A Novel µ1,1-Azido-, µ2-Alkoxo-, and µ2-Phenoxo-Bridged Tetranuclear Copper(II) Complex with a Quinquedentate Schiff-Base Ligand: Magneto-Structural and DFT Studies

2009 ◽  
Vol 62 (4) ◽  
pp. 366 ◽  
Author(s):  
Subhra Basak ◽  
Soma Sen ◽  
Georgina Rosair ◽  
Cédric Desplanches ◽  
Eugenio Garribba ◽  
...  
Keyword(s):  
Schiff Base ◽  
Schiff Base Ligand ◽  
Density Functional ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Variable Temperature ◽  
Density Functional Theory Calculations ◽  
Magnetic Interactions ◽  
Resonance Spectroscopy ◽  
Paramagnetic Resonance ◽  
Ft Ir

A novel tetranuclear copper(ii) complex [Cu4L2(μ1,1- N3)2]·CH3CN (1) has been synthesized using a symmetrical quinquedentate N2O3-donor Schiff-base ligand H3L (N,N′-(2-hydroxypropane-1,3-diyl)bis(2- hydroxyacetophenimine)) and characterized by elemental analysis, Fourier-transform (FT)-IR, UV-visible, electron paramagnetic resonance spectroscopy, and cyclic voltammetry. The X-ray single-crystal structure of 1 reveals three kinds of bridges among the four metal centres: one from the exogenous azido ligand and two from the phenoxo and alkoxo moieties of the Schiff base. The same structure highlights the remarkable versatility of copper(ii) to adopt an array of stereochemistries. Four unusual eight-membered metallacycles exist in 1. The μ1,1-azido, μ2-alkoxo, and μ2-phenoxo bridges among the four copper centres have facilitated interesting magnetic interactions that have been elucidated by variable-temperature magnetic susceptibility measurements and backed up by density functional theory calculations. Detailed analyses have shown that the antiferromagnetic effect through the alkoxo-bridged CuII centres combined with the ferromagnetic interaction through the azido-bridged metal centres results in an S = 0 ground state.

scholarly journals The Structures, Spectroscopic Properties, and Photodynamic Reactions of Three [RuCl(QN)NO]−Complexes (HQN = 8-Hydroxyquinoline and Its Derivatives) as Potential NO-Donating Drugs

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Leilei Xie ◽  
Lifang Liu ◽  
Wenming Wang ◽  
Zhiou Ma ◽  
Liqun Xu ◽  
...  
Keyword(s):  
Density Functional ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Energy Levels ◽  
Spectroscopic Properties ◽  
Resonance Spectroscopy ◽  
Electronic Effects ◽  
Paramagnetic Resonance ◽  
Time Resolved ◽  
Potential Applications ◽  
Electron Paramagnetic

The structures and spectral properties of three ruthenium complexes with 8-hydroxyquinoline (Hhqn) and their derivatives 2-methyl-8-quinolinoline (H2mqn) and 2-chloro-8-quiolinoline (H2cqn) as ligands (QN = hqn, 2mqn, or 2cqn) were calculated with density functional theory (DFT) at the B3LYP level. The UV-Vis and IR spectra of the three [RuCl(QN)NO]−complexes were theoretically assigned via DFT calculations. The calculated spectra reasonably correspond to the experimentally measured spectra. Photoinduced NO release was confirmed through spin trapping of the electron paramagnetic resonance spectroscopy (EPR), and the dynamic process of the NO dissociation upon photoirradiation was monitored using time-resolved infrared (IR) spectroscopy. Moreover, the energy levels and related components of frontier orbitals were further analyzed to understand the electronic effects of the substituent groups at the 2nd position of the ligands on their photochemical reactivity. This study provides the basis for the design of NO donors with potential applications in photodynamic therapy.

scholarly journals Synthesis, spectroscopic characterization, DFT, oxygen binding, antioxidant activity on Fe(III), Co(II) and Ni(II) complexes with a tetradentate ONNO donor Schiff base ligand

2021 ◽  
pp. 37-37
Author(s):  
Satyendra Shukla ◽  
Pratiksha Gaur ◽  
Mohan Raidas ◽  
Sanjay Bagri
Keyword(s):  
Antioxidant Activity ◽  
Schiff Base ◽  
Schiff Base Ligand ◽  
Density Functional ◽  
Radical Scavenging ◽  
Spectroscopic Characterization ◽  
Binding Activity ◽  
Oxygen Binding ◽  
Ft Ir ◽  
Analytical Tools

The Schiff base ligand, namely (7E)-N-benzylidene-2-styrylbenzena-mine1,2-diamine-2,4-dihydroxy-phenol, (L), was synthesized from condensation of 2,4-dihydroxybenzaldehyde with o-phenylenediamine. The reaction of the ligand with Fe(III), Co(II) and Ni(II) salts in a 1: 1 ratio yielded three complexes 1-3. Different analytical tools like elemental analysis, ESI-mass spectra, FT-IR, conductivity, electronic spectra, magnetic susceptibility, NMR and EPR mea-surements are used to elucidate the structure of the ligand and complexes. Density Functional Theory (DFT) calculation at the B3LYP/3-211G++/LANL2DZ level of the theory has been carried out to optimize the geometry of the ligand and complexes. The tetradentate ligand has coordinated to metals through ONNO donors affording octahedral geometry. Complexes were studied for their oxygen-binding activity and free radical scavenging activities. Complex 1 and 2, which contain Fe(IIl) and Co(II), displayed reversible oxygen binding activity. On the other hand, complex 3 fails to show oxygen binding. The order of antioxidant activity is 3 > 1 > 2 > L.

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