Search results for "Schiff bases"
showing 10 items of 32 documents
Rare Example of μ-Nitrito-1κ2O,O′:2κO Coordinating Mode in Copper(II) Nitrite Complexes with Monoanionic Tridentate Schiff Base Ligands: Structure, M…
2008
Three new copper(II) complexes, [CuL(1)(NO(2))](n) (1), [CuL(2)(NO(2))] (2), and [CuL(3)(NO(2))] (3), with three similar tridentate Schiff base ligands [HL(1) = 6-amino-3-methyl-1-phenyl-4-azahept-2-en-1-one, HL(2) = 6-amino-3-methyl-1-phenyl-4-azahex-2-en-1-one, and HL(3) = 6-diethylamino-3-methyl-1-phenyl-4-azahex-2-en-1-one] have been synthesized and characterized structurally and magnetically. In all three complexes, the tridentate Schiff base ligand and one oxygen atom of the nitrite ion constitute the equatorial plane around Cu(II), whereas the second oxygen atom of the nitrite ligand coordinates to one of the axial positions. In 1, this axially coordinated oxygen atom of the nitrite …
Bioactive Co(II), Ni(II), and Cu(II) Complexes Containing a Tridentate Sulfathiazole-Based (ONN) Schiff Base
2021
New Co(II), Ni(II), and Cu(II) complexes were synthesized with the Schiff base ligand obtained by the condensation of sulfathiazole with salicylaldehyde. Their characterization was performed by elemental analysis, molar conductance, spectroscopic techniques (IR, diffuse reflectance and UV–Vis–NIR), magnetic moments, thermal analysis, and calorimetry (thermogravimetry/derivative thermogravimetry/differential scanning calorimetry), while their morphological and crystal systems were explained on the basis of powder X-ray diffraction results. The IR data indicated that the Schiff base ligand is tridentate coordinated to the metallic ion with two N atoms from azomethine group and thiazole ring a…
Targeting the mitochondrial pathway to induce apoptosis/necrosis through ROS by a newly developed Schiff’s base to overcome MDR in cancer
2011
Abstract Multidrug resistance (MDR) in cancer, a major obstacle to successful application of cancer chemotherapy, is often characterized by over-expression of multidrug resistance-related proteins such as MRP1, P-gp or elevated glutathione (GSH) level. Efflux of drugs by functional P-gp, MRP1 and elevated GSH level can confer resistance to apoptosis induced by a range of different stimuli. Therefore, it is necessary to develop new cell death inducers with relatively lower toxicity toward non-malignant cells that can overcome MDR by induction of apoptotic or non-apoptotic cell death pathways. Herein we report the synthesis and spectroscopic characterization of a GSH depleting, redox active S…
Antibacterial and antitumoral activities of new organotin(IV)-Schiff bases derivatives
2018
This preliminary report shows eight complexes of triorganotin(IV): Ph3SnOH and (CH3)3SnOH with four chelating imines on new synthesis. Of these ligands, two are salen-like (four coordination sites, two imidic, two phenoxidic) [1], one is a tetradentate pyrrole derivative [2] while the fourth, a vita- min B6 derivative, is pentadentate [3]. Ligands have been characterized by means of FT-IR, UV-Vis, Fluorescence, 1H- and 13C-NMR, LC-MS ESI triple quadrupole; complexes by means FT-IR, 1H- and 119Sn-NMR, LC-MS ESI, using the isotopic distribution pattern as a discriminant [4]. Geometry and nature of coordination complexes have been also evaluated using the 119Sn chemical shifts. Solid-state syn…
Ni(II) and Zn(II) Schiff Base complexes: B-DNA vs G4-DNA binding
2015
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…
Crystal structure ofS-octyl (E)-3-(4-methoxybenzylidene)dithiocarbazate
2015
As already observed in similar molecules, the dithiocarbazate group in the title compound, C17H26N2OS2, adopts anEEconfiguration with respect to the C=N bond of the benzylidene moiety. In the crystal, molecules are connected into inversion dimers by pairs of N—H...S hydrogen bonds. The dimers are linked by weak π–π interactions, with centroid-to-centroid distances of 3.723 (11) Å, forming chains parallel to [110].
Crystal structure of (E)-N-(3,4-dimethoxybenzylidene)morpholin-4-amine
2014
In the title compound, C13H18N2O3, the benzene ring makes a dihedral angle of 17.19 (11)° with the least-squares plane formed by the four C atoms of the morpholine ring, which adopts a chair conformation. In the crystal, C—H...N hydrogen bonds link the molecules into supramolecular chains running along a 21screw axis parallel to theb-axis direction. Weak C—H...π interactions are also observed.
A tetranuclear cubane-like nickel(II) complex with a tridentate salicylideneimine Schiff base ligand: tetrakis[μ3-4-methyl-N-(2-oxidophenyl)salicylid…
2016
The tetranuclear title complex, [Ni4(C14H11NO2)4(CH3OH)4]·0.8CH3OH, has a distorted cubane topology shaped by four Schiff base ligands. The cubane [Ni4(μ3-O4)] core is formedviathe O atoms from the Schiff base ligands. The octahedrally coordinated NiIIions occupy alternating vertices of the cube. Each NiIIion is coordinated by oneO,N,O′-tridentate dianionic ligand, two O atoms of oxidophenyl groups from adjacent ligands and the O atom of a coordinating methanol molecule. The cubane core is stabilizedviaan intramolecular O—H...O hydrogen bond between the hydroxy group of the coordinating methanol molecules and the phenolate O atom of the aldehyde Schiff base fragment. Additional stabilizatio…
Simple Rules for Complex Near-Glass-Transition Phenomena in Medium-Sized Schiff Bases
2022
Glass-forming ability is one of the most desired properties of organic compounds dedicated to optoelectronic applications. Therefore, finding general structure–property relationships and other rules governing vitrification and related near-glass-transition phenomena is a burning issue for numerous compound families, such as Schiff bases. Hence, we employ differential scanning calorimetry, broadband dielectric spectroscopy, X-ray diffraction and quantum density functional theory calculations to investigate near-glass-transition phenomena, as well as ambient- and high-pressure molecular dynamics for two structurally related Schiff bases belonging to the family of glycine imino esters. Firstly…