Effets combinés de la substitution d’un ligand hydroxyquinoline (q) par le picolinate (p) et de la double aza-substitution sur les propriétés optoélectroniques de Alq3

  • Fabrice Nahimana
  • Thaddée Barancira
  • Aloys Katihabwa
  • Rachel Akimana
  • Alice Ndayirukiye
  • Godefroid Gahungu Université du Burundi
Keywords: tris- (8-hydroxyquinoline) Aluminium III, double aza-substitution, optoelectronic properties, DFT.

Abstract

With the aim to evaluate the combined effect of the double aza-substitution on the 8-hydroxyquinoline ligand (q) and the
substitution of an 8-hydroxyquinoline ligand by the picolinate (p) on the molecular geometry, electronic structure and optical
properties of tris-(8-hydroxyquinoline) Aluminum III [Alq3], three electronic methods (HF, B3LYP and CIS) coupled to the 6-
31G(d) and 3-21+G(d,p) basis sets were applied on Alq3, Alq2p and two of its double aza-substitution derivatives (in positions
2 & 4 of the 8-hydroxyquinoline ligand to form Al(cx)2p and 5 & 7 to form Al(57n)2p). The optimized geometries of the ground
state (S0) revealed that the molecular shape is conserved by aza-substitution of Alq2p. Calculation of the energies of molecular
orbitals has shown that, compared to Alq3, HOMO and LUMO are stabilized for Alq2p and its two derivatives, the overall
impact of the studied substitutions being an increasing (decreasing) HOMO-LUMO gap (Eg) for the double aza-substitution at
positions 2 and 4 (5 and 7). A comparison of the optimized structures of the S0 and S1 states revealed that the excitation mainly
involves ligand A. The calculated emission spectra show that the substitution of a q ligand of Alq3 by p followed by a double
aza-substitution in positions 2 & 4 (5 & 7) of the other two q ligands would be an efficient approach to modulate the emission
color, a blue (red) shift of about 110 nm (209 nm) being predicted for (Al(cx)2p and Al(57n)2p).

Published
2021-11-30
How to Cite
Nahimana, F., Barancira, T., Katihabwa, A., Akimana, R., Ndayirukiye, A., & Gahungu, G. (2021). Effets combinés de la substitution d’un ligand hydroxyquinoline (q) par le picolinate (p) et de la double aza-substitution sur les propriétés optoélectroniques de Alq3. Journal of University of Burundi, 31(1), 15-23. Retrieved from http://revue.ub.edu.bi/JUB/article/view/180