African Journal of
Pure and Applied Chemistry

  • Abbreviation: Afr. J. Pure Appl. Chem.
  • Language: English
  • ISSN: 1996-0840
  • DOI: 10.5897/AJPAC
  • Start Year: 2007
  • Published Articles: 354

Full Length Research Paper

Complexes of Nile Red and b- or g-cyclodextrin: A semiempirical-density functional theory-molecular dynamics route

Ruth Hojvat1,2, Dora A. Barbiric3 and Eduardo A. Castro4*
1Facultad de Ciencias Exactas y Naturales, Universidad de Belgrano, Zabala 1837 CABA (CP 1426DQG) Argentina. 2Escuela de Tecnología y Escuela de Ciencias Agrarias, Universidad Nacional del Noroeste de la Provincia de Buenos Aires, Sede Junin, R. Sáenz Peña 456, Junín B6000, Pcia de Buenos Aires, Argentina. 3Facultad de Ingeniería, Universidad de Buenos Aires, Av. Paseo Colón 850, C1063ACV, Buenos Aires, Argentina. 4Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Universidad Nacional de La Plata, Suc. 4, C.C. 16, 1900La Plata, Buenos Aires, Argentina.
Email: [email protected]

  •  Published: 30 November 2011

Abstract

The association of Nile Red (NR) with b-, and g-cyclodextrins (CDs) was analyzed by semiempirical parametric method 3 (PM3), density functional theory-Becke, three-parameter, Lee-Yang-Parr hybrid functional (DFT-B3LYP/6-31G), and molecular dynamics (MD) and Langevin dynamics (LD) calculations, including annealing and molecular mechanics (MM) geometry optimization. Our results suggest that inclusion complexes of NR and both CD are possible but occlusion complexes are more favourable. Differences in the intermolecular H-bonding yielded by the DFT-level of treatment could explain the distinct behaviour regarding deactivation to the ground state of NR in presence of b-, andg-CD in fluorescence experiments. DFT optimization of NR in gaseous state rendered lower twisting angles and larger pyramidalization of the amino group than reported elsewhere.

 

Key words: Molecular modeling, cyclodextrins, Nile Red complexes.