scholarly journals INVESTIGATION OD ACID-BASE PROPERTIES OF AROMATIC HYDRAZONES IN BASIC MEDIA AT CONSTANT IONIC STRENGTH

2017 ◽  
Author(s):  
Mirjana S. Jankulovska ◽  
Vesna Dimova ◽  
Ilinka Spirevska
2012 ◽  
Vol 314 ◽  
pp. 185-197 ◽  
Author(s):  
Clemente Bretti ◽  
Francesco Crea ◽  
Concetta De Stefano ◽  
Silvio Sammartano ◽  
Giuseppina Vianelli

2017 ◽  
Vol 21 (09) ◽  
pp. 611-621
Author(s):  
Hirofumi Konno ◽  
Jun Takeda

The synthesis, acid-base properties, and kinetics of Cu[Formula: see text] incorporation into water-soluble highly substituted porphyrins were studied. The basicity increased and the stepwise acid-base equilibrium was clarified by increasing the number of phenyl groups at the [Formula: see text] position, and the basicity of a dodeca-substituted porphyrin increased with the ionic strength. The metalation reaction of the dodeca-substituted porphyrin with Cu[Formula: see text] in aqueous solution revealed a biphasic absorbance change at 453 nm. Plots of [Formula: see text] or[Formula: see text] vs. the Cu[Formula: see text] concentration and of log ([Formula: see text] or[Formula: see text]/[Formula: see text] 0) vs. the ionic strength show that [Formula: see text] is dependent on the Cu[Formula: see text] concentration and ionic strength, while [Formula: see text] is independent of these parameters. These results confirm the stepwise metalation mechanism and the existence of an intermediate in aqueous solution, which is indicated by the biphasic absorbance change at 453 nm.


2018 ◽  
Vol 483 ◽  
pp. 191-200 ◽  
Author(s):  
Yuxia Liu ◽  
Daniel S. Alessi ◽  
Shannon L. Flynn ◽  
Md. Samrat Alam ◽  
Weiduo Hao ◽  
...  

2015 ◽  
Vol 90 ◽  
pp. 51-58 ◽  
Author(s):  
Clemente Bretti ◽  
Rosalia Maria Cigala ◽  
Concetta De Stefano ◽  
Gabriele Lando ◽  
Demetrio Milea ◽  
...  

2009 ◽  
Vol 74 (3) ◽  
pp. 269-277 ◽  
Author(s):  
Branka Drazic ◽  
Gordana Popovic ◽  
Ratomir Jelic ◽  
Dusan Sladic ◽  
Dragana Mitic ◽  
...  

Acid-base equilibria of Zn(II) and Fe(III) complexes with N',N'2-bis- [(1E)-1-(2-pyridyl)ethylidene]ethanedihydrazide (ligand L1) and N',N'2-bis[(1E)- -1-(2-pyridyl)ethylidene]propanedihydrazide (ligand L2), i.e., [Fe(L1)Cl2(H2O)], [Fe(L2)Cl(H2O)]2+, [Zn(L1)(H2O)3]+ and [Zn(L2)(H2O)2]2+, which expressed cytotoxic activity, were investigated in aqueous media. The equilibrium constants were determined potentiometrically at 25?C at a constant ionic strength of 0.10 mol/dm3 (Na2SO4). The results showed that at pH < 8 both the Fe(III) complexes studied here have three, while [Zn(L1)(H2O)3]+ and [Zn(L2)(H2O)2]2+ have one and two titratable protons, respectively. Based on the obtained values for the equilibrium constants, protonation schemes of the examined complexes are proposed.


1998 ◽  
Vol 63 (1) ◽  
pp. 31-41
Author(s):  
Maria Turowska ◽  
Grzegorz Mloston ◽  
Pawel Krzyczmonik ◽  
Jacek Raczak ◽  
Jaroslaw Romanski

The dissociation constants Ka for spherically crowded 2'- and 2,5-substituted thiadiazolines and their protonated forms in 45% (v/v) aqueous-ethanolic solutions (ionic strength m = 0.1) were determined using the pH-metric method. All the thiadiazoles are weak bases. Some of them showed also weak acidic properties. The formation enthalpies have been calculated using the MNDO method. On the basis of the obtained results the mechanism of the protonation process is discussed.


1988 ◽  
Vol 85 ◽  
pp. 523-527
Author(s):  
M.M. Zuleika ◽  
Palhares SILVA ◽  
Ernesto Rafael GONZALEZ ◽  
Luis Alberto AVACA ◽  
Artur de Jesus MOTHEO

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