New Schiff base ligand and its novel Cr(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II) complexes: spectral investigation, biological applications, and semiconducting properties.

New Schiff base ligand, derived from antiviral valacyclovir, and its novel Cr(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II) complexes have been synthesized. By using a variety of analytical and spectroscopic techniques, the type of bonding between the ligand and the metal ions in the recently formed complexes was clarified. The Schiff base ligand act as a bidentate and coordinated with the metal ions through the azomethine-N and the phenolic-O centers, in a mono-deprotonated form. Except for the Zn(II) complex, which displayed a tetrahedral geometry, all complexes displayed octahedral geometry. The TGA findings supported that the stability and decomposition properties of the metal complexes were entirely distinct from one another. The thermogram showed decomposition of all investigated metal complexes above 200 °C in three, four or five steps, and indicated the high thermal stability of these complexes. According to XRD patterns, the particles of these complexes were located at the nanoscale. Moreover, for all the samples analyzed, the TEM images showed uniform and homogeneous surface morphology. The biological activity revealing the high efficiencies of the screened complexes as antibacterial and antitumor agents. The antimicrobial activity of the ligand and its complexes was examined against a variety of pathogenic bacteria and fungi including Escherichia coli, Staphylococcus aureus and Candida albicans. The data obtained revealed that the metal ion in the complexes enhanced the antimicrobial activity compared to the free ligand. The high efficiencies toward S. aureus, E. coli, and C. albicans appeared by Cu(II) complex 23, Ni(II) complex 20, and Ni(II) complex 19, respectively. The antitumor activity of the ligand and its complexes was tested against Hepatocellular carcinoma cell line (HepG-2 cells), the residue 28 which produced after heating the Cu(II) complex 25 at 200 °C for 1 h, exhibited strong inhibition of HepG-2 cell growth. The results of the DNA cleavage investigation demonstrated the ability of investigated Cu(II) complex to degrade DNA. The docking findings showed strong interactions of both the ligand and its examined Cu(II) complex, revealing their ability to cleavage DNA and their potent inhibitory effects on tumor cells. The electrical conductivity study confirmed that the ligand and its investigated complexes had semiconducting properties.

Mono- and binuclear copper(II) complexes of new hydrazone ligands derived from 4,6-diacetylresorcinol: Synthesis, spectral studies and antimicrobial activity.

Two new hydrazone ligands, H2L(1) and H2L(2), were synthesized by the condensation of 4,6-diacetylresorcinol with 3-hydrazino-5,6-diphenyl-1,2,4-triazine and isatin monohydrazone, respectively. The structures of the ligands were elucidated by elemental analyses, IR, (1)H NMR, electronic and mass spectra. Reactions of the ligands with several copper(II) salts, including AcO(-), NO3(-), SO4(2-), Cl(-) and Br(-) afforded mono- and binuclear metal complexes. Also, the ligands were allowed to react with Cu(II) ion in the presence of a secondary ligand (L') [N,O-donor; 8-hydroxyquinoline, N,N-donor; 1,10-phenanthroline or O,O-donor; benzoylacetone]. Characterization and structure elucidation of the prepared complexes were achieved by elemental and thermal analyses, IR, electronic, mass and ESR spectra as well as conductivity and magnetic susceptibility measurements. The ESR spin Hamiltonian parameters of some complexes were calculated. The spectroscopic data showed that the H2L(1) ligand acts as a neutral or monobasic tridentate ligand while the H2L(2) ligand acts as a bis(monobasic tridentate) ligand. The coordination sites with the copper(II) ion are phenolic oxygen, azomethine nitrogen and triazinic nitrogen (H2L(1) ligand) or isatinic oxygen (H2L(2) ligand). The metal complexes exhibited octahedral and square planar geometrical arrangements depending on the nature of the anion. The ligands and some metal complexes showed antimicrobial activity.

Mono, bi- and trinuclear metal complexes derived from new benzene-1,4-bis(3-pyridin-2-ylurea) ligand. Spectral, magnetic, thermal and 3D molecular modeling studies.

New bis (pyridylurea) ligand, H2L, was synthesized by the reaction of ethylpyridine-2-carbamate (EPC) and p-phenylenediamine. The ligand was characterized by elemental analysis, IR, (1)H NMR, electronic and mass spectra. Reaction of the prepared ligand with Co(2+), Ni(2+), Cu(2+), Fe(3+), VO(2+) and UO2(2+) ions afforded mono, bi- and trinuclear metal complexes. Also, new mixed ligand complexes of the ligand H2L and 8-hydroxyquinoline (8-HQ) with Co(2+), Ni(2+), Cu(2+) and Fe(3+) ions were synthesized. The ligand behaves as bi- and tetradentate toward the transition metal ions, coordination via the pyridine N, the carbonyl O and/or the amidic N atoms in a non, mono- and bis-deprotonated form. The complexes were characterized by elemental and thermal analyses, IR, electronic and mass spectra as well as conductance and magnetic susceptibility measurements. The results showed that the metal complexes exhibited different geometrical arrangements such as square planar, tetrahedral, octahedral and square pyramidal arrangements. The Coats-Redfern equation was used to calculate the kinetic and thermodynamic parameters for the different thermal decomposition steps of some complexes. 3D molecular modeling of the ligand, H2L and a representative complex were studied.

A new bioactive Schiff base ligands derived from propylazo-N-pyrimidin-2-yl-benzenesulfonamides Mn(II) and Cu(II) complexes: synthesis, thermal and spectroscopic characterization biological studies and 3D modeling structures.

New series of Schiff base ligand H(2)L and their Cu(II) and Mn(II) complexes derived from azosulfapyrimidine were synthesized and characterized by elemental and thermal studies conductance measurements IR, electronic and EPR spectra. 3D modeling of the ligand indicate that azo group does not participate in complex formation and surface potential on one of the ligand under study indicate that electron density around azomethine groups are much higher than the azo group therefore coordination takes place around azomethine groups. The variety in the geometrical structures depends on the nature of both the metal ions and the Schiff base ligands. The thermo kinetic parameters are calculated and discussed. The biological activities of the ligands and complexes have been screened in vitro against some bacteria and fungi to study their capacity to inhibit their growth and to study the toxicity of the compounds.

Tetra- and hexadentate Schiff base ligands and their Ni(II), Cu(II) and Zn(II) complexes. Synthesis, spectral, magnetic and thermal studies.

Tetradentate N(2)O(2), N(4) Schiff bases, 1,2-bis(4-oxopent-2-ylideneamino) benzene (BOAB), 1-(4-oxopent-2-ylideneamino-2-[(2-hydroxyphenyl)ethylideneamino] benzene (OAHAB), 7,16-bis(4-chlorobenzylidene)-6,8,15,17-tetra-methyl-7,16-dihydro -5,9,14,18-tetraza-dibenzo[a,h] cyclo tetradecene (BCBDCT), 7,16-bis(2-hydroxy-benzylidene)-6,8,15,17-tetramethyl-7,16-dihydro-5,9,14,18-tetraza-dibenzo [a,h] cyclo tetradecene (BHBDCT) and hexadentate N(4)O(2) Schiff bases, 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(2-hydroxybenzylidene) pentane (BHAPHP), 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(4-chlorobenzylidene) pentane (BHAPCP) were prepared and characterized by elemental analysis, IR, UV-Vis, (1)H NMR and mass spectra. The solid complexes of the prepared Schiff base ligands with Ni(II), Cu(II) and Zn(II) ions were isolated and characterized by elemental and thermal analyses, IR, electronic and ESR spectra as well as conductance and magnetic susceptibility measurements. The results showed that most complexes have octahedral geometry but few can attain the tetrahedral arrangement. The TG analyses suggest high stability for most complexes followed by thermal decomposition in different steps. The kinetic and thermodynamic parameters for decomposition steps in Cu(II) complexes thermograms have been calculated.