Page 113 - Book of Abstracts 2020

th
8 Biannual Conference on Chemistry - CHEM 08

New Charge Transfer Complexes of 2,4-

Diaminopyrimidine With Chloranilic Acid and 2,3-
Dichloro-5,6-dicyano-1,4-benzoquinone: Spectroscopic and
Antimicrobial Studies

Wejdan J. Alharby, Maram T. Basha, Reem M. Alghanmi
Chemistry Department, Faculty of Science, University of Jeddah, P.O.
Box 80327, Jeddah 21589, Saudi Arabia.
Email: fmzainy@uj.edu.sa.

ABSTRACT

New charge transfer complexes between the electron donor 2,4-
diaminopyrimidine (DAPY) with π-electron acceptors chloranilic acid (CHA)
and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) have been investigated

spectrophotometrically in methanol. The molecular composition of the CT
complexes was studied, utilizing Job’s and photometric titration methods. The
results confirm the formation of the complexes in 1:1 ratio in methanol. The CT
formation constant (KCT) and the molar extinction coefficient () were calculated
at different temperatures within the range of 293-313 K, using the modified
Benesi-Hildebrand equation. The KCT value for the DAPY-CHA complex was
higher than that of DAPY-DDQ at room temperature.The spectroscopic physical

parameters such as oscillator strength (f), transition dipole moment (µ), charge
transfer energy (ECT), ionization potential (ID) and resonance energy (RN) have
been determined to visualize the nature of interaction between donor and
acceptors. The van’t Hoff equation was applied to calculate some
thermodynamic parameters, including the enthalpy change (ΔH°) and the
entropy change (ΔS°), as well as Gibbs free energy change (ΔG). Furthermore, a
sensitive spectrophotometric method for determining DAPY is proposed and
validated statistically. The solid complex was synthesized and characterized,

1
utilizing elemental analysis, H NMR and FT-IR spectroscopy, and they
confirmed the formation of 1:1 CT complex. The antimicrobial activities of the
considered CT complexes were evaluated against some types of fungi and
bacteria. The results indicate that these complexes exhibited good inhibitory
activity against tested bacteria and fungi compared to the standard drugs.

BOOK OF ABSTRACTS CHEM 08 (2020) Page 112