A binuclear chloride bridged Cu(II) and a mononuclear Ni(II) complex: Synthesis, crystal structure, photo catalytic and biological studies

In Vitro Insight on Antifungal-Specific Potentiality of Ni(II) Complex against Colletotrichum siamense and Fusarium equisetum Phytopathogens

In an initiation to investigate a prospective bioactive compound, a mononuclear Ni(II) complex with N, N, and O donor Schiff base ligand was synthesized and characterized in the present study through FTIR, ESI-mass, and X-ray crystallographic diffraction studies. A slightly distorted octahedral geometry has been obtained for the Ni(II) complex from X-ray crystallographic diffraction studies. In vitro comprehensive biological studies show the antifungal specific efficiency of the complex against Colletotrichum siamense (AP1) and Fusarium equisetum (F.E.) pathogens, which are responsible for anthracnose and wilt disease, respectively, but no inhibitory effect on both Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration (MIC) for these pathogens was observed to be 0.25 and 0.5 mM, respectively. The experiment also reveals that significant damage of mycelia and enlarged, misshaped damaged spores are noticed in comparison to hexaconazole, used as a positive control under a light microscope post 48 h treatment of AP1 and F.E. with the MIC of the complex. The binding interaction studies of the complex with DNA and BSA performed through a variety of spectroscopic techniques demonstrate a strong binding behavior of the complex for both the binding systems. The observed negative ΔH° and ΔS° values for DNA reveal the existence of hydrogen-bonding/van der Waals interactions for DNA which was also exemplified from the molecular docking and self-assembly studies of the complex. The positive ΔH° and ΔS° values for BSA demonstrate the hydrophobic interactions of the complex with BSA. However, cytotoxicity studies against the MDA-MB-231 breast cancer cell line did not demonstrate any significant potentiality of the complex as an anticancer agent. All the bio-experimental studies provide clear evidence that the synthesized Ni(II) complex exhibits potential antifungal activity and could be used as a therapeutic fungicide agent in comparison to hexaconazole in agricultural practices.

Reductive Coupling of Nitroarenes and HCHO for General Synthesis of Functional Ethane-1,2-diamines by a Cobalt Single-Atom Catalyst

Despite the extensive applications, selective and diverse access to N,N'-diarylethane-1,2-diamines remains, to date, a challenge. Here, by developing a bifunctional cobalt single-atom catalyst (CoSA-N/NC), we present a general method for direct synthesis of such compounds via selective reductive coupling of cheap and abundant nitroarenes and formaldehyde, featuring good substrate and functionality compatibility, an easily accessible base metal catalyst with excellent reusability, and high step and atom efficiency. Mechanistic studies reveal that the N-anchored cobalt single atoms (CoN4) serve as the catalytically active sites for the reduction processes, the N-doped carbon support enriches the HCHO to timely trap the in situ formed hydroxyamines and affords the requisite nitrones under weak alkaline conditions, and the subsequent inverse electron demand 1,3-dipolar cycloaddition of the nitrones and imines followed by hydrodeoxygenation of the cycloadducts furnishes the products. In this work, the concept of catalyst-controlled nitroarene reduction to in situ create specific building blocks is anticipated to develop more useful chemical transformations.

Nickel Complexes Bearing ONS Chelating Ligands: A Promising Contender for In Vitro Cytotoxicity Effects on Human Pancreatic Cancer MIA-PaCa-2 Cells

The highly chronic human pancreatic cancer cell is one of the major reasons for cancerous death. Nickel complexes are recently gaining interest in anticancer activities on different types of cancer cells. Hence, in this study, we synthesized and characterized a series of ONS donor ligands [2-HO-C₆H₄-CH═N-(C₆H₄)-SH] (L1), [2-OH-3-OMe-C₆H₃-CH═N-(C₆H₄)-SH] (L2), [2-OH-3,5-(C(Me)₃)₂-C₆H₂-CH═N-(C₆H₄)-SH] (L3), [2-OH-C₆H₄-CH═N-(C₆H₄)-SMe] (L4), [2-OH-3-OMe-C₆H₃-CH═N-(C₆H₄)-SMe] (L5), [2-OH-3,5-(C(Me)₃)₂-C₆H₂-CH═N-(C₆H₄)-SMe] (L6) and their Ni(II) metal complexes [(MeOH)Ni(L1-L1-4H)] (1), [(MeOH)Ni(L2-L2-4H)] (2), [(MeOH)Ni(L3-L3-4H)] (3), [(L4-H)₂Ni] (4), [(L5-H)₂Ni] (5), and [(L6-H)₂Ni] (6). The single-crystal X-ray diffraction data of complexes 1 and 4 were collected to elucidate the geometry around the metal center. The anticancer activity of complexes 1-6 was investigated on human pancreatic cancer cell line MIA-PaCa-2, which revealed that complexes 4 and 6 were the most significantly effective in decreasing the cell viability of cancer cells at the lowest dose. The structure parameters obtained from single-crystal X-ray diffraction data are found to be in good agreement with the data from density functional theory and Hirshfeld surface analysis for complex 1.

Synthesis and characterization of the new ligand, 1,2,4-triazino[5,6-b]indol-3-ylimino methyl naphthalene-2-ol and its Ni(II) and Cu(II) complexes: comparative studies of their in vitro DNA and HSA Binding

A new ligand 1,2,4-triazino[5,6-b]indol-3-ylimino methyl naphthalene-2-ol (HL) was derived from 5H-[1,2,4]triazino[5,6-b]indol-3-amine and 2-hydroxy-1-naphthaldehyde. The metal complexes of the type [Ni(L)(Bipy)]1/2SO₄ (1), [Cu(L)(Bipy)(H₂O)₂]1/2SO₄ (2), [Ni(L)(Phen)]1/2SO₄ (3) and [Cu(L)(Phen)(H₂O)₂]1/2SO₄ (4) were synthesized. The ligand (HL) and complexes 1-4 were thoroughly characterized by elemental analysis and spectroscopic methods (FT-IR, ToF-MS, ¹H NMR, ¹³C NMR), molar conductance and magnetic moment determination. The Ni(II) complexes 1 and 3 adopt the square planar geometry and Cu(II) complexes 2 and 4 acquire distorted octahedral arrangement. In vitro DNA binding behavior of ligand (HL) and metal complexes 1-4 was explored by fluorescence spectral and ethidium bromide studies. The outcomes reveal that the complexes interact with DNA via non-covalent groove binding and electrostatic interactions. The higher binding constant (K) values of 4.35 × 10⁴ and 9.12 × 10⁴ M^-1 for complexes 2 and 4 indicate stronger binding ability with DNA. Moreover, in vitro human serum albumin (HSA) binding experiment with HL and complexes 1-4 reveals conformational modulations in the Trp-214 microenvironments in the subdomain IIA pocket.

Synthesis, Structural Characterization of a New Ni(II) Complex and Its Catalytic Activity for Oxidation of Benzyl Alcohol

In ethanol-water (v:v = 1:1), a new Ni(II) complex, [Ni(L)2(H2O)2] (1) (HL = 6-phenylpyridine-2-carboxylic acid) was synthesized using 6-phenylpyridine-2-carboxylic acid, NaOH and Ni(CH3COO)2.4H2O. The structure of complex 1 has been determined by elemental analysis and single crystal X-ray diffraction. The single crystal analysis shows that complex 1 contains one Ni(II) ion, two L ligands and  two coordinated water molecules. In 1, the Ni(II) ion is six-coordinated to two O atoms and two N atoms from L ligands and two O atoms from coordinated water molecules, respectively, which form a distorted octahedral coordination geometry. The whole unit of complex 1 is interconnected to each other through intermolecular N−H•••O hydrogen bonds involving oxygen atom of coordinated water molecule and the oxygen atoms of  L ligand to form 1D molecular architecture. The catalytic activity of complex 1 for oxidation of benzyl alcohol with O2 was investigated. The complex 1 shows good catalytic performance for the oxidation of benzyl alcohol, the benzyl alcohol conversion, benzaldehyde selectivity, and benzaldehyde yield were 49.1%, 92.0%, and 45.2%, respectively, at 90 °C under 0.7 Mpa O2 for 2 h. Moreover, complex 1 could be recovered easily by centrifugation and used repetitively for at least four times. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).