Study of the chemical structure and their nematicidal activity of N₂O₂ tetradentate Schiff base metal complexes

Abstract

Coordination compounds of Cu (II), Y (III), Zr (IV) and La (III) with the tetradentate Schiff base (H 2 L) obtained through the condensation of pphenylenediamine with salicylaldehyde under reflux conditions. The complexes were characterized by elemental analysis, magnetic susceptibility, molar conductance and also, with various spectroscopic techniques such as 1 H NMR, UV-Vis., IR and XRD techniques. Electrolytic nature of complexes was ascertained by molar conductance values. In these four complexes, the ligand chelates act in a tetradentate manner via azomethine nitrogen and oxygen atoms of phenolic groups. Electronic spectroscopic data are in agreement with an octahedral geometrical structure. Thermal degradation analyses in nitrogen gas were used to investigate the number and location of water molecules. The chemical formulae of metal complexes were confirmed by microanalytical data. The activation thermodynamic parameters, such as, E * , ΔH * , ΔS * and ΔG * were calculated from the DTG curves using Coats Redfern (CR) andHorowitz-Metzeger (HM) methods at n = 1 or n ≠ 1. Nematicidal activities indicate that the ligand exhibit greater activity when compared to its complexes. In addition metal complexes displayed good moderate nematicidal activities.

Study on the nematicidal activity and chemical structure of NO bidentate Schiff base some metal complexes

“…The υ(M–O) and υ(M–N) bands were observed at 571, 523, and 485 cm −1 for complex ( 1 ), 562, 460, and 424 cm −1 for complex ( 2 ), 584, 496, and 445 cm −1 for complex ( 3 ), 652 and 455 cm −1 for complex ( 4 ), 579, 528, 487, and 446 cm −1 for complex ( 5 ) and 600, 553, 495 and 437 cm −1 for complex ( 6 ), which are absent in the spectrum of the free ligand (Table ). According to the infrared spectra, it is concluded that L behave as bidentate ligand through carboxylic and azomethine nitrogen groups as coordinate sites (Schemes and ) . ν(Zr = O) was found as a medium band at 875 cm −1 (Figure S1).…”

Ligational, density functional theory, and biological studies on some new Schiff base 2‐(2‐hydroxyphenylimine)benzoic acid (L) metal complexes

“…[ 19,20 ] Qualitative reaction revealed the presence of chloride and sulfate as counter ions in good agreement with molar conductivity. [ 21,22 ] Magnetic moments of the complexes were measured at room temperature; the data indicate that complexes (A) and (B) possess a paramagnetic character in high‐spin/low‐field octahedral geometry with a lower energy gap between t 2g and e g and with the effective values 4.7 and 3.12, [ 18,23 ] respectively.…”

Spectroscopic, thermal analyses, XRD spectra and nematicidal activity study of some new N2O2 tetradentate Schiff base metal ions complexes

“…The ν(M-O) and ν(M-N) bands observed at 658, 589 and 472 cm -1 for complex (A), 676, 599, 551, 513 and 483 cm -1 for complex (B), at 656, 602, 517 and 472 cm -1 for complex (C), at 654, 592 and 469 cm -1 for complex (D), at 657, 589, 518 and 472 cm -1 for complex (E) and 648, 605, 531 and 494 cm -1 for complex (F) which are absent in the spectrum of free HL. Therefore, it is concluded that all the IR data suggested that the metal was bonded to the Schiff bases through the phenolic oxygen and the C=N nitrogen [28,29] and oxygen of carbonyl group involved in the coordination sphere, therefore HL behave as tridentate ligand. The data showed that ν(Zr=O) is a medium band at 887 cm -1 and the ν as (U=O) and ν s (U=O) absorption bands occurs as very strong at 901 and medium at 830 cm -1 , respectively [30,31].…”