scholarly journals Schiff base equilibria. VII. Formation and distribution of N-(β-Hydroxyethyl)salicylideneimine

1969 ◽  
Vol 22 (5) ◽  
pp. 917 ◽  
Author(s):  
RW Green ◽  
RJ Sleet
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Formation Constant ◽  
Equilibrium Constants

The formation constant and pK of the Schiff base N-(8- hydroxyethyl)salicylideneimine in aqueous solution at 25� have been determined spectrophotometrically to be 5.01 x 103 and 11.4 respectively. These equilibrium constants have been used to account for the distribution of the imine between water and chloroform.

Schiff base equilibria. VI. n- and t-Butylimines of pyridine-2-aldehyde

1968 ◽  
Vol 21 (10) ◽  
pp. 2427 ◽  
Author(s):  
RW Green ◽  
MJ Rogerson
Keyword(s):  
Schiff Base ◽  
Schiff Bases ◽  
Formation Constant ◽  
Equilibrium Constants

Equilibrium constants at 25� have been measured for the formation of Schiff bases of pyridine-2-aldehyde with n-butylamine (1.45 x 108) and t-butylamine (93). The Schiff base of salicylaldehyde with t-butylamine has a formation constant 9.1 x 108 and pK 13.0.

Schiff base equilibria. VIII. Aqueous equilibria between salicylaldehyde and aliphatic diamines

1973 ◽  
Vol 26 (8) ◽  
pp. 1653 ◽  
Author(s):  
RW Green ◽  
PW Alexander ◽  
RJ Sleet
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Equilibrium Constants ◽  
Large Excess ◽  
Acid Base ◽  
Aliphatic Diamines

Equilibria between salicylaldehyde and three aliphatic diamines, ethylenediamine, trimethylenediamine, and 1,3-diaminopropan-2-ol, have been measured in aqueous solution containing a large excess of diamine to suppress hydrolysis. Equilibrium constants are reported for the formation and acid-base reactions of the mono-salicylideneimines formed from the three diamines. It is demonstrated that there are no conditions under which detectable concentrations of bis- salicylideneimines exist in aqueous solution.

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.

Polarimetric and nuclear magnetic resonance studies of the complexation of mercury by thiols

1988 ◽  
Vol 66 (12) ◽  
pp. 3184-3189 ◽  
Author(s):  
Mohamed M. Shoukry ◽  
Bruce V. Cheesman ◽  
Dallas L. Rabenstein
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Formation Constant ◽  
Ph Dependence ◽  
Equilibrium Constants ◽  
Rotatory Power ◽  
Acid Dissociation ◽  
Optical Rotatory ◽  
Optical Rotatory Power ◽  
Nuclear Magnetic

The complexation of Hg(II) by glutathione has been studied by polarimetry under conditions of excess ligand with the objective of characterizing formation of the 3:1 complex, Hg(glutathione)3. The optical rotatory power of solutions containing glutathione only and of solutions containing glutathione and Hg(II) at ratios of 2:1, 2.5:1, 3:1, and 4:1 was measured as a function of pH. Acid dissociation constants for the ammonium and thiol groups of glutathione and for the two ammonium groups of Hg(glutathione)2 and the formation constant of the 3:1 complex (Hg(glutathione)2 + glutathione [Formula: see text] Hg(glutathione)3) were determined from the pH dependence of the optical rotatory power. The value obtained for the formation constant, Kf = 1.5 × 103, indicates that binding of the third ligand to form Hg(glutathione)3 is much weaker than binding of the first two glutathione ligands. However, calculations indicate that binding is sufficiently strong that a significant fraction of Hg(II) is present as Hg(glutathione)3 under physiological conditions. Equilibrium constants were also determined by polarimetry and by 13C nuclear magnetic resonance for the displacement of one thiolate ligand by another (RSHgSR + R′SH [Formula: see text] RSHgSR′ + RSH; RSHgSR′ + R′SH [Formula: see text] R′SHgSR′ + RSH). The results indicate that, at pH 5.5 and at physiological pH, the relative stability increases in the order Hg(glutathione)2 < Hg(penicillamine)2 < Hg(mercaptoethylamine) 2. However, when competitive protonation of free ligand is accounted for, it is shown that the intrinsic stability of the complexes increases in the order Hg(penicillamine)2 < Hg(mercaptoethylamine)2 < Hg(glutathione)2, which parallels the order of the Brønsted basicity of the thiolate ligands.

Thermochromism of Metal Exchange Reaction between Zinc(II) and Mercury(II) Porphyrins

1995 ◽  
Vol 50 (4) ◽  
pp. 545-550 ◽  
Author(s):  
Masaaki Tabata ◽  
Masahiro Ide ◽  
Kentaro Kaneko
Keyword(s):  
Aqueous Solution ◽  
Exchange Reaction ◽  
Thermodynamic Parameters ◽  
Distribution Curve ◽  
Equilibrium Constants ◽  
Metal Exchange ◽  
Free Base ◽  
Temperature Range ◽  
Base Form ◽  
Metal Exchange Reaction

Thermochromism was observed for an aqueous solution containing zinc(II) and mercury( II) cations and N-p-nitrobenzyl-5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin anion (NO2Bz(Htpps)4-) in the temperature range 10 to 70 °C. The equilibrium constants and the thermodynamic parameters of Zn(NO2Bztpps)3- and Hg(NO2Bztpps)3- have been determined spectrophotometrically to elucidate the thermochromism at 10, 15, 20, 25 and 30 °C in 0.1 mol dm-3 NaNO3. The protonation and metalation constants of NO2Bz(Htpps)4- are defined as K2 = [H2P][H+]-1[HP]-1, K3 = [H3P][H+]-1[H2P]-1 and KMP = [M P][H+][M2+]-1[HP]-1, where HP and MP denote the free base form of the prophyrin and the metalloporphyrins of zinc(II) and mercury(II), respectively. Charges of the prophyrin and metalloporphyrins are omitted for simplicity. The following values were found: logK2 = 7.75 ±0.02 (25 °C), ΔH°/kJmol-1 = -21.2±0.5 and ΔS°/Jmol-1K-1 = 77±1, logK3 = 2.55±0.02 (25 °C), ΔH°/kJmol-1 = -25±0.8 and ΔS°/Jmol-1K-1 = -35±3 and log KZnP = 0.63±0.03 (25 °C), ΔH°/kJmol-1 = 31.0±0.8 and ΔS°/Jmol-1K-1 = 116±3, logKHgP = 6.22±0.03 (25 °C), ΔH°/kJmol-1 = 4.5±0.7 and ΔS°/Jmol-1K-1 = 134±2. The distribution curve calculated from the thermodynamic parameters sufficiently agrees with the observed metal exchange reaction between the metalloporphyrins.

Schiff base equilibria. I. Formation and distribution of N-n-butylsalicylideneimine

1965 ◽  
Vol 18 (3) ◽  
pp. 329 ◽  
Author(s):  
RW Green ◽  
PW Alexander
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Distribution Coefficient ◽  
Equilibrium Constant ◽  
Neutral Form ◽  
Phenolic Group

The equilibrium constant governing the formation of a Schiff base from salicylaldehyde and n-butylamine in aqueous solution has been evaluated by spectrophotometry as 5.62 x 104. The pK of the phenolic group of the Schiff base is 12.0. These constants have been used to account for the distribution of salicylaldehyde between water and toluene in the presence of butylamine. The neutral form of the Schiff base has a distribution coefficient of 1.9 x 103.

A fluorescent colorimetric azo dye based chemosensor for detection of S2− in perfect aqueous solution and its application in real sample analysis and building a molecular logic gate

2018 ◽  
Vol 10 (20) ◽  
pp. 2317-2326 ◽  
Author(s):  
Amit Kumar Manna ◽  
Jahangir Mondal ◽  
Rukmani Chandra ◽  
Kalyani Rout ◽  
Goutam Kumar Patra
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Azo Dye ◽  
Color Change ◽  
Logic Gate ◽  
Real Sample ◽  
Sample Analysis ◽  
Real Sample Analysis ◽  
Molecular Logic Gate ◽  
Molecular Logic

A fluorescent-colorimetric azo dye based bis-Schiff base chemosensor, L, has been developed. L can selectively detect S2− through a color change from yellow to orange in perfect aqueous solution by deprotonation mechanism.

scholarly journals A fluorescent pH probe for an aqueous solution composed of 7-hydroxycoumarin, Schiff base and phenanthro[9,10-d]imidazole moieties (PICO)

2018 ◽  
Vol 24 (2) ◽  
pp. 93-97
Author(s):  
Shaoxin Li ◽  
Wei Kan ◽  
Bing Zhao ◽  
Ting Liu ◽  
Yue Fang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Fluorescent Probe ◽  
Fluorescence Intensity ◽  
Ph Probe ◽  
Pka Value

AbstractThe pH fluorescent probe 7-hydroxy-4-methyl-8-(((2-(1-phenyl-1H-phenanthro[9,10-d]imidazol-2-yl)phenyl)imino)methyl)-2H-chromen-2-one (PICO) contains a donor–π–acceptor (D–π–A) conjugated system. The ‘off−on’ probe PICO has a pKa value of 8.01 and its fluorescence intensity is enhanced with increasing pH.

A turn-on Schiff base fluorescent probe for the exogenous and endogenous Fe3+ ion sensing and bioimaging of living cells

2020 ◽  
Vol 44 (45) ◽  
pp. 19642-19649
Author(s):  
Lingjie Hou ◽  
Tao Liu ◽  
Yaling Gong ◽  
Jin Li ◽  
Chenhua Deng ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Fluorescent Probe ◽  
Living Cells ◽  
Naphthalic Anhydride ◽  
Turn On ◽  
Ion Sensing

A Schiff base fluorescent probe, namely naphthalic anhydride – (2-pyridine) hydrazone (NAH), has been synthesized and developed for the highly selective and sensitive monitoring of Fe3+ ions in an aqueous solution and living cells.

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