trans-Diaqua-bis[5-carb-oxy-2-(3-pyrid-yl)-1H-imidazole-4-carboxyl-ato-κN,O]iron(II)

Production of an environmentally stable anti-corrosion film based on Esfand seed extract molecules-metal cations: Integrated experimental and computer modeling approaches

This study aims at finding a suitable alternative for traditional and hazardous organic/inorganic corrosion inhibitors. In this study, the aqueous extract of Esfand seed (ESE) was used as a unique green source of nitrogen-based organic compound with great capability of the steel corrosion inhibition in a saline solution. Surface and electrochemical analyses were carried out by Ultraviolet-visible spectroscopy (UV), Fourier-transform infrared spectroscopy (FT-IR), Grazing incidence X-ray diffraction (GIXRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS), and polarization methods. Furthermore, the adsorption of inhibitors on the steel surface was explored by Monte Carlo (MC), molecular dynamics (MD) and quantum mechanics (QM) methods. The electrochemical studies established the effectiveness of the zinc cations addition to the ESE containing solution on its inhibition efficiency. The sample inhibited by 300 ppm ESE + 700 ppm Zn showed the highest anti-corrosion properties. The inhibition efficiency of this sample was reached 98.8% after 264 h which is much higher than those reported in the previous studies. QM computations proved the formation of complexes via donor-acceptor action. MC and MD simulations supported the inhibitors adsorption on the steel.

Synthesis and reactivity of a 4His enzyme model complex

A new iron(II) complex has been prepared and characterized. [Fe(TrIm)4(OTf)2] (1, TrIm = 1-Tritylimidazole). The solid state structure of 1 has been determined by X-ray crystallography. Compound 1 crystallizes in triclinic space group P1̄, with a = 13.342(7) Å, b = 13.5131(7) Å and c = 13.7025(7) Å. The iron center resides in distorted octahedral geometry coordinated to four equatorial imidazole groups and two axial triflate oxygens groups. The complex is high spin between 20 K and 300 K as indicated by variable field variable temperature magnetic measurements. A fit of the magnetic data yielded g = 2.24 and D = -0.80 cm-1. A large HOMO-LUMO gap energy (3.89 eV) exists for 1 indicating high stability. Addition of H2O2 or t BuOOH to 1 results in formation of an oxygenated intermediate which upon decomposition results in oxidation of the trityl substituent on the imidazole ligand.

Assembly of a mononuclear ferrous site using a bulky aldehyde-imidazole ligand

A new iron(II) complex has been prepared and characterized. [Fe(TrImA)2(OTf)2] (1, TrImA = 1-Tritylimidazole-4-carboxaldehyde). The solid state structure of 1 has been determined by X-ray crystallography. Compound 1 crystallizes in monoclinic space group P21/c, with a = 10.8323(18) Å, b = 8.1606(13) Å and c = 24.818(4) Å. The iron center is coordinated to two imidazole groups, two pendant aldehyde-derived carbonyl oxygens and two triflate oxygens. The complex is high spin between 300 and 20 K as indicated by variable field variable temperature magnetic measurements. A fit of the magnetic data yielded g = 2.17 and D = 4.05 cm-1. A large HOMO-LUMO gap energy (4.49 eV) exists for 1 indicating high stability.

trans-Diaqua-bis-[5-carb-oxy-2-(3-pyrid-yl)-1H-imidazole-4-carboxyl-ato-κN,O]cobalt(II)

In the title complex, [Co(C₁₀H₆N₃O₄)₂(H₂O)₂], the Co^II atom is located on an inversion centre and displays a distorted octa­hedral coordination geometry defined by two N,O-bidentate ligands in the equatorial plane and two water mol­ecules in the axial positions. The conformation is stabilized by intra­molecular O—H⋯O hydrogen bonds. Inter­molecular N—H⋯O hydrogen bonds link the mol­ecules into chains, which are further connected by inter­molecular O—H⋯O and O—H⋯N hydrogen-bonding inter­actions, forming a two-dimensional supra­molecular network parallel to (110).

3-(4-Carb-oxy-5-carboxyl-ato-1H-imidazol-2-yl)pyridin-1-ium monohydrate

In the zwitterionic mol­ecule of the title compound, C₁₀H₇N₃O₄·H₂O, one carboxyl group is deprotonated and the pyridine N atom is protonated. The pyridinium and imidazole rings form a dihedral angle of 5.23 (1)°. An intramolecular O—H⋯O hydrogen bond occurs. In the crystal, inter­molecular N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds link the zwitterions and water mol­ecules into sheets parallel to (102).