Coordination Behavior of N‐Donor Schiff Base Derived from 2‐Benzoylpyridine Toward Mn(<scp>II</scp>), Co(<scp>II</scp>), Ni(<scp>II</scp>), Cu(<scp>II</scp>), Zn(<scp>II</scp>), Pd(<scp>II</scp>), and Cr(<scp>III</scp>) Metal Ions: Synthesis, Spectroscopic and Thermal Studies, and Biological Activity

Tolan

El‐Nahas

2020

A new series of transition‐metal complexes of Schiff base ligand containing the amino mercapto triazole moiety (HL) was prepared. The Schiff base and its metal complexes were elucidated by different spectroscopic techniques (infrared [IR], 1H nuclear magnetic resonance, UV–Visible, mass, and electron spin resonance [ESR]), and magnetic moment and thermal studies. Quantum chemical calculations have been carried out to study the structure of the ligand and some of its complexes. The IR spectra showed that the ligand is chelated with the metal ion in a neutral, tridentate, and bidentate manner using NOS and NO donors in complexes 1–6, 10–12, and 7 and 8, respectively, whereas it behaves in a monobasic tridentate fashion using NOS donor sites in copper(II) nitrate complex (9). The magnetic moment and electronic spectra data revealed octahedral and square pyramidal geometries for complexes 2, 11, 12, and 5–8 and 10, respectively. However, the other complexes were found to have tetrahedral (4), trigonal bipyramidal (1 and 3), and square planar (9) structures. Thermal studies revealed that the chelates with different crystallized solvents undergo different types of interactions and the decomposition pathway ended with the formation of metal oxygen (MO) and metal sulfur (MS) as final products. The ESR spectrum of copper(II) complex 10 is axial in nature with hyperfine splitting with 2B1g as a ground state. By contrast, complexes 7 and 8 undergo distortion around the Cu(II) center, affording rhombic ESR spectra. The HL ligand and some of its complexes were screened against two bacterial species. Data showed that complex 12 demonstrated a better antibacterial activity than HL ligand and other chelates.

Section: Resultsmentioning

confidence: 86%

Section: Resultsmentioning

confidence: 97%

Synthesis, structural, spectroscopic, and thermal studies of some transition‐metal complexes of a ligand containing the amino mercapto triazole moiety

Tolan

El‐Nahas

2020

“…But, the additional bands observed at (1462, 1442); 1402; (1065, 1030) cm −1 are restricted to asymmetric, symmetric bending vibrations of (CH 3 ) groups and aromatic (C–H) in‐plane deformation . Moreover, the HL spectrum exhibits strong and medium bands at (1722, 539); 1659; (1603,1571); 1497; (999) and (945, 1091 cm −1 ) assignable to different vibrations of lactone carbonyl (C=O); ν(C=N) of azomethine group; (ν(C=C) + ν(C=N)) of pyridine; ν(C=N) of pyrazolopyridine; ν(C–O–C) of pyrane ring and ν(N–N), respectively . Finally, the spectrum depicts weak to medium bands at 621 and 505 cm −1 which are denoted to (C–H) in‐plain and out‐of‐plane bending of pyridine ring overlapped with ρ(NH) of pyrazolopyridine, respectively …”

Section: Resultsmentioning

confidence: 96%

“…The methyl protons appeared at δ (2.49–2.61 ppm) on complexation. In addition, the spectrum of complex depicts a broad signal at δ (3.75 ppm) attributed to protons of crystallized water …”

Section: Resultsmentioning

confidence: 99%

“…This is indicative of the formation of Schiff base ligand (Scheme ). The spectrum of the ligand displays spectral bands at (3451, 1156, 800); 1361 cm −1 cm −1 and (1311, 1258, 1199) cm −1 , assigned to protonated hydroxyl group (ν(OH), δ(OH), γ(OH)); ν(C–N) of arylazomethine, and phenolic ν(C–O), respectively . These vibrational bands are taken as evidence for the presence of HL ligand in enol‐imine form (Figure c) rather than di‐keto and keto‐enamine forms (Figure a, b, d) .…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Structural characterization, thermal investigation and biological activity of metal complexes containing Schiff Base ligand (Z)‐3‐(1‐((4,6‐dimethyl‐1H‐pyrazolo[3,4‐b] pyridin‐3‐yl)imino)ethyl)‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one

Abouel‐Enein

Abdel‐Satar

2019

A new series of metal complexes containing Co(II), Pd(II), Fe(III) chloride and Cu(II) salts (chloride, bromide, sulphate and perchlorate) have been prepared with Schiff base ligand (HL). The synthesized compounds were elucidated using elemental analyses, spectral techniques, molar conductance, magnetic measurements and thermogravimetric studies. The analytical data established (1 M:1 L) stoichiometry for complexes (1), (2), (4), (6) and (7) as well as (1 M:2 L) and (2 M:3 L) stoichiometry for complexes (5) and (3), respectively. As a result, the ligand HL coordinates in complexes (1), (2), (4), (6) as a monobasic tridentate ONN moiety via the oxygen atom of the deprotonated phenolic OH, the nitrogen atoms of the azomethine and the imine group in pyrazolopyridine ring. While, it behaves as a neutral bidentate in complexes (3,7), chelates via oxygen and nitrogen atoms of enolic OH and azomethine groups. Also, in complex (5) Cu2+ ion binds via NO sits of two ligand molecules in its monobasic and neutral forms. The magnetic moment and electronic spectral data proposed octahedral structure for complexes (2, 3 and 7) as well as triagonal bipyramidal and square pyramidal geometry for complexes (1 and 4), while, chelates (5) and (6) possess square planar geometry. TG/DTG studies confirmed the chemical formula for these complexes and established the thermal decomposition processes ended with the formation of metal or metal oxides contaminated with carbon residue. An axial electron spin resonance spectra were suggested for Cu(II) complexes pointing to 2B1g as a ground state with hyperfine structure for complex (4). In vitro antibacterial and antioxidant activities were performed for HL ligand and its metal complexes. The biological studies indicate that complex (3) has better antibacterial activity compared to the ligand and the other complexes.

Synthesis, spectral characterization, thermal studies and biological activity of (Z)‐5‐((1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)diazenyl)‐6‐hydroxy‐2‐mercaptopyrimidin‐4(3H)‐one and its metal complexes

Abouel‐Enein

Abouzayed

2017

Z)-5-((1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)diazenyl)-6hydroxy-2-mercaptopyrimidin-4(3H)-one (H 3 L) was exploited as a ligand for the synthesis of a series of metal complexes, where the metal was Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pd(II), Cr(III) and Ru(III). The structural features of the ligand and the synthesized complexes were characterized using various analytical, spectral and thermal measurements. Infrared spectra showed that the ligand coordinates to all metal ions in a neutral keto-enol-thiol manner. It behaves in a tetradentate fashion in all binuclear complexes except the Cr(III) complex, where it is hexadentate, and in a tridentate fashion in mononuclear complexes. The azo group participates in chelation only in the case of binuclear complexes. All complexes exhibit octahedral geometry except Pd(II) and Cu(II) acetate which are square planar and square pyramidal, respectively. Kinetic parameters were computed from thermal decomposition data. Axial electron spin resonance spectra were obtained for Cu(II) complexes indicating (d x 2 −y 2 ) 1 as a ground state with small g || values affording strong interaction between the ligand and metal ions. The biological measurements reveal that the ligand has antioxidant activity relative to the metal complexes, while the metal complexes have cytotoxicity in comparison to the free ligand. KEYWORDSantioxidant and anticancer activity, azodye ligand, metal complexes, spectral methods, thermal studies