Enhancing the Stability of Hydrogels by Doubling the Schiff Base Linkages

2018 ◽  
Vol 220 (3) ◽  
pp. 1800484 ◽  
Author(s):  
Xiaoya Ding ◽  
Gao Li ◽  
Chunsheng Xiao ◽  
Xuesi Chen
Keyword(s):  
Schiff Base ◽  
The Stability

Schiff base equilibria. II. Beryllium complexes of N-n-butylsalicylideneimine and the hydrolysis of the Be2+ ion

1965 ◽  
Vol 18 (5) ◽  
pp. 651 ◽  
Author(s):  
RW Green ◽  
PW Alexander
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Complex Formation ◽  
Distribution Coefficient ◽  
Dilute Aqueous Solution ◽  
The Stability ◽  
Ph Range ◽  
Hydrolysis Of ◽  
Beryllium Complexes ◽  
Equilibria In Aqueous Solution

The Schiff base, N-n-butylsalicylideneimine, extracts more than 99.8% beryllium into toluene from dilute aqueous solution. The distribution of beryllium has been studied in the pH range 5-13 and is discussed in terms of the several complex equilibria in aqueous solution. The stability constants of the complexes formed between beryllium and the Schiff base are log β1 11.1 and log β2 20.4, and the distribution coefficient of the bis complex is 550. Over most of the pH range, hydrolysis of the Be2+ ion competes with complex formation and provides a means of measuring the hydrolysis constants. They are for the reactions: Be(H2O)42+ ↔ 2H+ + Be(H2O)2(OH)2, log*β2 - 13.65; Be(H2O)42+ ↔ 3H+ + Be(H2O)(OH)3-, log*β3 -24.11.

scholarly journals Complexes of some 3d-metals with a Schiff base derived from 5-acetamido-1,3,4-thiadiazole-2-sulphonamide and their biological activity

2011 ◽  
Vol 76 (10) ◽  
pp. 1387-1394 ◽  
Author(s):  
Suman Malik ◽  
Suparna Ghosh ◽  
Liviu Mitu
Keyword(s):  
Schiff Base ◽  
Fungicidal Activity ◽  
Particle Size Analysis ◽  
Bidentate Ligand ◽  
Octahedral Geometry ◽  
Spectral Studies ◽  
Size Analysis ◽  
3D Metals ◽  
Complexes Of Transition Metals ◽  
The Stability

Using a bidentate ligand, a Schiff base of 5-acetamido-1,3,4- thiadiazole-2-sulphonamide, complexes of transition metals having the general formula ML2, where M = Mn(II), Fe(II), Ni(II) and Cu(II), were synthesized. The complexes were characterized by elemental analysis, molar conductivity, magnetic moment, electronic, ESR and IR spectroscopy, and particle size analysis. The conductivity data of the complexes suggests their non-electrolytic nature. The stability constants and free energy change for the complexes were calculated. Spectral studies and magnetic susceptibility measurements revealed an octahedral geometry for all the complexes. The ligand and its complexes were screened for their fungicidal activity against Aspergillus niger and A. flavus.

scholarly journals Potentiometric and spectrophotometric studies of the complexation of Schiff-base hydrazones containing the pyrimidine moiety

2003 ◽  
Vol 68 (10) ◽  
pp. 729-749 ◽  
Author(s):  
H.S. Seleem ◽  
B.A. El-Shetary ◽  
S.M.E. Khalil ◽  
M. Shebl
Keyword(s):  
Schiff Base ◽  
Ionic Strength ◽  
Thermodynamic Parameters ◽  
Stability Constants ◽  
Elemental Analysis ◽  
Mass Spectra ◽  
Dissociation Constants ◽  
The Stability ◽  
Pyrimidine Moiety ◽  
Metal Ligand

Three Schiff-base hydrazones (ONN ? donors) were prepared by condensation of 2-amino-4-hydrazino-6-methylpyrimidine with 2-hydroxyacetophenone 2-methoxybenzaldehyde and diacetyl to yield 2-OHAHP, 2-OMeBHPand DHP respectively. The structures of these ligands were elucidated by elemental analysis, UV, IR, 1H-NMR and mass spectra. The metal?ligand stability constants of Mn2+, Fe3+,Co2+,Ni2+,Cu2+, Zn2+,Cd2+,UO22+ and Th4+ chelates were determined potentiometrically in two different media (75%(v/v) dioxane?water and ethanol?water) at 283, 293, 303 and 313 K at an ionic strength of 0.05 M (KNO3). The thermodynamic parameters of the 1:1 and 1:2 complexes were evaluated and are discussed. The dissociation constants of 2-OHAHP, 2-OMeBHP and DHPligands and the stability constants of Co2+, Ni2 and Cu2+ with 2-OHAHP were determined spectrophotometrically in 75 % (v/v) dioxane?water.

Schiff base equilibria. V. Beryllium complexes of N-ethylsalicylideneimine

1966 ◽  
Vol 19 (11) ◽  
pp. 2101 ◽  
Author(s):  
RW Green ◽  
RJ Sleet
Keyword(s):  
Schiff Base ◽  
Distribution Coefficient ◽  
Stability Constants ◽  
Formation Constant ◽  
Mixed Complex ◽  
High Ph ◽  
The Stability ◽  
Hydrolysis Of ◽  
Beryllium Complexes

The formation constant and pK at 25� of the Schiff base N- ethylsalicylideneimine (HL) have been found by spectrophotometry to be 2.75x104 and 11.8 respectively. The distribution coefficient of the base from water into toluene is 160. The stability constants of the beryllium complexes determined by solvent distribution are logβ1 10.4 and log β2 18.3, and the distribution coefficient of BeL2 is 260. At high pH the equilibria are complicated by hydrolysis of the Be2+ ion and by formation of the mixed complex, BeL(OH)-2. The latter is formed according to the reaction BeL(H2O)+2 ↔ BeL(OH)-2+2H+ with logKm2 -18.4.

scholarly journals Intra-molecular Interactions in Porous Covalent Organic Frameworks

2014 ◽  
Vol 70 (a1) ◽  
pp. C530-C530
Author(s):  
Rahul Banerjee
Keyword(s):  
Hydrogen Bonding ◽  
Schiff Base ◽  
Molecular Interactions ◽  
Chemical Stability ◽  
Intramolecular Hydrogen Bonding ◽  
Covalent Organic Frameworks ◽  
Covalent Organic Framework ◽  
New Strategy ◽  
The Stability ◽  
Intramolecular Hydrogen

A new strategy of intramolecular hydrogen bonding in 2D covalent organic framework as an extra stabilizing factor has been introduced, which helps to improve the crystallinity, porosity and chemical stability of the COF. Using this concept, highly stable porphyrin containing covalent organic frameworks have been synthesized using the Schiff base reaction. The stability of the COFs mainly arises due to the strong intramolecular O-H...N=C hydrogen bonding. Validation of this postulate was cross-checked by synthesizing methoxy (OCH3) substituted COF in which no hyrogen bonding exists. It was found that methoxy substituted COF have a low crystallinity, porosity and chemical stability as compared to hydrogen bonded COF.

scholarly journals Design and Development of Complexation of Ce+3 Metal Ions with Synthesized INZ Incorporated Bio-active Schiff Bases

2021 ◽  
Vol 11 (4) ◽  
pp. 3989-4006
Keyword(s):  
Schiff Base ◽  
Metal Ions ◽  
Schiff Bases ◽  
Elemental Analysis ◽  
Metal Ion ◽  
Organic Ligands ◽  
Schiff Base Complexes ◽  
Spectral Techniques ◽  
The Stability ◽  
Antibacterial And Antifungal

In the present research, a series of Ce+3 metal ions complexation with INZ incorporating Schiff bases have been reported. INZ incorporated Schiff Bases (3a-e) were developed by condensing INZ with substituted aromatic aldehyde and confirmed with various spectral Techniques such as Elemental analysis, UV, IR, 1H-NMR, 13H NMR. All the synthesized organic ligands were evaluated against antibacterial and antifungal stains and found moderate to significant results. The Ce+3 metal ion solution mixed with newly prepared bio-active INZ Schiff bases (3a-e) to afford the [Ce-INZ Schiff Base] complexes (4a-e). The stability constants of prepared complexes were evaluated and found in order as a (3e) > (3d) > (3a) > (3b) > (3c).

Spectral, Magnetic and Thermogravimetric Studies of Some Dimeric Oxovanadium(IV) Complexes

1986 ◽  
Vol 41 (11) ◽  
pp. 1443-1446
Author(s):  
P. K. Nath ◽  
N. C. Mishra ◽  
V. Chakravortty ◽  
K. C. Dash
Keyword(s):  
Thermal Decomposition ◽  
Schiff Base ◽  
Ir Spectra ◽  
Magnetic Moment ◽  
Epr Spectroscopy ◽  
Anthranilic Acid ◽  
Room Temperature ◽  
Thermogravimetric Studies ◽  
Epr Signal ◽  
The Stability

Abstract The tridentate dibasic Schiff base anthranilic acid salicylideneimine (H2SB) reacts with VOCl2 in the presence o f NaOAc and imidazole (or its derivatives) to form dimeric oxovanadium (IV) complexes of the type [VO(S B)(D)]2. These green or yellow -green compounds have a magnetic moment of 1.4 B.M . at room temperature, and are non-electrolytes in MeOH . The compounds are characterised on the basis of electronic and IR spectra as well as EPR spectroscopy. The IR spectra shows a strong band due to v(V = O) at 880 cm-1 in addition to the bands of H2SB and imidazole. [VO(SB)(Im)]2 shows a single unresolved EPR signal at g = 1.9715 whereas compounds containing other imidazole derivatives show both a broadening and shifting of the signal. The thermogravimetric measurements indicate the stability of the complexes and their stepwise thermal decomposition.

A one-dimensional coordination polymer based on a di-Schiff base supported trinuclear CuIIsubunit

2012 ◽  
Vol 68 (4) ◽  
pp. m97-m99
Author(s):  
Liangliang Zhang ◽  
Fuling Liu ◽  
Shuai Yuan ◽  
Xiaoyang Wang ◽  
Di Sun
Keyword(s):  
Schiff Base ◽  
Coordination Polymer ◽  
Hydrogen Bonds ◽  
Crystal Packing ◽  
The Other ◽  
Stacking Interactions ◽  
Dimensional Chain ◽  
One Dimensional ◽  
The Stability ◽  
Methyl Benzene

A novel one-dimensional CuIIcoordination polymer,catena-poly[bis(μ4-3-{[2-(3-hydroxy-2-oxidobenzylidene)hydrazinylidene]methyl}benzene-1,2-diolato)dimethanoltricopper(II)], [Cu3(C14H10N2O4)2(CH3OH)2]n, (I), was constructed with a di-Schiff base supported centrosymmetric trinuclear CuIIsubunit. In the subunit, two peripheral symmetry-related CuIIcations have square-pyramidal CuNO4geometry and the central third CuIIcation lies on an inversion centre with octahedral CuN2O4geometry. In (I), each partially deprotonated di-Schiff base 3-{[2-(3-hydroxy-2-oxidobenzylidene)hydrazinylidene]methyl}benzene-1,2-diolate ligand (Hbcaz3−) acts as a heptadentate ligand to bind the CuIIcentres into chains along theaaxis. A centrosymmetric Cu2O2unit containing an asymmetrically bridging O atom, being axial at one Cu atom and equatorial at the other Cu atom, links the trinuclear CuIIsubunit into a one-dimensional chain, which is reinforced by intramolecular phenol–methanol O—H...O and methanol–phenolate O—H...O hydrogen bonds. Interchain π–π stacking interactions between pyrocatechol units, with a distance of 3.5251 (18) Å, contribute to the stability of the crystal packing.

SYNTHESIS OF NOVEL CROSS-LINKED POLYURETHANE CONTAINING MODIFIED STILBENE AND SCHIFF BASE CHROMOPHORES FOR SECOND-ORDER NONLINEAR OPTICS

2006 ◽  
Vol 15 (02) ◽  
pp. 275-285 ◽  
Author(s):  
MINGXIN YE ◽  
LEI XU ◽  
LIYONG JI ◽  
LIYING LIU ◽  
WENCHENG WANG
Keyword(s):  
Schiff Base ◽  
Physical Properties ◽  
Functional Groups ◽  
Potential Application ◽  
Frequency Doubling ◽  
Optical Nonlinearity ◽  
Second Order ◽  
Film Forming ◽  
The Matrix ◽  
The Stability

The cyano and nitro groups were chosen as acceptor groups, and the substituent amino or ether groups as donor groups to the matrix. Polyurethane (PU) was modified by glycerol to increase the content of chromophore and to improve the stability of the nonlinearity. T g and T m were raised and solubility, film-forming ability and other physical properties were improved. The average functional groups of the reactant can be adjusted to ≥ 2 with polygroups and monogroups mixture. These poled polymers show high second-order optical nonlinearity and would have potential application in frequency-doubling or electro-optical controlling devices.

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