands

ISBN

1386-1425

Periodical

SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY

Number

175

State

United Kingdom of Great Britain and Northern Ireland

Pages from

Pages to

Pages count

URL

http://www.sciencedirect.com/science/article/pii/S1386142516307211

BibTex

@article{BUT131303,
  author="GEORGIEV, A. and BUBEV, E. and DIMOV, D. and YANCHEVA, D. and ZHIVKOV, I. and KRAJČOVIČ, J. and VALA, M. and WEITER, M. and MACHKOVA, M.",
  title="Synthesis, structure, spectral properties and DFT quantum chemical calculations of 4-aminoazobenzene dyes. Effect of intramolecular hydrogen bonding on photoisomerizati",
  journal="SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY",
  year="2017",
  number="175",
  pages="76--91",
  doi="10.1016/j.saa.2016.12.005",
  issn="1386-1425",
  url="http://www.sciencedirect.com/science/article/pii/S1386142516307211"
}