Synthesis, spectroscopic and antimicrobial studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes derived from benzoic acid bidentate Schiff base ligand

The Schiff base was synthesized by condensation of 2-hydroxy-1-naphthaldehyde with 3- aminobenzoic acid in 1:1 molar ratio. The Schiff base ligand formed complexes with Co (II), Ni (II), Cu (II) and Zn (II) acetate via mechanochemical synthesis. The synthesized compounds were characterized by solubility test, thermal analysis, FT-IR, powder x-ray diffraction, molar conductance measurement, magnetic susceptibility and elemental analysis. The Schiff base has a melting point of 190 oC. The decomposition temperature of complexes was found to be in the range 289 – 302 oC. The Schiff base and its metal (II) complexes were soluble in DMF, DMSO and sparingly soluble in acetonitrile, chloroform, diethyl ether and insoluble in n-hexane which indicate the polar nature of the synthesized compounds. The IR spectral analysis of the free Schiff base shows a band at 1622 cm-1, assigned to v(C=N) stretching vibrations. This band was shifted in the spectra of complexes (1607 – 1633 cm-1), indicating coordination of the Schiff base to the metal ion through the azomethine group. The molar conductance of complexes determined are in the range 9.51 – 14.87 Ohm-1cm2mol-1 which indicate the non-electrolytic nature in DMF. Magnetic susceptibility measurements of Co (II), Ni (II) and Cu (II) complexes exhibit a magnetic moment in the range 1.25 – 3.08 BM. The values correspond to square-planar geometry. The magnetic moment value of Zn (II) complex indicates a diamagnetic behaviour. The elemental analysis of the complexes for C, H and N determined showed that the observed and the calculated percentages of the elements are in good agreement.

Heterotridentate organodiphosphines in Pt(η3-P1X1P2)(Y) (X1 = B, S, or Si) and Pt(η3-P1P2Si1)(Y) derivatives-structural aspects

This review covers almost 30 Pt(II) complexes of the composition Pt(η3-P1X1P2)(Y), (X1 = BL, SL, or SiL), (Y = H, OL, NL, CL, Cl, PL, or I) and Pt(η3-P1P2Si1)(CH3). Heterotridentate ligands form six types of metallocyclic rings: P1CNB1NCP2, P1C2S1C2P2, P1C2Si1C2P2, (most common), P1CNSi1NCP2, and P1C3Si1C3P2 with common B1, S1, or Si1 atoms. In P1C2P2C3Si1 the P2 atom is common. The structural data (Pt–L, L–Pt–L) are analyzed and discussed with an attention to the distortion of a square-planar geometry about Pt(II) atoms as well as trans-influence. The sum of Pt–L(x4) bond distances growing with covalent radius of the X1 and Y atoms.

Theories on the Formation and Evolution of ~2D Planar Celestial Kinematics

The existence of essentially 2-dimensional planar solar systems and galaxies would seem to be a contradiction to the 2nd Law of Thermodynamics relating to the tendency of natural processes toward spatial homogeneity of matter and energy. During the formation process of celestial systems, an equal dispersion of matter throughout 3-dimensional space would have been a more logical result to satisfy entropy/disorder increasing at all times. Conventional belief is that the ~2D planar geometry of galaxies and solar systems is largely due to rotational kinetic forces and matter collapsing due to its own gravity; this project seeks to expand and enhance the potential forces to explain ~2D planar celestial kinematics. Computational mathematics utilizing programming in C# will analyze various potential forces and relative magnitudes to determine proposed force-balances during these formation processes. A better understanding of the formation process (and the forces that govern them) of galaxies and solar systems can help explain their evolutions to steady state; for this, the derived mathematical models will be computed and translated to visual models in 4-D space-time over various time frames.

Adsorptive Recovery of Cu2+ from Aqueous Solution by Polyethylene Terephthalate Nanofibres Modified with 2-(Aminomethyl)Pyridine

The accumulation of plastic waste products in the environment has adversely affected wildlife and human beings. Common plastics that accumulate in the environment are plastics that are made of polyethylene terephthalate (PET) polymer. PET plastic waste products can be recycled for beneficial use, which would reduce their negative impacts. In this study, modified PET or waste PET (WPET) from plastic bottles was blended with powder commercial 2-(aminomethyl)pyridine (SiAMPy) resin and electrospun into composite nanofibres and applied for Cu2+ adsorption. PET-SiAMPy or WPET-SiAMPy composite nanofibres fibre diameters from the HRSEM images were 90–140 nm and 110–155 nm, respectively. In batch adsorption experiments, PET-SiAMPy or WPET-SiAMPy composite nanofibres achieved Cu2+ adsorption equilibrium within 60 secs of contact time with 0.98 mmol/g (89.87%) or 1.24 mmol/g (96.04%) Cu2+ adsorption capacity. The Cu2+ complex formation rate (k) with WPET-SiAMPy was 0.0888 with the mole ratio of Cu2+ and WPET-SiAMPy nanofibres 1:2. The complex molecular formula formed was Cu(WPET-SiAMPy)2 with a square planar geometry structure. The WPET-SiAMPy nanofibres’ adsorption was best fitted to the Freundlich isotherm. WPET-SiAMPy composite nanofibres were considered highly efficient for Cu2+ adsorption from aqueous solution and could be regenerated at least five times using 5 M H2SO4.

Four Isostructural 3d-4f Mixed Metal Organic Frameworks and Their Magnetic Properties

Four new isostructural 3d-4f mixed metal organic frameworks (MOFs) Cu Gd2 (BDC)4, compound 1, Cu Ho2 (BDC)4, compound 2, Cu Eu2 (BDC)4, compound 3, and Cu Dy2 (BDC)4, compound 4 were successfully synthesized. The structure, stability, and magnetic properties were analyzed. Each MOF has two lanthanide ions and one copper ion node with terephthalic acid as the organic linker. The lanthanide ions form a dimer with each having a capped trigonal prismatic geometry while the copper ion has a square planar geometry. Each of these MOFs shows varying degrees of antiferromagnetic interactions.

Experimental and Quantum Mechanical Investigation of N-heterocyclic Carbene Palladium Complex: Synthesis and Antibacterial Activity

In this study, we report the synthesis, characterization, and biological activity of Pd-NHC-PEPPSI complex 2a. Further confirmations of structural details were provided by a single-crystal X-ray. A single crystal of 2a shows that the coordination geometry around Pd slightly distorted square-planar geometry. Intermolecular interactions have been studied through the NBO analyses. Structural parameters and spectroscopic properties of the complexes are well interpreted by DFT and TD-DFT calculations. Moreover, the complex 2a showed a remarkable antimicrobial effect against Micrococcus luteus LB 14110mm, Listeria monocytogenes ATCC 19117, Salmonella typhimurium ATCC 14028, Staphylococcus aureus ATCC 6538, Pseudomonas aeruginosa, and Candida albicans.

Galvanostatic Intermittent Titration Technique Reinvented: Part I. A Critical Review

The galvanostatic intermittent titration technique (GITT), introduced in 1977 by Weppner and Huggins, provided a readily accessible means to measuring the chemical diffusion coefficient of electrochemical electrode materials. The method continues to be widely used today, but the reported diffusivity values are highly inconsistent, ranging as much as four orders of magnitude for some Li layered oxide compositions. Even qualitative trends of diffusivity are inconsistent, suggesting significant flaws in the implementation of the method. Other variants of the GITT method also suffer from similar inconsistency problems. Here we identify numerous sources of significant error including composition-dependent reaction overpotentials, mathematical flaws in the relaxation analysis methods, finite-size and non-planar geometry effects, inter-particle inhomogeneity issues, early transient effects, and surface area uncertainties. We propose a simple relaxation analysis scheme using the time variable t relax + τ − t relax , where t relax is relaxation time and τ is the galvanostatic pulse duration. We also propose to use dense diffusion-limited samples to isolate the bulk-diffusion process in the time domain. Chemical diffusivity can be extracted much more reliably with this improved implementation of the GITT method.

Mononuclear and Tetranuclear Copper(II) Complexes Bearing Amino Acid Schiff Base Ligands: Structural Characterization and Catalytic Applications

Two new glycine-Schiff base copper(II) complexes were synthesized. Single crystal X-ray diffraction (SCXRD) allowed us to establish the structure of both complexes in the solid state. The glycine-Schiff base copper(II) complex derived from 2′-hydroxy-5′-nitroacetophenone showed a mononuclear hydrated structure, in which the Schiff base acted as a tridentate ligand, and the glycine-Schiff base copper(II) complex derived from 2′-hydroxy-5′-methylacetophenone showed a less common tetranuclear anhydrous metallocyclic structure, in which the Schiff base acted as a tetradentate ligand. In both compounds, copper(II) had a tetracoordinated square planar geometry. The results of vibrational, electronic, and paramagnetic spectroscopies, as well as thermal analysis, were consistent with the crystal structures. Both complexes were evaluated as catalysts in the olefin cyclopropanation by carbene transference, and both led to very high diastereoselectivity (greater than 98%).

Angular momentum redirection phase of vector beams in a non-planar geometry

An electric field propagating along a non-planar path can acquire geometric phases. Previously, geometric phases have been linked to spin redirection and independently to spatial mode transformation, resulting in the rotation of polarisation and intensity profiles, respectively. We investigate the non-planar propagation of scalar and vector light fields and demonstrate that polarisation and intensity profiles rotate by the same angle. The geometric phase acquired is proportional to j = ℓ + σ, where ℓ is the topological charge and σ is the helicity. Radial and azimuthally polarised beams with j = 0 are eigenmodes of the system and are not affected by the geometric path. The effects considered here are relevant for systems relying on photonic spin Hall effects, polarisation and vector microscopy, as well as topological optics in communication systems.