Fawaz A. Saad

Elaborated studies on nano-sized homo-binuclear Mn(II), Fe(III), Co(II), Ni(II), and Cu(II) complexes derived from N2O2 Schiff base, thermal, molecular modeling, drug-likeness, and spectral

Abstract A series of new homo-binuclear nano Mn(II), Fe(III), Co(II), Ni(II), and Cu(II) complexes were synthesized using a Schiff base ligand derived by condensation of p-phenylenediamine with 2-hydroxy-1-naphthaldehyde. The prepared complexes were characterized using elemental, thermal analyses, FTIR, 1HNMR, 13CNMR, UV–Vis, XRD, SEM, molar conductance, and magnetic moment measurements. FTIR spectral studies revealed the interaction of the ligand as bi-negative tetra-dentate towards Mn(II) and Fe(III) atoms, whereas the ligand molecule coordinates in neutral tetra-dentate mode towards Co(II), Ni(II), and Cu(II) ions. The geometries proposed are mainly octahedral configuration surrounds the central atoms referring to the electronic spectral data and magnetic measurements. The calculations abstracted from XRD patterns propose the nano-sized complexes. The SEM images show the nano-sized appearance of the particles except for the Ni(II)-complex. Thermo-gravimetric analysis was used to ensure the nature of the presence of solvent molecules attaching to the complexes. Molecular modeling was performed to assert the structural formula proposed for the ligand and some of its complexes. Also, drug-likeness was theoretically estimated to display the probable biological activity of the free ligand through a theoretical comparison with known drugs.

Synthesis, spectral, electrochemical and X-ray single crystal studies on Ni(II) and Co(II) complexes derived from 1-benzoyl-3-(4-methylpyridin-2-yl) thiourea

1-Benzoyl-3-(4-methylpyridin-2-yl) thiourea ligand was coordinated with Ni(II) and Co(II) perchlorate salts to isolate complexes. All the prepared compounds are deliberately investigated by all possible spectral tools. A comparative study for IR spectra reveals the neutral bidentate coordinating nature of the ligand towards the two metal ions. The UV/Vis spectra of the complexes display d-d transition bands proposed an octahedral geometry for the complexes. MS analysis data are concerned especially with the base peak which is corresponding to C28H25N6O2S2 M ion. The fragmentation patterns are relatively matched with each others. Electrochemical studies were carried out using platinum wire and Ag/AgNO3 as counter and reference electrodes, respectively. The data reflect the irreversible nature of the electrode couple and showed two successive one electron transfer process. X-ray single crystal studies are used to verifying the octahedral geometry proposed as well as calculating crystal parameters beside the structural refinements.

Co-ordinative properties of a tripodal trisamide ligand with a capped octahedral preference

An investigation into the co-ordination chemistry of tris(6-pivaloylamino-2-pyridylmethyl)amine (TPPA) shows a preference for capped octahedral geometry when no additional donors are present. This tripodal ligand yields capped octahedral complexes upon co-ordination to a series of first row transition metals when the counter-ion is a perchlorate, bromide or iodide ion. The exact geometry has been confirmed by shape mapping calculations. The largest variation from the capped octahedral geometry is observed in the case of nickel(ii), indicating a greater octahedral preference of this metal ion.

Co-ordination behaviour of a novel bisthiourea tripodal ligand: structural, spectroscopic and electrochemical properties of a series of transition metal complexes

The synthesis of a thiourea substituted derivative of tris(pyridyl-2-methyl)amine (TPA) is reported. Two of the three pyridine rings are substituted in the 6-position with benzoylthiourea groups. These thiourea groups undergo intramolecular hydrogen bonding to form six-membered rings which leaves one N-H group available to form hydrogen bonds with other molecules. This reports details how the complexation of this new ligand with transition metal ions yields complexes with differing geometries. Seven co-ordinate Mn(II) and Cd(II), six co-ordinate Ni(II) and five co-ordinate Co(II), Cu(II) and Zn(II) complexes have been isolated.

Spectral studies on a series of metal ion complexes derived from pyrimidine nucleus, TEM, biological and γ-irradiation effect.

A series of thiouracil complexes was prepared, all the prepared compounds are investigated by all possible tools. The ligand coordinates towards two central atoms as a neutral hexadentate mode. The octahedral structure was proposed with Ni(II), Pt(IV) and UO2(II) complexes. Square-pyramidal and square planar with VO(II) and Pd(II) complexes, respectively. VO(II) complex was irradiated by using Gamma radiation to through a light on the probability of geometry changes with the effect of radiation. The parameters calculated from ESR spectra before and after γ-irradiation reflect the rigidity of the complex towards the effect. Such may discuss the unaffected biological behavior before and after irradiation. XRD patterns were carried out to emphasis on the nature of the particles and the purity of products. The ligand, Pt(IV) and Pd(II) are found in nanometer range. TEM is a sensitive tool used to justify on the microstructure and surface morphology. All the investigated compounds are in nanorange. TG curves reflect a lower thermal stability of all investigated complexes due to the presence of water of crystallization. Finally, a toxic effect was observed with all investigated complexes towards Gram positive bacterium as well as a resistant behavior was observed with Gram negative bacteria.

Synthesis, characterisation and evaluation of a novel copper-64 complex with selective uptake in EMT-6 cells under hypoxic conditions

The radiometal (64)Cu is now widely used in the development of diagnostic imaging agents for positron emission tomography (PET). The present study has led to the development and evaluation of a novel chelating agent for (64)Cu: the new monothiourea tripodal ligand 1-benzoyl-3-{6-[(bis-pyridin-2-ylmethyl-amino)-methyl]-pyridin-2-yl}-thiourea (MTUBo). X-ray crystallographic analysis has shown this ligand forms a mononuclear complex with copper(II) and co-ordinates via a trigonal bipyramidal N4S array of donor atoms. Promisingly, cell uptake studies revealed that (64)Cu-MTUBo selectively accumulates in EMT-6 cells incubated under hypoxic conditions which may result from its relatively high Cu(II/I) redox potential. Small-animal PET imaging and ex vivo biodistribution studies in EMT-6 tumor bearing BALB/c mice revealed significant tumor uptake after 1 h p.i., yielding tumor-to-muscle (T/M) and tumor-to-blood (T/B) ratios of 8.1 and 1.1, respectively. However, injection of (64)Cu-acetate resulted in similar uptake indicating that the observed uptake was most likely non-specific. Despite showing high in vitro stability, it is likely that in vivo the complex undergoes transchelation to proteins within the blood in a relatively short timeframe. For comparison, the hypoxia imaging agent (64)Cu-ATSM was also evaluated in the same murine tumor model and showed about 60% higher tumor uptake than (64)Cu-MTUBo.

Elaborated spectral analysis and modeling calculations on Co(II), Ni(II), Cu(II), Pd(II), Pt(II), and Pt(IV) nanoparticles complexes with simple thiourea derivative

A series of metal complexes was synthesized using a simple thiourea derivative. The prepared complexes were characterized using different techniques (FTIR, ESR, X-ray diffraction [XRD], TG/DTA, and TEM). The FTIR spectrum of the ligand shows the presence of its tautomer forms (keto–enol). The ligand coordinates as a neutral bidentate in the Pt(IV), Pd(II), and Pt(II) complexes. In the case of Co(II) and Ni(II) complexes, the ligand is mono-negative bidentate. The proposed complexes are four to six coordinate. The geometries are proposed based on electronic spectral data and magnetic measurements and were verified using other tools. The XRD patterns reflect the nanocrystalline structures except for the Cu(II) complex, which is amorphous. The TEM images for platinum complexes show nanosize particles and homogeneous metal ion distribution on the complex surface. The EPR spectrum of Cu(II) complex verified the octahedral geometry of the complex. Molecular modeling was performed to assign the structural formula proposed for the ligand based on the characterization results. Transmission electron micrographs of the Pt(IV) complex; inset shows the magnified image.

Elaborated molecular docking and DFT/B3LYP studies for novel sulfa drug complexes, spectral and antitumor investigations

A new series of drug complexes from sulfa was prepared using Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Pt(II) ions. The isolated complexes are deliberately illustrated using spectral, thermal and different theoretical tools. The bidentate mode of coordination is proposed with all complexes. The octahedral configuration is the main structural formula proposed except d8 systems. Significant parameters derived from spectra were deducted to assert on the proposed configurations. XRD and TEM tools display a great conformity in-between for proposing the nano-crystallite sizes of all investigated compounds. Implementing Gaussian 09 program for structural formulas used to obtain the optimized forms. Applying DFT/B3LYP method, the frontier energy gaps were calculated and other important theoretical parameters. Utilizing molecular docking by AutoDock tools used to explain the experimental behavior of organic compounds toward the microorganisms from theoretical visualization. The docked complexes for 4ynu, 4d7h, 1zap, 1ecl, 3e5a, 1y0k and 1bqb protein receptors were investigated and the different energies were calculated. Pt(II), Zn(II) and Cu(II) complexes display significant inhibition for all microorganisms used in biological investigation. Moreover, the IC50 calculated represent the distinguish priority of Ni(II) and Co(II) complexes in overcoming liver cancer.

Simulative aurintricarboxylic acid molecular docking with antitumor activity for its VO(II), Cr(III), Mn(II) and Fe(III) complexes, HF/DFT modeling and elaborated EPR studies

A synthesized aurintricarboxylic acid (ATA) complex was deliberately investigated. Spectral, thermal, theoretical and antitumor studies are accomplished in this study. Elaborated electronic and EPR considerations are introducing parameters support the structural discussion of complexes. Octahedral geometry is proposed for all complexes except VO(II) is a square-pyramidal configuration. Molecular modeling utilizing Gaussian 09 program (HF/DFT) was used to verify the mode of bonding through the optimized geometries as well as essential quantum parameters were calculated using frontier energies (EHOMO & ELUMO). The soft character of the complexes may expect their excellent biological feature. The molecular docking computational achievement displays distinguished bounds of ATA drug with human colorectal carcinoma and human hepatic carcinoma. However, the interaction with human breast carcinoma receptor is completely absent. This behavior may clarify the antitumor activity of the complexes under investigation. The experimental work was supported with docking for carcinoma receptors used experimentally. VO(II) complex displays distinguished inhibition activity toward human carcinoma used. This is pointed to the other important use for ATA drug complexes exceeding the antibacterial field.

A Comparative Antimicrobial Study In Between a Quinoline Drug and Its Complexes: Spectral, Kinetic, and Molecular Modeling Investigations

A series of ciproH antibiotic drug complexes was prepared. The chosen metal ions have a great history in the medicinal field, which may introduce a sensitive antibiotic appearance in comparing with the free ciproH drug. All the prepared complexes are discussed based on spectral (IR, 1H NMR, 13C NMR, UV-vis, ESR, X-ray, and SEM), thermal, and analytical data. The ligand coordinates through its zwitterionic form as bidentate mode through COO− and C=O groups. The octahedral stereo structure was proposed for Cu(II), Zn(II), and Pt(IV) complexes, square planar with Pd(II) and Pt(II) complexes, and square-pyramidal with VO(II). The amorphous nature was proposed for all investigated complexes based on the X-ray diffraction patterns although, the nanocrystalline appearance of starting ligand. Thermogravimetric analysis is also used to support the presence or absence of solvent molecules conjugated with the complexes isolated physically or chemically. Applying Chem-office program, a suitable modeling structure of each investigated complex was drawn. A comparative antibacterial study was concerned using Gram –ve and Gram +ve bacteria. The data reflect the inhibiting effect of some complexes more than the drug itself, which is considered an introductory step in introducing competitive drug.