Synthesis, characterization and biological study of Cu(II) complexes of aminopyridine and (aminomethyl)pyridine Schiff bases

Abstract

The synthesis, characterization and antimicrobial activity determination of some aminopyridine-and (aminomethyl)pyridine-salicylaldimine copper(II) complexes were realized. The ligands, L 1-L 6 , were prepared by condensing salicylaldehyde and o-vanillin with 2-and 3-amino-and (aminomethyl)pyridine, respectively. The complexes were characterized by micro-analytical, electronic, infrared and conductivity data. The structures of the Schiff base ligands were further confirmed from 1 Hand 13 C-NMR spectral data. This study established that salicylaldimine ligands could coordinate as neutral species via the imine-N and the undeprotonated phenolic-O. The complexes have the molecular formula: [CuLCl], [Cu(LH) 2 Cl 2 ]•xH 2 O or [Cu(LH)Cl(H 2 O)]Cl. The X-ray crystal structure of [CuL 6 Cl] indicated a square planar geometry with the Schiff base ligand coordinated to the Cu(II) ion as a tridentate monobasic, N 2 O, ligand. The crystals crystallized in a monoclinic system with P2 1 /c space group. All the ligands and their Cu(II) complexes were screened for their antimicrobial activity against Staphylococcus aureus subsp. aureus ATCC ® 6538™  , Bacillus subtillis subsp. spizizenii ATCC ® 6633™  , Escherichia coli ATCC ® 8739™  and Candida albicans ATCC ® 2091™  using agar diffusion and broth dilution techniques. The presence of the methoxyl group enhanced the antimicrobial activity of the salicylaldimine Schiff base ligands.

Metal Complexes of Heterocyclic Sulphonamide: Synthesis, Characterization and Biological Activity

“…The coordination of imine to zinc (II) ion was assigned to the vibration frequency band of 1674.30cm -1 and that of the nickel (II) was assigned to the vibration frequency band of 1615.12 cm -1 . This observation corroborates the azomethine (C = N) frequency range of 1683.41 -1575 cm −1 estimated by Jisha and Isac Sobana raj, [7] and Sobola & Watkins, [23]. Other important frequency bands of the ligand and their complexes are shown in Table 3.…”

“…The absorption band at 224-200 nm corresponds to the π → π* transition of the benzene rings, and the absorptions at 290-253 nm and 341-300 nm were assigned to the π → π* of the double-bonded carbons and n → π* transitions and the azomethine group (HC=N) of 2aminopyridine respectively. The prominent band at 330 nm is associated with ligand -metal charge transfer of Cu (II) complex and the broadband at the 599 nm region corresponds to the d−d transition of the Cu(II) complexes [23,24]. The band at 334.09-375.25 nm was assigned to ligand-metal charge transfer transition (LMCT) of iron (II) complex and the broad electronic band at 612 nm region corresponds to the d-d transition of the Iron (II) complex [4,23].…”

“…The prominent band at 330 nm is associated with ligand -metal charge transfer of Cu (II) complex and the broadband at the 599 nm region corresponds to the d−d transition of the Cu(II) complexes [23,24]. The band at 334.09-375.25 nm was assigned to ligand-metal charge transfer transition (LMCT) of iron (II) complex and the broad electronic band at 612 nm region corresponds to the d-d transition of the Iron (II) complex [4,23].…”

Spectral Analysis and In vitro Biological Activity of Cu(II) Complex with Tridentate ONO Schiff Base Ligand

“…Although the Schiff bases are known to be good chelating agents, and easily prepared and characterized, little interest has been given to their uses for analytical purposes because of two serious drawbacks, they are insoluble in aqueous solutions and they decompose easily in acidic solutions, limiting their use to basic conditions [5]. Schiff bases and its metal complexes also exhibit a wide variety of biological activities, including antifungal, antibacterial, antitumor, anti-inflammatory, trypanocidal, anti-HIV, antimalarial, and anti-urease activities [6][7][8][9][10][11][12][13][14][15][16]. The imine group present in these compounds is critical for their biological activities, and thus that moiety has been extensively explored for the development of new bioactive substances [6].…”

Synthesis, Characterization, and Biological Evaluation of a New Hydrogen-Bonded Charge-Transfer Complex of 2-Amino-4-methoxy-6-methylpyrimidine

“…Moreover, some aminopyrimidine derivatives have been explored as antithrombus, antimicrobial, antifungal, and anti-HIV agents [19][20][21]. ey also form a range of organometallic complexes with anticancer and antioxidant activities [22][23][24]. Aminopyrimidines contain important groups that can act as electron donors or proton acceptors, and the study of their CT complexes helps to understand the nature of their CT interactions [25,26].…”