Search results for "schiff base"

Ni(II) and Zn(II) Schiff Base complexes: B-DNA vs G4-DNA binding

2015

Preferential azido bridging regulating the structural aspects in cobalt(III) and copper(II)–Schiff base complexes: Syntheses, magnetostructural corre…

2011

International audience; A tridentate NNO donor Schiff base ligand [(1Z,3E)-3-((pyridin-2-yl)methylimino)-1-phenylbut-1-en-1-ol = LH] in presence of azide ions coordinates with cobalt(II) and copper(II) ions giving rise to three new coordination complexes [Co2(L)2(μ1,1-N3)2(N3)2] (1), [Cu2(L)2(μ1,3-N3)]·ClO4 (2) and [(μ1,1-N3)2Cu5(μ-OL)2(μ1,1-N3)4(μ1,1,1-N3)2]n (3). The complexes have been characterized by elemental analysis, FT-IR, UV–Vis spectral studies, and single crystal X-ray diffraction studies. These complexes demonstrate that under different synthetic conditions the azide ions and the Schiff base ligand (LH) show different coordination modes with cobalt(II) and copper(II) ions, givi…

NaI/CuI–II heterometallic cages interconnected by unusual linear 2-coordinate OCN-Cu(I)-NCO links: synthesis, structural, magnetostructural correlati…

2009

A new Na(I)/Cu(I-II) heterometallic coordination complex [Cu(2)L(2)Na(NCO)(2)Cu](n) (1) with an unusual architecture has been synthesised. In 1 cyclic Na-O-Cu-O-Cu cages constructed by the tetradentate N(2)O(2) donor Schiff base ligand (H(2)L = N, N'-bis(2-hydroxyacetophenone) propylenediimine) are interconnected to each other by a rare singly end-to-end bridged OCN-Cu(I)-NCO link generating 1D chain. The complex has been characterised by elemental, spectral and structural analysis. The cyclic voltammogram of 1 has been compared with the analogous complexes. Cryomagnetic susceptibility studies indicate the copper(II) centers in the cyclic Na-O-Cu-O-Cu cages are antiferromagnetically coupled…

Thiophene based imino-pyridyl palladium(II) complexes : Synthesis, molecular structures and Heck coupling reactions

2017

Abstract The new compounds (5-methyl-2-thiophene-2-pyridyl(R))imine [R = methyl (L1); R = ethyl (L2)] and (5-bromo-2-thiophene-2-pyridyl(R)imine [R = methyl (L3); R = ethyl (L4)] were successfully synthesized via Schiff base condensation reaction and obtained in good yields. These potential ligands were reacted with [PdCl2(COD)] and [PdClMe(COD)] to give the corresponding complexes [PdCl2(L)] (L = L1-L4; 1–4) and [PdClMe(L)] (L = L1-L4; 5–8). All compounds were characterized by IR, 1H and 13C NMR spectroscopy, elemental analysis and mass spectrometry. The molecular structures of 1, 2, 6 and 8 were confirmed by X-ray crystallography. The complexes were evaluated as catalyst precursors for st…

A surface hopping algorithm for nonadiabatic minimum energy path calculations

2015

The article introduces a robust algorithm for the computation of minimum energy paths transiting along regions of near-to or degeneracy of adiabatic states. The method facilitates studies of excited state reactivity involving weakly avoided crossings and conical intersections. Based on the analysis of the change in the multiconfigurational wave function the algorithm takes the decision whether the optimization should continue following the same electronic state or switch to a different state. This algorithm helps to overcome convergence difficulties near degeneracies. The implementation in the MOLCAS quantum chemistry package is discussed. To demonstrate the utility of the proposed procedur…

NiII, and ZnII Schiff Base Complexes: Telomeric G-quadruplex Stabilizers

2014

Recently, NiII and ZnII metal complexes of the ligand Salpyrim have been synthesized and characterized. Their affinity for wild-type h-Telo G-quadruplex DNA and for calf thymus DNA was investigated by UV absorption spectroscopy, circular dichroism and viscometry. The data collectively suggest that both complexes bind effectively to G-quadruplexes by direct end-stacking, stabilizing the oligonucleotide secondary structure. The two complexes are also typical B-DNA intercalators. Remarkably, their binding constants, Kb, with the G4s structures are about 10 fold higher than those with B-DNA, highlighting the selectivity. Experiments to evaluate the biological activity of the two complexes again…

Solvent Modulated Assembly of Two Ni(II) Complexes: Syntheses, Structures and Magnetic Properties

2016

A dinuclear [Ni2(L)2(DMSO)2(MeOH)2] (1) and a tetra-nuclear [Ni4(L)4(DMF)2(H2O)2].DMF (2) Ni(II) complexes have been prepared by treating nickel nitrate hexahydrate with the Schiff base ligand H2L (H2L=(E)-2-(2-hydroxybenzyliden)amino-4-nitrophenol) in a one-pot reaction. Complex 1 was obtained after recrystallization of the precipitate from the reaction with a 1:1:1 mixture of DMSO/CH2Cl2/MeOH. In contrast, the tetrameric complex 2 was obtained after slow evaporation of the filtrate. Both complexes were characterized by analytical, thermogravimetric, optical and magnetic techniques. The solid state molecular structures of 1 and 2 were determined by single crystal X-ray crystallography. Com…

Studies on some antimony(III) complexes with tridentate schiff base ligands

1981

Abstract The antimony(III) complexes FSb(Sab), ClSb(Sab) and ClSb(Sat) containing dianonic, potentially tridentate Schiff-base ligands with ONO(Sab 2− ) and ONS(Sat 2− ) donor atoms have been prepared and characterized. The mass spectra of these derivatives are reported. The occurrence of chelation by the tridentate ligand is inferred from the infrared data. The antimony-121 Mossbauer parameters at 4.2 K are reported. The magnitudes and the positive sign of eQV zz suggest a consistent p-character of the antimony lone-pair orbital. Observed differencies in the isomer shift and eQV zz values are discussed on the basis of the likely distribution of electron density around antimony.

Supramolecular Structure and Antimicrobial Activity of Ni(II) Complexes with s-Triazine/Hydrazine Type Ligand

2023

The two complexes, [Ni(DPPT)2](NO3)2*1.5H2O (1) and [Ni(DPPT)(NO3)Cl].EtOH (2), were synthesized using the self-assembly of (E)-2,4-di(piperidin-1-yl)-6-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)-1,3,5-triazine (DPPT) with Ni(NO3)2*6H2O in the absence and presence of NiCl2*6H2O, respectively. In both cases, the neutral tridentate DPPT ligand is found coordinated to the Ni(II) via three N-atoms from the hydrazone, pyridine and s-triazine rings. Hence, the homoleptic complex 1 has a NiN6 hexa-coordination environment while two NO3− are counter anions in addition to one-and-a-half crystallized hydration water molecules are found acting as an outer sphere. The heteroleptic complex 2 has a NiN3O…

Insertion of FeII complexes with Schiff base ligands derived from imidazole or pyridine into 3D bimetallic oxalate-based ferromagnets

2013

Abstract The syntheses, structures and magnetic properties of the compounds [FeII(imid2-trien)][MnII(CH3OH)CrIII(ox)3]2·(CH3OH)4(CH3CN)(H2O) (1), [FeII(tren(6-Me-py)3)][MnIICrIII(ox)3][MnII(CH3OH)0.58(H2O)0.42CrIII(ox)3]·(CH3OH)2(CH3CN)0.5(H2O)0.42 (2) and [FeII(tren(imid)3)]2[Mn2.5(CH3OH)3Cr3(ox)9]·(CH3OH)4.75·(H2O)4.25 (3) are reported. They are prepared by the insertion of FeII-Schiff base complexes derived from imidazole and pyridine into bimetallic oxalate networks. Different types of 3D oxalate networks are obtained for each templating cation. Thus, [FeII(imid2-trien)]2+ and [FeII(tren(6-Me-py)3)]2+ give rise to unusual 3D achiral bimetallic oxalate networks with heptacoordinated MnII…