Showing papers on "Schiff base published in 1978"
78 citations
66 citations
TL;DR: A series of ligands have been formed by the 1 : 1 molar condensation of salicylaldehyde (sl) with the diamines, propane-1, 3-diamine (p), butane- 1, 4diamines (b), and 2,5-dimethylhexane-2, 5-chloro-salicylamide (SLS)nickel(II) as mentioned in this paper.
Abstract: A series of ligands has been formed by the 1 : 1 molar condensation of salicylaldehyde (sl) with the diamines, propane-1,3-diamine (p), butane-1,4-diamine (b) and 2,5-dimethylhexane-2,5-diamine (d). The potentially tridentate ligands are o-[N-(3- aminopropyl)formimidoyl]phenol (Hslp), o-[N-(4- aminobutyl)formimidoyl]phenol (Hslb) and o-[N-(4-amino-1,1,4- trimethylpentyl)formimidoyl]-phenol (Hsld), respectively. These form the bis-nickel(II) complexes Ni(slp)2, Ni(slb)2 and Ni(sld)2. All appear to have octahedral structures in the solid. Ni(slb)2 occurs in yellow and green forms in the solid. In solution Ni(sld)2 occurs in equilibrium between tetrahedral (amines uncoordinated) and an octahedral centrosymmetric form with facially bound sld ligands. Ni(slp)2 reacts with bis(5-chloro-salicylaldehyde)nickel(II) to give the unsymmetrical four-coordinate nickel complex formed from the 1 : 1 : 1 molar condensation of salicylaldehyde, propane-1,3-diamine and 5- chlorosalicylaldehyde. A dimeric, amido bridged complex has been produced by the vacuum thermolysis of Ni(slp)2. Mass spectroscopic evidence is cited for the formation of the analogous dimeric complexes from Ni(slb)2 and Ni(sld)2.
64 citations
TL;DR: In this paper, new salicylaldimine chelates of divalent and trivalent ruthenium have been synthesized from RuCl2(PPh3)3.
Abstract: New salicylaldimine chelates of divalent and trivalent ruthenium have been synthesized from RuCl2(PPh3)3. The RuII complex trans- Ru(salen)(PPh3)2 is stable in the solid but very unstable to oxidation in solution. The RuIII derivative, Ru(salen)Cl(PPh3), displays magnetic and e.s.r. properties consistent with a low-spin d5 system under a ligand-field of rhombic symmetry.
58 citations
51 citations
TL;DR: In this paper, a mechanism for the interaction is proposed in which the interacting protein group in an unprotonated configuration is complexed through Schiff base proton to the Schiff base nitrogen, which results in the deprotonation of an amino acid side chain with pK > 10.2 ± 0.3.
Abstract: Resonance Raman spectroscopy of the retinylidene chromophore in various isotopically labeled membrane environments together with spectra of isotopically labeled model compounds demonstrates that a secondary protein interaction is present at the protonated Schiff base linkage in bacteriorhodopsin. The data indicate that although the interaction is present in all protonated bacteriorhodopsin species it is absent in unprotonated intermediates. Furthermore, kinetic resonance Raman spectroscopy has been used to monitor the dynamics of Schiff base deprotonation as a function of pH. All our results are consistent with lysine as the interacting group. A structure for the interaction is proposed in which the interacting protein group in an unprotonated configuration is complexed through the Schiff base proton to the Schiff base nitrogen. These data suggest a molecular mechanism for proton pumping and ion gate molecular regulation. In this mechanism, light causes electron redistribution in the retinylidene chromophore, which results in the deprotonation of an amino acid side chain with pK >10.2 ± 0.3 (e.g., arginine). This induces subsequent retinal and protein conformational transitions which eventually lower the pK of the Schiff base complex from >12 before light absorption to 10.2 ± 0.3 in microseconds after photon absorption. Finally, in this low pK state the complex can reprotonate the proton-deficient high pK group generated by light, and the complex is then reprotonated from the opposite side of the membrane.
47 citations
TL;DR: The Schiff base NN′-ethylenebis (salicylideneimine) and related bases, H2L, react with hydrated lanthanoid(III) halides to give the complexes Ln(H2L)Cl3·nH2O (Ln = La or Ce; n= O-2), Ln2(H 2L)3Cl6·n H2O(Ln= La, Ce, Pr, Nd, Sm, Gd, Ho, or Yb; X = Cl or Br
Abstract: The Schiff base NN′-ethylenebis(salicylideneimine) and related bases, H2L, react with hydrated lanthanoid(III) halides to give the complexes Ln(H2L)Cl3·nH2O (Ln = La or Ce; n= O—2), Ln2(H2L)3Cl6·nH2O (Ln = La, Ce, Pr, Nd, Sm, Gd, Ho, or Yb; n= O–2). Ln(H2L)2X3·nH2O (Ln = La, Ce, Pr, Nd, Sm, Gd, Ho, or Yb; X = Cl or Br; n= O–2). and Ln(H2L)3X3·nH2O (Ln = La, Ce, Pr, Nd, Sm. or Gd; X = Cl or Br; n= 0 or 1). Spectroscopic and other evidence has indicated that: (i) halide is co-ordinated to the metal ion except in the case of Ln(H2L)3X3·nH2O where the results were ambiguous; and (ii) the potentially quadridentate ligands are bidentate in these complexes with the un-ionised phenolic groups being unco-ordinated.
45 citations
TL;DR: In this paper, the interaction of dichlorotris(triphenylphosphine)ruthenium(II) with the sodium salts of various Schiff bases leads to complexes of the type trans-RuL(PPh3)2 for the quadridentate bifunctional ligands and RuL2(pPh3), for the bifunctions.
Abstract: The interaction of dichlorotris(triphenylphosphine)ruthenium(II) with the sodium salts of various Schiff bases leads to complexes of the type trans-RuL(PPh3)2 for the quadridentate bifunctional ligands and RuL2(PPh3)2 for the bifunctional ligands.Interaction of the chloro-carbonyls, {Ru(CO)2Cl2}n or {Ru(CO)3Cl2}3, with the sodium salt of NN′-ethylenebis-(salicylideneimine), (sal2enH2), yields the pale yellow complex cis-Ru(sal2en)(CO)2.Interaction of the bicyclo[2.2.1]hepta-2,5-diene (norbornadiene) complex {Ru(nbd)Cl2}n with Na2(sal2en) yields Ru(sal2en)(nbd) which has a non-planar ligand structure.I.r. and 1H and 31P n.m.r. spectra of the various complexes are given and structures for the compounds proposed.
40 citations
36 citations
TL;DR: In this article, the authors studied the fluorescence properties of some metal complexes with aromatic Schiff base compounds and found that substitution of o,p-orientating substituents at p-position to -CH- group of Schiff bases increased relative fluorescence quantum yield, fluorescence sensitivity index, rate constant for the process of fluorescence emission, and molar extinction coefficient of the complexes.
35 citations
TL;DR: In this paper, a new ligand, referred to as H 4 aapen, has been prepared; it is the ethylenediamine Schiff base derivative of o -acetoacetylphenol and has one site with two nitrogen and two oxygen atoms (N 2 O 2 ) and a second site with four oxygens being common to both sites.
TL;DR: In this article, the Schiff base ligand derived from S-benzyldithiocarbazate (NH2-NH-CSSCH2C6H5) has been prepared and characterized by elemental analyses, magnetic, conductometric, ir, and electronic spectral studies.
Abstract: New complexes with the Schiff base ligand derived from S-benzyldithiocarbazate (NH2—NH—CSSCH2C6H5) have been prepared and characterized by elemental analyses, magnetic, conductometric, ir, and electronic spectral studies. The tridentate ONS Schiff base S-benzyl-β-N-(phenyl, phenylhydroxymethyl)methylenedithiocarbazate gave mono-ligand complexes with Ni(II) and Cu(II) having the general formula [MligandX] (M = Ni(II) and Cu(II); X = NO3, Cl, Br, NCS). A proposed square-planar structure for the nickel complexes is supported by magnetic and spectral data. A square-planar structure is also suggested for Cu(II) complexes. The ir results give evidence of the different bondings present in the complexes.
Patent•
11 Dec 1978TL;DR: The polydentate amine ligand systems are useful for synthesis of chelating agents for sequestering metal ions from solution for purification or concentration purposes as discussed by the authors. But the amine is a precursor for other ligand system; for example, the primary amine groups formed condense with an aldehyde or ketone to yield five coordinate Schiff base ligands.
Abstract: Polymer bound multidentate complexes are prepared by reacting pendant benzyl chloride and benzyl iodide groups on a variety of polymer supports, including crosslinked polystyrene, with 3,3'-iminodiproprionitrile and reducing the nitrile groups by treatment with, for example, a boron hydride-tetrahydrofuran complex to form the amine. The amine is a precursor for other ligand systems; for example, the primary amine groups formed condense with an aldehyde or ketone to yield five coordinate Schiff base ligands. The polydentate amine ligand systems are useful for synthesis of chelating agents for sequestering metal ions from solution for purification or concentration purposes. Metal complexes of these ligands with manganese, iron, cobalt, nickel, copper, and zinc can be prepared which are useful as heterogeneous oxidation catalysts.
TL;DR: The Schiff bases a-(C5H4N)CMe=NNHCOR (R = Ph, 2-thienyl or Me), prepared by condensation of 2-acetylpyridine with the acylhydrazines RCONHNH2, coordinate in the deprotonated iminol form to yield the octahedral complexes, M[NNO]2 M = Co or Ni; [NNOH] = Schiff base and the square-planar complexes, Pd[NO]Cl. as discussed by the authors.
Abstract: The Schiff bases a-(C5H4N)CMe=NNHCOR (R = Ph, 2-thienyl or Me), prepared by condensation of 2-acetylpyridine with the acylhydrazines RCONHNH2, coordinate in the deprotonated iminol form to yield the octahedral complexes, M[NNO]2 M = Co or Ni; [NNOH] = Schiff base and the square-planar complexes, Pd[NNO]Cl. The Schiff bases also coordinate in the neutral keto form yielding the octahedral complexes (M[NNOH]2)Z2 (M = Ni, Co or Fe; Z = C104, BF4 or N03) and complexes of the type M[NNOH]X2 (M = Ni, Co, Fe or Cu; X = Cl, Br or NCS). Spectral and x-ray diffraction data indicate that the complexes M[NNOH]X2 (M = Ni or Fe) are polymeric octahedral, as are the corresponding cobalt complexes having R = 2-thienyl. However, the cobalt complexes Co[NNOH]X2 (X = CI or Br; R = Ph or Me) and the copper complexes Cu[NNOH]CI2 (R = Ph, 2-thienyl or Me) are five-coordinate, while the thiocyanato complex Co[NNOH](NCS)2 (R = 2-thienyl) is tetrahedral.
TL;DR: In this paper, a square-planar structure for the NiO2N2 chromophore was derived from magnetic and spectroscopic evidence, and the copper(II) complex, Cu(HONNSR)Br2 containing the neutral Schiff base ligand was also isolated.
TL;DR: Tetra-coordinated Schiff base complexes of boron of the general type (OAc)2B(SB) have been synthesized by the reaction between boric acid and the Schiff base in acetic anhydride medium as mentioned in this paper.
TL;DR: Kinetic resonance Raman spectroscopy as a function of pH has been utilized and it is shown that the pK of Schiff base deprotonation is between 9.9 and 10.3, microseconds after light absorption and is >12 before photon initiation of photochemical cycling associated with proton pumping.
TL;DR: In this article, the formation of Schiff bases from the reaction of primary amines and several aromatic aldehydes has been studied, and 2-fluorenealdehyde was found to be suitable fluorigenic reagents for primary aliphatic amines, forming Schiff bases that were very stable and intensely fluorescent in acidic ethanol.
TL;DR: In this article, the preparation of several N2S2 Schiff base complexes of copper(II) is described and a comparison of the electron spin resonance and optical spectra of the N 2S2 compounds and the corresponding N 2O2 compounds is made.
TL;DR: In this article, the properties of the Schiff base ligands of 2-hydroxy-1-naphthaldehyde with N-methyl-S-alkyldithiocarbazates were characterized by elemental analysis and magnetic and spectroscopic measurements.
TL;DR: In this article, the tetradentate Schiff bases were used to give almost quantitative yields of I)is-salicylaldehyde-o-phenylenediimine (SBH2 ) and bis-Salicyl-aldehyde-p-phenyllencdiimines (S′B′H2) in anhydrous benzene in 1: 1 and 1 : 2 molar ratios.
Abstract: Titanium and zirconium isopropoxides react with the tetradentate Schiff bases, I)is-salicylaldehyde-o-phenylenediimine (SBH2 ) and bis-salicylaldehyde-p-phenylencdiimine (S′B′H2) in anhydrous benzene in 1: 1 and 1 :2 molar ratios to give almost quantitative yields of M(OPr-i)2 (SB) and M(OPr-i)2(SB)(SBH), where M = Ti or Zr and [SB]2 is the anion of the corresponding Schiff base, SBH2. The i.r. spectra of the completes have been recorded and tentative assignments for C=N and C-O stretching frequencies made.
TL;DR: In this paper, the coordination of metal chelates to tin involves two triply bonded oxygen atoms giving rise to an octahedral environment around SnIV and phenyltin(IV) chlorides.
Abstract: Binuclear complexes of phenyltin(IV) chlorides with transition metal chelates of tetradentate Schiff bases derived from acetylacetone, benzoylacetone oro-hydroxyacetophenone and ethylenediamine or propylenediamine, of the general formula PhnSnCl4-nML (where n = 1 or 2, M = Ni11 or Cu11 and L2−= the Schiff base dianion), have been synthesised and characterized through elemental analysis, conductance and i.r. spectroscopic data. The coordination of metal chelates to tin involves two triply bonded oxygen atoms giving rise to an octahedral environment around SnIV. The molar conductance of the complexes in nitrobenzene shows the presence of the uncoordinated ML and phenyltin(IV) chloride moieties in solution.
TL;DR: In this paper, the preparation of iron(II) complexes of bi-, tri-, quadri-, quinque-, and sexi-dentate Schiff bases is reported. But the reaction of these complexes with cyanide is not discussed.
Abstract: Preparations of iron(II) complexes of bi-, tri-, quadri-, quinque-, and sexi-dentate Schiff bases are reported. The Schiff-base ligands are derived from pyridine-2-carbaldehyde, phenyl 2-pyridyl ketone, pyridine-2,6-dicarb-aldehyde. or 2,6-diacetylpyridine, and appropriate amines. All these complexes aquate in acid solution, and react with cyanide to give ternary iron(II)–cyanide–Schiff-base complexes. The kinetics of aquation of several of these Schiff-base complexes, and the kinetics of cyanide attack at all the complexes, are described, and reactivities are compared with those for analogous reactions of other iron(II) di-imine complexes. Solvent effects on the re-activity with cyanide of one of the complexes of the sexidentate Schiff bases in a range of binary aqueous mixtures are discussed.
TL;DR: In this paper, the Schiff base 13 was formed by reaction of 3a with fluorenone, and 3a and 3b yielded azomethines 12a and 12b.
TL;DR: Tetra-coordinated diacetoxy-boron Schiff base derivatives of the type (AcO)2B(SB) have been synthesized in almost quantitative yields and in a state of sufficient purity by the equimolar ratio reactions of boric acid and Schiff bases in acetic anhydride medium.
Abstract: Tetra-coordinated diacetoxy-boron Schiff base derivatives of the type (AcO)2B(SB) (where SB− is the anion of the corresponding monofunctional bidentate Schiff base, SBH) have been synthesized in almost quantitative yields and in a state of sufficient purity by the equimolar ratio reactions of boric acid and Schiff bases in acetic anhydride medium. Even on mixing the reactants in higher molar ratio only 1:1 derivatives could be isolated. On the basis of elemental analyses, molecular weight determinations and conductance measurements and infrared and proton magnetic resonance spectra, the possible structures for the resulting new derivatives have been indicated.
TL;DR: In this article, the template condensation of 1,11-diamino-3,6,9-trioxaundecane with pyridine-2,6-dicarbaldehyde was used to construct thiocyanate complexes and the ready exchange of alkaline earth cations for lead(II) in these complexes was reported.
Abstract: Novel alkaline earth metal thiocyanate complexes are formed by the template condensation of 1,11-diamino-3,6,9-trioxaundecane with pyridine-2,6-dicarbaldehyde; the X-ray structures of (3,15,21-triaza-6,9,12-trioxabicyclo [15.3.1]heneicosa-1(21), 2, 15, 17, 19-pentaene)di-isothiocyanatocalcium(II) and aqua-(3,15,21-triaza-6,9,12-trioxabicyclo[15.3.1]heneicosa-1(21),2,15,17,19-pentaene)di-isothiocyanatostrontium(II) have been determined and the ready exchange of alkaline earth cations for lead(II) in these complexes is reported.
TL;DR: In this article, the synthesis of isomeric copper(II) Schiff base complexes formed by the condensation of 1-and 2-adamantanamines with salicylaldehyde, o-vanillin and pyrrole-2-carboxaldehyde is described.
TL;DR: In this article, the reaction of high surface area silica, dehydrated at 140°C, with the amines, NH 2 (CH 2 ) 3 Si(OCH 2 CH 3 ) 3 and NH 2(CH 2 ), 4 Si(CH 3 ) 2 (OCH 3 ).