Syntheses and EPR spectral studies of manganese(II) complexes derived from pyridine-2-carbaldehyde based N(4)-substituted thiosemicarbazones: Crystal structure of one complex

Rapheal, P.F.; Manoj, E.; Kurup, M.R. Prathapachandra

doi:10.1016/j.poly.2007.07.028

Cited by 51 publications

(23 citation statements)

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“…Mn-N pyridyl and Mn-N NCS bond lengths are similar to the ones reported for similar Mn(II)-thiocyanate monomeric complexes [35][36][37][38]. Mn-N pyridyl and Mn-N azomethine bond distances are also comparable to Mn(II) complexes of some thiosemicarbazones reported previously [39][40][41][42]. However these distances are slightly longer than those for the polymeric Mn(II)-azido complex using the same Schiff base [24].…”

Section: Crystal Structure Of Mn(papea) 2 (Ncs) 2 (3)supporting

confidence: 85%

Syntheses, EPR spectral studies and crystal structures of manganese(II) complexes of neutral N,N donor bidentate Schiff bases and azide/thiocyanate as coligand

et al. 2010

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a b s t r a c tFour manganese(II) complexes Mn 2 (paa) 2 (N 3 ) 4 (1), [Mn(paa) / 2 H 2 O (4) of three neutral N,N donor bidentate Schiff bases were synthesized and physico-chemically characterized by means of partial elemental analyses, electronic, infrared and EPR spectral studies. Compounds 3 and 4 were obtained as single crystals suitable for X-ray diffraction. Compound 4 recrystallized as Mn(dpka) 2 (NCS) 2 . Both the compounds crystallized in the monoclinic space groups P2 1 for 3 and C2/c for 4. Manganese(II) is found to be in a distorted octahedral geometry in both the monomeric complexes with thiocyanate anion as a terminal ligand coordinating through the nitrogen atom. EPR spectra in DMF solutions at 77 K show hyperfine sextets with low intensity forbidden lines lying between each of the two main hyperfine lines and the zero field splitting parameters (D and E) were calculated.Ó 2010 Elsevier Ltd. All rights reserved. IntroductionManganese complexes play important roles ranging from bioinorganic chemistry to solid-state physics. There has been considerable interest in synthesizing biomimetic complexes that can act as manganese containing enzymes such as superoxide dismutase (SOD) [1]. Interest in manganese complexes of varying nuclearities continues to be stimulated by the presence of manganese at the active sites of biological systems such as photosystem II in green plants, ribonucleotide reductase, superoxide dismutase, and the Mn catalases [2-9], the variability in magnetic behavior of polynuclear manganese clusters, which for some systems has been exploited in the development of information storage devices [10][11][12] and the use of such complexes as catalysts for bleaching and organic synthesis [13][14][15].In manganese biosystems, the azide ion is known to inhibit the superoxide dismutation in mononuclear superoxide dismutases via binding to the metal at the active site in both the Mn(II) and Mn(III) oxidation states [16]. The function of dinuclear active sites in Mn catalases, which catalyze the conversion of toxic peroxide to oxygen and water in certain bacteria, is also dramatically inhibited by azide [17][18][19][20][21][22].Gao et al. reports the structure and magnetism of Mn(II) one dimensional coordination polymers built from azide bridges and Schiff base obtained by the condensation of pyridine-2-carbaldehyde with aniline and its derivatives [23]. The complexes synthesized contain alternating end-on and end-to-end azide bridges, which mediate alternating ferromagnetic and antiferromagnetic exchange interactions, respectively. Wen and coworkers prepared one dimensional chiral coordination polymers of manganese(II) using azide and a Schiff base (obtained from pyridine-2-carbaldehyde and 1-phenylethyl amine) as the auxiliary ligand [24]. In these complexes, there is weak antiferromagnetic coupling between Mn(II) ions. The use of di-2-pyridyl ketone in conjugation with dicyanamide and azide gave cubane and defective doublecubane clusters of Mn(II) respectively, both of which are found to b...

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Section: Crystal Structure Of Mn(papea) 2 (Ncs) 2 (3)supporting

confidence: 85%

Syntheses, EPR spectral studies and crystal structures of manganese(II) complexes of neutral N,N donor bidentate Schiff bases and azide/thiocyanate as coligand

et al. 2010

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“…The EPR spectrum of the Mn(II) complex shows one broad isotropic signal with g value of 2.00 (see Table 5). Magnetic moment values of Cu(II) and Mn(II) complexes suggest that there are paramagnetic with µ effect values of 1.7 and 4.8 B.M with one and five unpaired electrons, respectively (see Table 4 and Table 5) [9,27,28,29,30,31].…”

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confidence: 99%

Full Structural Characterization of Homoleptic Complexes of Diacetylcurcumin with Mg, Zn, Cu, and Mn: Cisplatin-level Cytotoxicity in Vitro with Minimal Acute Toxicity in Vivo

et al. 2019

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At the present time, scientists place a great deal of effort worldwide trying to improve the therapeutic potential of metal complexes of curcumin and curcuminoids. Herein, the synthesis of four homoleptic metal complexes with diacetylcurcumin (DAC), using a ligand designed to prevent the interaction of phenolic groups, rendering metal complexes through the β-diketone functionality, is reported. Due to their physiological relevance, we used bivalent magnesium, zinc, copper, and manganese for complexation with DAC. The resulting products were characterized by ultraviolet-visible (UV-Vis), fluorescence spectroscopy, infrared spectroscopy (IR), liquid and solid-state nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), magnetic moment, mass spectrometry (MS), single crystal, and powder X-ray diffraction (SCXRD and PXRD). Crystallization was achieved in dimethylsulfoxide (DMSO) or N,N-dimethylformamide (DMF) as triclinic systems with space group P-1, showing the metal bound to the β-diketone function, while the 1H-NMR confirmed the preference of the enolic form of the ligand. Single crystal data demonstrated a 1:2 metal:ligand ratio. The inhibition of lipid peroxidation was evaluated using the thiobarbituric acid reactive substance assay (TBARS). All four metal complexes (Mg, Zn, Cu, and Mn) exhibited good antioxidant effect (IC50 = 2.03 ± 0.27, 1.58 ± 0.07, 1.58 ± 0.15 and 1.24 ± 0.10 μM respectively) compared with butylated hydroxytoluene (BHT) and α-tocopherol. The cytotoxic activity in human cancer cell lines against colon adenocarcinoma (HCT-15), mammary adenocarcinoma (MCF-7), and lung adenocarcinoma (SKLU-1) was found comparable ((DAC)2Mg), or ca. 2-fold higher ((DAC)2Zn) than cisplatin. The acute toxicity assays indicate class 5 toxicity, according to the Organization for Economic Co-operation and Development (OECD) guidelines at doses of 3 g/kg for all complexes. No mortality or changes in the behavior of animals in any of the treated groups was observed. A therapeutic potential can be envisaged from the relevant cytotoxic activity upon human cancer cell lines in vitro and the undetected in vivo acute toxicity of these compounds.

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“…The out-of-plane bending modes of vibrations of the free ligands at 622 cm À1 are found to be shifted to higher energies in the spectra of complexes indicating the coordination via pyridine nitrogen [30]. Further, the intense band observed in the region 945-980 cm À1 in all the complexes corresponds to the terminal V@O stretching.…”

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confidence: 85%

Chemistry of molecular and supramolecular structures of vanadium(IV) and dioxygen-bridged V(V) complexes incorporating tridentate hydrazone ligands

Mangalam

Sivakumar

Sheeja

et al. 2009

Inorganica Chimica Acta

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Syntheses and EPR spectral studies of manganese(II) complexes derived from pyridine-2-carbaldehyde based N(4)-substituted thiosemicarbazones: Crystal structure of one complex

Cited by 51 publications

References 15 publications

Syntheses, EPR spectral studies and crystal structures of manganese(II) complexes of neutral N,N donor bidentate Schiff bases and azide/thiocyanate as coligand

Syntheses, EPR spectral studies and crystal structures of manganese(II) complexes of neutral N,N donor bidentate Schiff bases and azide/thiocyanate as coligand

Full Structural Characterization of Homoleptic Complexes of Diacetylcurcumin with Mg, Zn, Cu, and Mn: Cisplatin-level Cytotoxicity in Vitro with Minimal Acute Toxicity in Vivo

Chemistry of molecular and supramolecular structures of vanadium(IV) and dioxygen-bridged V(V) complexes incorporating tridentate hydrazone ligands

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