scholarly journals Efficient Catalytic Reduction of 4-Nitrophenol Using Copper(II) Complexes with N,O-Chelating Schiff Base Ligands

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 5876
Author(s):  
Hassan Wafi Garba ◽  
Muhammad Sabiu Abdullahi ◽  
Mohamad Shazwan Shah Jamil ◽  
Nor Azam Endot
Keyword(s):  
Schiff Base ◽  
Catalytic Activity ◽  
Catalytic Reduction ◽  
Schiff Base Ligands ◽  
Paramagnetic Resonance ◽  
Nitrophenol Reduction ◽  
Ft Ir ◽  
Uv Visible ◽  
Electron Paramagnetic ◽  
Excellent Reproducibility

The reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride was used as a model to test the catalytic activity of copper(II) complexes containing N,O-chelating Schiff base ligands. In this study, a series of copper(II) complexes containing respective Schiff base ligands, N′-salicylidene-2-aminophenol (1), N′-salicylidene-2-aminothiazole (2), and N,N′-bis(salicylidene)-o-phenylenediamine (3), were synthesized and characterized by elemental analysis, Fourier transform infrared (FT-IR), and UV-Visible (UV-Vis) and electron paramagnetic resonance (EPR) spectroscopies. The results from the 4-nitrophenol reduction showed that 3 has the highest catalytic activities with 97.5% conversion, followed by 2 and 1 with 95.2% and 90.8% conversions, respectively. The optimization of the catalyst amount revealed that 1.0 mol% of the catalyst was the most optimized amount with the highest conversion compared to the other doses, 0.5 mol% and 1.5 mol%. Recyclability and reproducibility tests confirmed that all three complexes were active, efficient, and possess excellent reproducibility with consistent catalytic performances and could be used again without a major decrease in the catalytic activity.

Heterometallic CoIII4FeIII2 Schiff Base Complex: Structure, Electron Paramagnetic Resonance, and Alkane Oxidation Catalytic Activity

2012 ◽  
Vol 51 (16) ◽  
pp. 9110-9122 ◽  
Author(s):  
Dmytro S. Nesterov ◽  
Eduard N. Chygorin ◽  
Volodymyr N. Kokozay ◽  
Volodymyr V. Bon ◽  
Roman Boča ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Schiff Base ◽  
Catalytic Activity ◽  
Complex Structure ◽  
Schiff Base Complex ◽  
Alkane Oxidation ◽  
Paramagnetic Resonance ◽  
Base Complex ◽  
Electron Paramagnetic

Structural Variation and Magneto-Structural Correlation in Two New Dinuclear Bis(µ2-Phenoxo)-Bridged CuII Schiff-Base Complexes: Catalytic Potential for the Peroxidative Oxidation of Cycloalkanes

2010 ◽  
Vol 63 (3) ◽  
pp. 479 ◽  
Author(s):  
Subhra Basak ◽  
Soma Sen ◽  
Partha Roy ◽  
Carlos J. Gómez-García ◽  
David L. Hughes ◽  
...  
Keyword(s):  
Schiff Base ◽  
Exchange Interactions ◽  
Coupling Constants ◽  
Schiff Base Complexes ◽  
Schiff Base Ligands ◽  
Paramagnetic Resonance ◽  
Catalytic Potential ◽  
Elemental Analyses ◽  
Distorted Trigonal Bipyramid ◽  
Electron Paramagnetic

Two new dinuclear bis(μ2-phenoxo)-bridged copper(ii) complexes [Cu(NCS)L1]2 (1) and [Cu(NCS)L2]2 (2) have been synthesized using two tridentate NNO-donor Schiff-base ligands, L1H (Me2N(CH2)3N=CHC6H3(OMe)(OH)) and L2H (Me2N(CH2)3N=C(CH3)C6H4(OH)), respectively. They have been characterized by elemental analyses, IR, UV-visible, and electron paramagnetic resonance (EPR) spectroscopy, cyclic voltammetry, and magnetic susceptibility measurements. X-Ray single-crystal structures reveal a central Cu2O2 core in each complex with an isothiocyanate ligand coordinated terminally to each metal centre. The coordination environments around the CuII ions in 1 and 2 are a distorted trigonal bipyramid and a quasi-regular square pyramid, respectively, with significant differences in the Cu–O–Cu bridging angles (100.22(5)° for 1 and 95.64(7)° for 2). Although both CuII dimers present intradimer antiferromagnetic exchange interactions, the magnitudes of the coupling constants in 1 and 2 (J = –119(1) and –0.361(3) cm–1, respectively) are quite different as a result of the different coordination geometries and Cu–O–Cu bridging angles. Both complexes act as promising catalysts or catalyst precursors for the efficient peroxidative oxidation of cycloalkanes (cyclohexane and cycloheptane) to the corresponding cyclic alcohols and ketones, with maximum overall yields of 53% and 56% for 1 and 2, respectively.

scholarly journals Electrospun Nanosystems Based on PHBV and ZnO for Ecological Food Packaging

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2123
Author(s):  
Maria Râpă ◽  
Maria Stefan ◽  
Paula Popa ◽  
Dana Toloman ◽  
Cristian Leostean ◽  
...  
Keyword(s):  
Food Packaging ◽  
Spin Trapping ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
Hno3 Solution ◽  
X Ray ◽  
Trapping Method ◽  
Ft Ir ◽  
Doped Zno ◽  
Electron Paramagnetic

The electrospun nanosystems containing poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and 1 wt% Fe doped ZnO nanoparticles (NPs) (with the content of dopant in the range of 0–1 wt% Fe) deposited onto polylactic acid (PLA) film were prepared for food packaging application. They were investigated by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), antimicrobial analysis, and X-ray photoelectron spectrometry (XPS) techniques. Migration studies conducted in acetic acid 3% (wt/wt) and ethanol 10% (v/v) food simulants as well as by the use of treated ashes with 3% HNO3 solution reveal that the migration of Zn and Fe falls into the specific limits imposed by the legislation in force. Results indicated that the PLA/PHBV/ZnO:Fex electrospun nanosystems exhibit excellent antibacterial activity against the Pseudomonas aeruginosa (ATCC-27853) due to the generation of a larger amount of perhydroxyl (˙OOH) radicals as assessed using electron paramagnetic resonance (EPR) spectroscopy coupled with a spin trapping method.

Synthesis, Structure and Fluorescence Properties of a Trinuclear Zn(II) Complex with N,N,O-donor Schiff Base Ligands and Bridging Acetates

2009 ◽  
Vol 64 (4) ◽  
pp. 403-408 ◽  
Author(s):  
Shyamapada Shit ◽  
Joy Chakraborty ◽  
Brajagopal Samanta ◽  
Georgina M. Rosair ◽  
Samiran Mitra
Keyword(s):  
Schiff Base ◽  
Schiff Base Ligand ◽  
Fluorescence Properties ◽  
Schiff Base Ligands ◽  
Thermal Methods ◽  
Metal Centers ◽  
X Ray ◽  
Octahedral Environment ◽  
Distorted Octahedral ◽  
Ft Ir

A new centrosymmetric trinuclear Zn(II) complex [Zn3L2(CH3COO)4] (1) has been synthesized by the reaction of Zn(CH3COO)2 · 2H2O with a tridentate N,N,O-donor Schiff base ligand HL [C5H4NC(CH3)=NC6H4(OH)] and systematically characterized by elemental analysis, FT-IR, UV/Vis and thermal methods. Single crystal X-ray structure analysis reveals that three Zn(II) centers are in two different coordination environments. Two terminal Zn(II) centers adopt a distorted squarepyramidal geometry leaving the central Zn(II) in a distorted octahedral environment. Two adjacent metal centers are connected through single μ2-phenolato as well as double μ-acetato-O,O´ syn-syn bridges. Fluorescence properties of the complex as compared to the ligand indicate that the former can serve as a potential photoactive material.

scholarly journals Antimicrobial and Antioxidant Activities of Diorganotin(IV) Complexes Synthesized from 1,2,4-Triazole Derivatives

2020 ◽  
Vol 32 (10) ◽  
pp. 2553-2558
Author(s):  
Jyoti Yadav ◽  
Jai Devi
Keyword(s):  
Schiff Base ◽  
Antioxidant Activities ◽  
Azomethine Nitrogen ◽  
Spectroscopic Techniques ◽  
Schiff Base Ligands ◽  
Alkyl Aryl ◽  
Aryl Group ◽  
Ft Ir ◽  
Tin Metal

Novel diorganotin(IV) complexes were synthesized from 1,2,4-triazole Schiff base ligands which were synthesized by reaction between the 4-amino-5-phenyl-1,2,4-triazole-3-thiol and salicyaldehyde derivatives. The bonding and geometry of the diorganotin(IV) complexes were evaluated by using different spectroscopic techniques such as FT-IR, mass, 1H, 13C & 119Sn NMR. The different spectroscopic techniques revealed the tridentate (ONS) mode of chelation of Schiff base ligands and pentacoordinated environment around the central tin metal which was satisfied with azomethine nitrogen, phenolic oxygen, thiolic sulfur and metal-carbon bond of alkyl/aryl group. The Schiff base ligands and their organotin(IV) complexes were tested for their in vitro antimicrobial and antioxidant activities to examine the biological outline of complexes in comparison to standard drugs. The results of activities data revealed that diorganotin(IV) complexes are more active than Schiff base ligands and some diorganotin(IV) complexes are even more active than the standard drugs. In all the synthesized complexes, compound 9 (Bu2SnL2) and 10 (Ph2SnL2) were most potent and can be used in future clinical trials.

A facile biomimetic catalytic activity through hydrogen atom abstraction by the secondary coordination sphere in manganese(iii) complexes

2020 ◽  
Vol 49 (40) ◽  
pp. 14216-14230
Author(s):  
Narayan Ch. Jana ◽  
Paula Brandão ◽  
Antonio Frontera ◽  
Anangamohan Panja
Keyword(s):  
Schiff Base ◽  
Catalytic Activity ◽  
Hydrogen Atom ◽  
Coordination Sphere ◽  
Hydrogen Atom Abstraction ◽  
Schiff Base Ligands ◽  
Secondary Coordination Sphere ◽  
Catalytic Reactivity ◽  
Hydrogen Bonded

Four hydrogen bonded supramolecular manganese(iii) complexes with N3O donor Schiff base ligands and a facile biomimetic catalytic reactivity through hydrogen atom abstraction by the secondary coordination sphere have been reported.

Synthesis, structure, and catalytic activity of organolanthanide complexes with chiral biaryl Schiff-base ligands

2014 ◽  
Vol 758 ◽  
pp. 65-72 ◽  
Author(s):  
Wenshan Ren ◽  
Liang Chen ◽  
Ning Zhao ◽  
Qiuwen Wang ◽  
Guohua Hou ◽  
...  
Keyword(s):  
Schiff Base ◽  
Catalytic Activity ◽  
Schiff Base Ligands

A spectroscopic study of the reaction of gold atoms with CO in a rotating cryostat: formation of a variety of gold carbonyls

1989 ◽  
Vol 67 (4) ◽  
pp. 655-661 ◽  
Author(s):  
J. H. B. Chenier ◽  
J. A. Howard ◽  
H. A. Joly ◽  
B. Mile ◽  
M. Tomietto
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Optical Spectrum ◽  
Narrow Band ◽  
Visible Spectroscopy ◽  
Broad Absorption ◽  
Paramagnetic Resonance ◽  
Magnetic Parameters ◽  
Uv Visible ◽  
Electron Paramagnetic ◽  
Rotating Cryostat

Reaction of 197Au atoms with CO has been studied in inert hydrocarbon matrices in a rotating cryostat at 77 K by EPR, FTIR, and UV/visible spectroscopy. Au(CO)2 has been positively identified by FTIR spectroscopy and there is evidence for the formation of AuCO, a gold microcrystallite – CO complex and, upon annealing, Au2(CO)4. Electron paramagnetic resonance spectra are consistent with the formation of Au(CO) (OC) with the magnetic parameters: a13 = 325 MHz, a17 = 44 MHz, and g = 2.0014 and a gold microcrystallite – CO complex with g = 2.014. An intense broad absorption in the optical spectrum at 525 nm is assigned to Au(CO)2 and a less intense narrow band at 320 nm is assigned to AunCO. There is no spectroscopic evidence for the formation of Au(CO)3 in hydrocarbon matrices. Keywords: gold carbonyls, EPR, FTIR, UV/visible, matrix isolation.

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