Showing papers on "Schiff base published in 1973"
TL;DR: In this article, the Schiff base S-methyl-β-N-(2-hydroxyphenyl)methylendithiocarbazate, o -HO.
107 citations
TL;DR: Spectrophotometric titration studies at pH 8.0 imply that pyridoxal-P binds at the active site not only through a Schiff base but also through noncovalent, ionic interactions with the phosphate binding region, which implies that 1 lysine residue and 2 histidine residues are probably near the active sites of aspartate transcarbamylase.
79 citations
TL;DR: In this article, the authors investigated organotin(IV) complexes with quadri-and terdentate anionic Schiff base ligands using 119Sn Mossbauer and IR spectroscopies, and showed that the asymmetry parameter of the electric field gradient is close to unity, confirming a mer-octahedral configuration for this complex.
59 citations
TL;DR: In this paper, a new series of binuclear copper(II) complexes, [Fsal(=NenNR2)2Cu2X]2+ (R=Me and Et, X=Cl, Br, and OH), were synthesized, where Fsal( = NenNR 2)2 indicates the Schiff base prepared from 2,6diformyl-4-methylphenol and N,N-dialkylethylenediamine (alkyl=methyl(Me) and ethyl(Et)).
Abstract: A new series of binuclear copper(II) complexes, [Fsal(=NenNR2)2Cu2X]2+ (R=Me and Et, X=Cl, Br, and OH), were synthesized, where Fsal(=NenNR2)2 indicates the Schiff base prepared from 2,6-diformyl-4-methylphenol and N,N-dialkylethylenediamine (alkyl=methyl(Me) and ethyl(Et)). Two copper(II) ions are connected with the phenolic oxygen and X. The complexes obtained were characterized by elemental analyses, infrared and visible spectra, molar conductivities in methanol, ESR spectra and magnetic susceptibilities. It was found that the stability of the complexes decreases in the order X=OH>>Br>Cl. It was concluded from cryomagnetic measurements that the effect of the bridging group X on spin-coupling decreases in the order OH>>Br>Cl.
53 citations
TL;DR: Titanium(IV) chelates have been prepared by a novel method, reacting titanyl perchlorate with tridentate aromatic Schiff bases containing ONO sequences in this paper.
38 citations
36 citations
Patent•
26 Dec 1973TL;DR: In this article, the Schiff bases and N,N'-bis-imide compounds facilitate processing of prepolymer resins by lowering the softening temperature, under processing conditions, and chain-extend and cross-link the base resins.
Abstract: This invention provides compositions containing A. a polyimide and polyamide-imide terminated with olefinic unsaturated end groups, or the corresponding polyamide-acids in combination with a reactive Schiff base compound, and B. a polyimide and polyamide-imide terminated with a Schiff base end group or the corresponding polyamide acids in combination with a reactive N,N'-bis-imide. These Schiff bases and N,N'-bis-imide compounds facilitate processing of the prepolymer resins by lowering the softening temperature, under processing conditions, and chain-extend and cross-link the base resins.
30 citations
TL;DR: In this paper, it was shown that the title compound has a polymeric structure with the Schiff base acting as oxygen-bridged bidentate ligand, and that it is polymeric with a Schiff base.
29 citations
TL;DR: In this paper, a series of potentially pentadentate ligands derived from substituted salicylaldehydes and 2,2′-(aminoethyl)-sulfide, 3,3′-bis(aminopropyl) sulfide and diethylenetriamine have been prepared.
Abstract: Copper(II) complexes of a related series of potentially pentadentate ligands derived from substituted salicylaldehydes and 2,2′-(aminoethyl)-sulfide, 3,3′-bis(aminopropyl)sulfide, 3,3′-bis(aminopropyl)ether and diethylenetriamine have been prepared. Elemental analysis, mass, infrared and visible spectra and magnetic susceptibility measurements have been employed in order to characterize these new compounds. The materials appear to be monomeric in the solid state exhibiting no abnormal magnetic properties at room temperature. In comparison with the visible spectra of a series of known copper(II) complexes of tetradentate ligands, the structure of these complexes is postulated to be essentially square planar. However, the possibility of weak coordination by the middle donor in some of the pentadentate ligands can not be ruled out.
25 citations
22 citations
TL;DR: The tridentate SchifF base N-3-hydroxy-n-propylsalicylaldimine can be coordinated with copper(II) to form three kinds of dimeric oxy-bridged antiferromagnetic complexes (metal: ligand ratio 1: 1), as well as the normal monomeric complex as discussed by the authors.
Abstract: The tridentate SchifF base N-3-hydroxy-n-propylsalicylaldimine can be coordinated with copper(II) to form three kinds of dimeric oxy-bridged antiferromagnetic complexes (metal: ligand ratio—1: 1), as well as the normal monomeric complex. In one of the dimeric complexes pairs of copper atoms are bridged by pairs of the deprotonated alcoholic oxygens of the ligands. The others have an extra ligand X (X=–Cl, –ONO2) per copper atom, the metals are bridged by phenolic oxygens, the alcoholic hydroxyls are not deprotonated, but are either coordinated (if X=Cl) to five-coordinated copper atoms in discrete dimer molecules, or participate in intermolecular hydrogen bonding linking individual dimeric molecules in which the copper atoms are four-coordinated. In the presence of pyridine, ammonia, or mild inorganic base, a rearrangement reaction can be induced, resulting in conversion of the phenolic-bridged (five-coordinated copper) dimer into the related alcoholic-bridged (fourcoordinated copper) dimer. This behaviou...
TL;DR: Substitution of 3 CO groups in cis position to each other in M(CO)6 (M = Cr, Mo, W) by 3 ligands different from each other gives the chiral molecules cis-(CO)3ML1L2L3).
TL;DR: In this article, the asymmetric (enantioselective) hydrogenation process of acetylacetone (AA) was studied by the use of catalysts modified with D-tartaric acid, and L-glutamic acid.
Abstract: The asymmetric (enantioselective) hydrogenation process of acetylacetone (AA), which is a highly enolized compound, was studied by the use of catalysts modified with D-tartaric acid, and L-glutamic acid. AA corroded the Raney nickel catalyst during the hydrogenation. The modification protected the catalyst from corrosion, and the protective effects by the amino acids were greater than that by the hydroxy acid. The modification with tartaric acid increased the hydrogenation velocity of AA, but the amino acid hardly affected the hydrogenation velocity. The glutamic acid on the catalyst surface reacted with AA to form a Schiff base during the hydrogenation. The hydrogenation proceeded mainly by means of a two-step process via 2-pentanol-4-on. The modifying pH and temperature affected the asymmetric activity of the catalyst. In the first step of the hydrogenation, the catalyst modified with D-tartaric acid showed a high asymmetric activity, but the one modified with L-glutamic acid exhibited a low asymmetric ...
Patent•
06 Dec 1973TL;DR: In this article, the 4-amino aniline with a carboxylic acidamide or thioamide was used for the preparation of 4-acylaminophenylamidine.
Abstract: 4-Amino substituted phenylamidine are anthelmintics. The compounds, of which N-(4-aminophenyl)-N'',N''-dimethylacetamidine is a representative embodiment, can be prepared through treatment of a 4-amino aniline with a carboxylic acidamide or thioamide, reduction of an appropriately substituted 4-aminophenylamidine, optionally followed by alkylation of the resultant 4-aminophenylamidine, formation of a Schiff base followed by quaternization and hydrolysis, or hydrolysis of a 4-acylaminophenylamidine.
TL;DR: In this paper, the crystal structures of the title compounds have been determined from three-dimensional X-ray data by conventional Fourier methods and the structures were refined by least-squares methods to R 0·050 [(+)-form, 1226 observed reflections] and 0·033 (meso-form, 2301 observed reflections).
Abstract: The crystal structures of the title compounds have been determined from three-dimensional X-ray data by conventional Fourier methods. The crystals of the optically active form are orthorhombic, space group P212121. With Z= 4 and cell parameters a= 10·577, b= 16·725, and c= 9·603 A, whereas those of the meso-form are monoclinic, space group P21/c, with Z= 4 and cell parameters a= 10·566, b= 13·449, c= 12·300 A, and β= 108·2°. The structures were refined by least-squares methods to R 0·050 [(+)-form, 1226 observed reflections] and 0·033 (meso-form, 2301 observed reflections). The molecules of both compounds are similar, the cobalt atom having a square planar stereochemistry slightly tetrahedrally distorted. The main difference is found in the butylene bridge, the methyl groups being both pseudo-axial in the optically active form, but one pseudo-equatorial and the other pseudo-axial in the meso-form.
TL;DR: In this article, the reaction of the thallium derivatives of alkyl and aryl salicyladimines, TlSalNR, and the quadridentate Schiff base N,N ′-ethylenebis(salicylaldimine), Tl 2 -Salen, with [(N,N dimethylbenzylamine-2-C,N ) MCl] 2 ([DmbaMCl]2 ; M = Pd, Pt) give the complexes DmbaMSal
TL;DR: The anionisierte Schiff base 1a reacts with nitriles to give the primary enamines 4 and 5a-5c as discussed by the authors, after hydrolysis to 8a, is stable.
TL;DR: In this paper, the reactivity of methylene or methine groups in the dipeptide moieties of those Schiff base chelates has been investigated on the basis of their PMR spectra in D2O.
Abstract: Nickel(II) and cobalt(III) chelates of the Schiff bases derived from salicylaldehyde and dipeptides such as glycylglycine, glycylalanine and alanylglycine have newly been prepared The reactivity of methylene or methine groups in the dipeptide moieties of those Schiff base chelates has been investigated on the basis of their PMR spectra in D2O It has been confirmed that the methylene or methine protons of the N-terminal amino acid residue are more easily activated than those of the C-terminal amino acid residue
TL;DR: In this paper, the X-band e.s.r. spectra due to the copper(II) Schiff-base complexes, namely bis(N-methylsalicylaldiminato)-copper(II), NN′-ethylenebis(Salicylideneiminiato)copper, NN-phenylenebis(saliclyideneinato) copper, and NN−phenyleneis(o-aminobenzylidenesinato-copper) in chloroform solution at 77 K exhibit
Abstract: The X-band e.s.r. spectra due to the copper(II) Schiff-base complexes, namely bis(N-methylsalicylaldiminato)-copper(II), NN′-ethylenebis(salicylideneiminato)copper(II), NN′-phenylenebis(salicylideneiminato)copper(II), NN′-ethylenebis(o-aminobenzylideneiminato)copper(II), and NN′-phenylenebis(o-aminobenzylideneiminato)-copper(II) in chloroform solution at 77 K exhibit low-field lines, which are attributed to ΔMs=±2 transitions within the triplet state due to dimeric forms of these complexes which exist in frozen solution. The salient features of the low-field lines have been satisfactorily accounted for by means of computer simulated spectra based on dipole–dipole coupled pairs of copper(II) ions in dimers with lower than axial symmetry. The results obtained for the internuclear separations of the copper(II) ions are compared with those obtained from crystallographic data.
Patent•
03 Oct 1973TL;DR: In this paper, Disclosure Crosslinked resins are prepared by reacting an N,N'-bis-imide and a Schiff base at a temperature of from 100°C to 280°C.
Abstract: of the Disclosure Crosslinked resins are prepared by reacting an N,N'-bis-imide and a Schiff base at a temperature of from 100°C to 280°C. The crosslinked resins have good thermal stability and are useful for making ad-hesives, coatings, laminates and molded articles.
TL;DR: In this article, it was shown that Schiff base ligands containing glycyl glycine (Gly·Gly), glycyl-β-alanine (β-Ala·β-ala) or β-alanylglycine as the peptide moieties give rise to square-planar, quadridentate copper(II)- and nickel(II)chelates.
Abstract: Copper(II) and nickel(II) complexes of Schiff bases derived from salicylaldehyde(Sal) and dipeptides containing glycine and/or β-alanine have been prepared. It has been found that Schiff base ligands containing glycylglycine (Gly·Gly), glycyl-β-alanine (Gly·β-Ala) or β-alanylglycine (β-Ala·Gly) as the peptide moieties give rise to square-planar, quadridentate copper(II)- and nickel(II)-chelates, while the N-salicylidene-β-alanyl-β-alanine (Sal=β-Ala·β-Ala) does not form the same type of copper(II)- or nickel(II)-chelate. It is concluded on the basis of spectrophotometric, polarographic and other measurements that the stability decreases in the order 6-5-5-([Cu(Sal=Gly·Gly)])≥6-5-6-([Cu(Sal=Gly·β-Ala)])≥6-6-5-([Cu(Sal=β-Ala·Gly)])>>6-6-6-([Cu(Sal=β-Ala·β-Ala)])fused-ring system.
TL;DR: The large variations in the rates of the copper-II-promoted solvolyses of various nickel(II) complexes, containing Schiff base ligands with varying diamine substituents, is attributed to steric effects as discussed by the authors.
Abstract: The large variations in the rates of the copper(II)-promoted solvolyses of various nickel(II) complexes, containing Schiff base ligands with varying diamine substituents, is attributed to steric effects. The important rate differences occur for reactants whose stereochemistries and electronic properties appear little different. However, the steric effects cannot be viewed definitely from either nickel-diamine dissociation or copper-diamine formation. Nickel reactants which may be distorted from planarity give trimeric products on reaction with copper in dmso and dmf, if the reactions are carried out at high initial concentration ratios of copper(II) to nickel complex. Ligand substitution studies indicate a differing reactivity sequence for the diamine-substituted ligands in their capacities as entering, compared to leaving, groups.
TL;DR: In this article, anionic dimethylplatinum (IV) complexes with bidentate N -organosalicylaldimines of the form [Me 2 PtX 2 (Sal=N-R)] − (X=Br, Cl) have been synthesized from Me 2 Pt X 2 and isolated as thallium, tetraalkylammonium and tetraphenyl arsonium salts.
TL;DR: In this article, the preparations of a series of nickel(II) and copper (II) complexes containing tridentate and tetradentate Schiff base ligands are reported.
Abstract: The preparations of a series of nickel(II) and copper(II) complexes containing tridentate and tetradentate Schiff base ligands are reported. Some solid and solution characterization studies are included.
TL;DR: In this paper, a new class of mixed ligand complexes of nickel(II) was reported, which have the stoichiometry LKNi where L is a potentially tridentate Schiff base anion and K is the corresponding bidentate carbonyl species.
TL;DR: In this paper, single crystal susceptibility studies on the oxygen-inactive compounds Co salen and Co salin (py) have been made over the temperature range 320-100°K.
TL;DR: Vanadium(III) Schiff base chelates of the types V(chel)Cl,py (chel = saen, saph) and V(saen)CL,py2 have been synthesized by allowing VCl3 and the ligand to react in pyridine solutions as mentioned in this paper.
Abstract: Vanadium(III) Schiff base chelates of the types V(chel)Cl,py (chel = saen, saph) and V(saen)Cl,py2 have been synthesized by allowing VCl3 and the ligand to react in pyridine solutions. The bromo derivatives V(saen)Br,py and V(saph)Br,py2 can be obtained by LiBr substitution. The magnetic and spectral properties of the complexes are consistent with tetragonally distorted octahedral structures, though the μeff value for V(saen)Cl,py is slightly lower than expected and difficult to explain with certainty.
01 Jan 1973
TL;DR: Some of the metabolic requirements for rapid complete regeneration of photosensitive pigment in preparations of bleached bovine photoreceptors incubated with all-trans retinal are indicated.
Abstract: The mechanism of visual pigment regeneration during dark adaptation has remained obscure despite sporadic study in a number of laboratories (1–7). It has, however, been clearly established (8) that the apoprotein of rhodopsin reacts spontaneously with 11-cis retinal to regenerate the visual pigment. If 11-cis retinal arises through the direct geometrical isomerization of all-trans retinal, it would then seem reasonable to look for the occurence of such a reaction in photoreceptor outer segments where the Schiff base, metarhodopsin II, and possibly free all-trans retinal occur transiently as a result of visual pigment bleaching. Our recent studies (9, 10) indicate some of the metabolic requirements for rapid complete regeneration of photosensitive pigment in preparations of bleached bovine photoreceptors incubated with all-trans retinal.