Rational synthesis, biological screening of azo derivatives of chloro-phenylcarbonyl diazenyl hydroxy dipyrimidines/thioxotetrahydropyrimidines and their metal complexes

Abstract

Herein, a new series of azo ligands HL-1 (5-(2-chloro-6-(phenylcarbonyl)phenyl)diazenyl)-6-hydroxydihydropyrimidines-2,4dione), HL-2 (5-(2-chloro-6-(phenylcarbonyl)phenyl)diazenyl)-6-hydroxy-2-thioxottetrahydropyrimidin-4one), HL-3 (5-(2,4-dichloro-6-(phenylcarbonyl)phenyl) diazenyl)-6-hydroxydihydropyrimidines-2,4dione), HL-4 (5-(2,4-dichloro-6-(phenylcarbonyl) phenyl)diazenyl)-6-hydroxy-2-thioxotetrahydropyrimidin-4one) and their metal complexes with Cu(II) & Ni(II) were synthesized successfully having excellent yield, in reproducible conditions and for structure elucidation different advance spectroscopic techniques (FTIR, ¹H NMR, ¹³C NMR and Mass Spectrometry) were applied. In FTIR analysis, the absence of peak at 3450-3550 cm ^-1 due to -NH₂ and presence of a new peak of N=N at 1390-1520 cm^-1 confirmed synthesis of the ligands. The ¹H NMR spectra of azo ligands showed singlet peak at 11.5-13.5 ppm (Ar-OH) for hydroxyl group and -NH₂ signals disappearance of anilines at 4-5 ppm also gives strong indication for the synthesis of azo compounds. On complexation two most important peaks (M-O, M-N) appeared in all the metal chelates in the range of 400-600 cm^-1 which were not present in any of the ligands, confirmed the formation of complexes. Molecular ion peaks in mass spectra at 273, 388, 407 and 423 m/z value for ligands as well as for complexes at 803, 835, 871 and 904 m/z also give strong indication that proposed ligands and their metal complexes are produced successfully. Biological screening of the synthesized compounds were also carried out against different bacterial strains (E.coli, S.typhi, and B.subtilis), antifungal (C.albicans, A.niger, and C.glabrata) strains and antioxidant activity. From results it was observed that HL-4 and Cu complexes exhibited maximum inhibition against all bacterial and fungal strains as compared to other ligands and standard drug.

Keywords: Antimicrobial agents; Antioxidant; Azo compounds; Metal complexes.

Graphical abstract

Scheme 1

Synthetic Route of Azo Ligands.

Figure 1

a) FTIR spectrum of ligand HL-1. b) 1HNMR spectrum of ligand HL-1. c) C13 NMR spectrum of ligand HL-1. d) Mass spectrum of ligand HL-1.

Scheme 2

Synthetic Route of Metal Complexes.

Figure 2

FTIR spectrum of HL1-Cu.

Figure 3

Mass spectrum of HL1-Cu.

Scheme 3

Mass fragmentation pattern of ligand HL-1.

Scheme 4

Mass fragmentation pattern of L1-Cu.