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Concept: Schiff base

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Copper is an essential element in various metabolisms. The investigation was carried out to evaluate acute gastroprotective effects of the Copper (II) complex against ethanol-induced superficial hemorrhagic mucosal lesions in rats.

Concepts: Chemical element, Toxicology, Acute toxicity, Alchemy, Schiff base, Peter Slabakov, Hugo Schiff

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Isatin is an important compound from the biological aspect of view. It is an endogenous substance and moreover; various pharmacological activities have been reported for isatin and its derivatives. In-vitro cytotoxic effects of the prepared isatin Schiff bases toward HeLa, LS180 and Raji human cancer cell lines has been reported in our previous work. 3-(2-(4-nitrophenyl)hydrazono) indolin-2-one was found to be the most potent one among the studied compounds (IC(30) = 12.2 and 21.8 μM in HeLa and LS-180 cell lines, respectively). Obtained biological data could be well interpreted using docking binding energies toward vascular endothelial growth factor receptor (VEGFR-2); a key anticancer target being biologically investigated against various isatin derivatives. In the present work, quantum mechanical (QM) method including functional B3LYP in association with split valence basis set using polarization functions (Def2-SVP) was used to estimate individual ligand-residue interaction energies for the docked 3-(2-(4-nitrophenyl)hydrazono) indolin-2-one into VEGFR-2 active site. Results were further interpreted via calculated polarization effects induced by individual amino acids of the receptor active site. A fairly good correlation could be found between polarization effects and estimated binding energies (R(2) = 0.7227). Conformational analysis revealed that 3-(2-(4-nitrophenyl) hydrazono) indolin-2-one might not necessarily interact with the VEGFR-2 active site in its minimum energy conformation.

Concepts: Immune system, Cell, Energy, Cell biology, Chemical bond, Cell culture, Imine, Schiff base

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Metal (II) complexes derived from S-benzyl-N-(1-ferrocenyl-3-(4-methylbenzene)acrylketone) dithiocarbazate; HL(1), S-benzyl-N-(1-ferrocenyl-3-(4-chlorobenzene)acrylketone)dithiocarbazate; HL(2), all the compounds were characterized using various spectroscopic techniques. The molar conductance data revealed that the chelates were non-electrolytes. IR spectra showed that the Schiff bases were coordinated to the metal ions in a bidentate manner with N, S donor sites. The ligands and their metal complexes have been screened for in vitro antibacterial, antifungal properties. The result of these studies have revealed that zinc (II) complexes 6 and 13 of both the ligands and copper (II) complexes 9 of the HL(2) were observed to be the most active against all bacterial strains, antifungal activity was overall enhanced after complexation of the ligands.

Concepts: Spectroscopy, Ligand, Metal, Zinc, Copper, Coordination chemistry, Silver, Schiff base

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Eleven mononuclear copper(II), nickel(II), zinc(II) and cobalt(II) complexes of Schiff base ligands derived from 3,5-dibromosalicylaldehyde/3,5-dichlorosalicylaldehyde were synthesized and determined by single crystal X-ray analysis. The crystal structures of complexes 1, 2, 4, 5, 6, 8 and 11 present the square-planar coordination geometry at the metal center and complexes 7, 9 and 10 show the distorted tetrahedral geometry. While one copper center in 3 has a square-planar geometry, the other copper is slightly distorted square-planar. The inhibitory activities of all the obtained complexes were tested in vitro against jack bean urease. It was found that Schiff base copper(II) complexes 1, 3, 5, 8 and 11 showed strong urease inhibitory activities (IC(50) = 1.51-3.52 μM) compared with acetohydroxamic acid (IC(50) = 62.52 μM), which was a positive reference. Their structure-activity relationships were further discussed.

Concepts: Acid, Coordination complex, Ligand, Metal, Zinc, Coordination chemistry, Solid, Schiff base

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The condensation products of salicylaldehyde and different diamines constitute an important class of diiminic Schiff bases (DSBs). This class of compounds has been rediscovered as reducing as well as capping agents under UV irradiation. UV irradiation of alkaline DSB solutions in the presence of water-soluble copper salts has been employed to produce copper nanoparticles (CuNPs). Intriguing CuNP-stimulated fluorescence behavior of the solution has been observed. Depending upon the nature of the spacer in between two iminic bonds, fluorescence enhancement or quenching is observed. Such surprising fluorescence contrast has been ascribed to far-field radiation and lossy surface waves.

Concepts: Fluorescence, Ultraviolet, Electromagnetic radiation, Chemistry, Solubility, Solutions, Solution, Schiff base

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Novel chiral Schiff base ligands ®/(S)-2-amino-3-(((1-hydroxypropan-2-yl)imino)methyl)-4H-chromen-4-one (L(1) and L(2) ) derived from 2-amino-3-formylchromone and (R/S)-2-amino-1-propanol and their Cu(II)/Zn(II) complexes (, , , and ) were synthesized. The complexes were characterized by elemental analysis, infrared (IR), hydrogen ((1) H) and carbon ((13) C) nuclear magnetic resonance (NMR), electrospray ionization-mass spectra (ESI-MS), and molar conductance measurements. The DNA binding studies of the complexes with calf thymus were carried out by employing different biophysical methods and molecular docking studies that revealed that complexes and prefers the guanine-cytosine-rich region, whereas and prefers the adenine-thymine residues in the major groove of DNA. The relative trend in K(b) values followed the order       . This observation together with the findings of circular dichroic and fluorescence studies revealed maximal potential of ®-enantiomeric form of complexes to bind DNA. Furthermore, the absorption studies with mononucleotides were also monitored to examine the base-specific interactions of the complexes that revealed a higher propensity of Cu(II) complexes for guanosine-5'-monophosphate disodium salt, whereas Zn(II) complexes preferentially bind to thymidine-5'-monophosphate disodium salt. The cleavage activity of and with pBR322 plasmid DNA was examined by gel electrophoresis that revealed that they are good DNA cleavage agents; nevertheless, proved to show better DNA cleavage ability. Topoisomerase II inhibitory activity of complex revealed that the complex inhibits topoisomerase II catalytic activity at a very low concentration (25 μM). Furthermore, in vitro antitumor activity of complexes and were screened against human carcinoma cell lines of different histological origin. Chirality 24:977-986, 2012. © 2012 Wiley Periodicals, Inc.

Concepts: DNA, Molecular biology, Biology, Hydrogen, Nuclear magnetic resonance, Plasmid, Topoisomerase, Schiff base

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The compartmental Schiff base ligands N,N'-ethylenebis(3-hydroxysalicylidene) (H(4)L) and N,N'-propylenebis(3-hydroxysalicylidene) (H(4)L') have been employed in the synthesis of a cyclic tetranuclear Cu(ii) complex [Cu(4)(L')(2)(MeOH)(3)(H(2)O)]·[Cu(4)(L')(2)(MeOH)(3)] (), a novel octanuclear Cu(ii) complex [Cu(8)(L-L)(2)(H(2)O)(4)(μ(2)-H(2)O)]·3DMF·3H(2)O () and a hetero-octanuclear Cu(ii)-Fe(iii) complex [Cu(4)Fe(4)(L)(4)(H(2)O)(3)(μ(3)-O)(2)]·3DMF·3H(2)O (). During the formation of the Cu(8) complex (), a new bis-Schiff base ligand (L-L)(8-) forms via the ortho-para C-C coupling of two H(4)L ligands. The bicyclic complex () is comprised of two cyclic Cu(4) units that are similar to that of complex . In the Cu(4) unit, the alternate Cu(ii) ions are singly bridged by phenoxo groups. The three complexes display overall antiferromagnetic coupling, and the Cu(ii)-Cu(ii) magnetic coupling constant falls in the range -117.2 to -473.6 cm(-1) for complexes and corresponding to the bridging Cu-O(phenoxide)-Cu bond angles of 124.3-131.0°.

Concepts: Ammonia, Magnetism, Cyanide, Ligand, Lone pair, Schiff base

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Two novel bpy-bridged Co(II) Schiff base complexes have been synthesized by the hydro(solvo)thermal reactions of corresponding amino-acid-based Schiff bases, bpy and Co(NO(3))(2)·6H(2)O. The following formulae identify the two complexes: {[Co(napala)(bpy)(0.5)]·H(2)O}(n) () and [Co(napgly)(bpy)(0.5)](n) () [H(2)napala = N-(2-hydroxy-1-naphthylmethylidene)-d/l-alanine, H(2)napgly = N-(2-hydroxy-1-naphthylmethylidene)-glycine and bpy = 4,4'-bipyridine]. These two compounds have been characterized using single-crystal X-ray diffraction, infrared, powder X-ray diffraction, thermogravimetric analysis, optical spectra analysis, and magnetic measurement. Complex features an unprecedented threefold interpenetrated diamond network based on the fan-shaped Co(II)(4)(μ(2)-napala)(4) molecular square node and bpy linker, which represents the first example of 3D framework among the amino-acid-based Schiff base complexes with salicylaldehyde or its derivatives. In , adjacent Co(II) ions are bridged by μ(2)-napgly(2-) to form left- and right-handed [Co(II)(μ(2)-napgly)](n) helical chains. These two types of helical chains are sustained alternately by a symmetrical bpy co-ligand into a 2D grid-based layer. The solid-state fluorescence of complexes and are quenched almost completely compared with free mixed-ligands at room temperature. Moreover, magnetic studies show the dominant antiferromagnetic coupling between the Co(II) centers mediated by the syn-anti-COO(-)-bridges in both complexes.

Concepts: Electron, Diffraction, X-ray, Functional groups, Powder diffraction, Imine, Schiff base, Hugo Schiff

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Photochromic Schiff bases 5-diethylamino-2-[(4-diethylamino-benzylidene)-hydrazonomethyl]-phenol (DDBHP) and N,N'-bis(4-N,N-diethylaminosalisalidene) hydrazine (DEASH) with both the proton and charge transfer moieties have been synthesized, and their photophysical properties such as excited state intramolecular charge transfer (ICT) and proton transfer (ESIPT) processes have been reported on the basis of steady-state and time-resolved spectral measurement in various solvents. The ground-state six-membered intramolecular hydrogen bonding network at the proton transfer site accelerates the ESIPT process for these compounds. Both the compounds show large Stokes-shifted emission bands for proton transfer and charge transfer processes. The hydrogen bonding solvents play a crucial role in these photophysical processes. Excited-state dipole moment of DDBHP and DEASH calculated by the solvatochromic method supports the polar character of the charge transfer excited state. Introduction of -NEt(2) groups to the reported salicylaldehyde azine (SAA) Schiff base results an increase in fluorescence lifetime from femtosecond to picosecond time scale for the proton transfer process.

Concepts: Electron, Oxygen, Hydrogen, Atom, Hydrogen bond, Imine, Schiff base, Hugo Schiff

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Three tetranuclear clusters [(TpMe,mt3)Fe(CN)3Mn(L)]2 (, L = 5-Clacphmen; , L = 5-Clsalen; , L = 5-MeOsalen; TpMe,mt3 = hydrotris(3-methyl-4,5-propylene-5-methylpyrazol-1-yl)borate) were prepared by assembling the fac-Fe tricyanide with the corresponding Mn Schiff bases. The assembled molecules are linked by cyanide and phenoxide bridges. Weak π-π contacts between molecules are evident in these clusters. Compounds exhibit slow relaxation of the magnetization. The phenoxide linkers mediate ferromagnetic coupling between the Mn centers, which is ascribed to the long axial Mn-O* length. The overall magnetic exchange coupling nature of the Fe-C[triple bond, length as m-dash]N-Mn route is accounted for by the important structural parameters of bridging pathways such as Mn-Ncyano length, Mn-Ncyano-Ccyano angle, and Ceq-FeMn-Neq (eq = equatorial) torsion angle.

Concepts: Magnetic field, Structure, Magnetism, Ferromagnetism, Cyanide, Ion, Chemical compound, Schiff base