Salicylic Acid Derivatives Form Stable Complexes with Scandium(III) Ion in Aqueous Solution.

CHEMICAL & PHARMACEUTICAL BULLETIN

et al. 2005

We continue our studies on the complex equilibria between Cr(III), Sc(III), Y(III) and 1-hydroxy-2-naphthoic acid (1,2-HNA: H 2 L) and 3-hydroxy-2-naphthoic acid (3,2-HNA: H 2 L). We have reported the stabilities of the complexes between these metal ions and the title ligands. [1][2][3][4][5][6][7][8][9][10][11] The structural formulas of the studied ligands are shown in Fig. 1. There have been some reports on the Sc(III) and Y(III) complexes of hydroxy naphthoic acids [12][13][14][15] ; but almost nothing is known about the complexes between Cr(III) and these two naphthoic acids. However, the stabilities and stoichiometries of the complexes formed with Cr(III), Sc(III), Y(III) and hydroxy benzoic acids were already determined by us. [4][5][6][7][8][9][10][11] It is well known that the derivatives of naphthoic acids are used as dyes and reagents for spectrophotometric measurements since they form chelates with several metal ions, whereas hydroxy carboxylic acids of the naphthalene series are far less common as ligands for complexometric studies than hydroxy benzoic acids. Some reports on binary complex formation abilities are available in the literature for various metal ions. [12][13][14][15][16][17][18][19][20][21] Currently our main aim is to investigate the binding abilities of 1,2-HNA and 3,2-HNA to Cr(III), Sc(III) and Y(III) and to determine the formation constants of their complexes.On the other hand, the humic substances are derivatives of hydroxy naphthoic and hydroxy benzoic acids and they are found in natural ligands. They can remove environmentally mobile ions like Cu(II), Fe(III) and Al(III) that originate from various industries since humic substances are easily coordinated from oxygen donor sites to these metal ions and form very stable chelates. [22][23][24][25][26][27] Cr(III), with Cr(VI), is one of the main pollutant during waste water treatment in our city, Bursa. 28) So, the removal of Cr(III) from waste water may be possible using 1,2-HNA and 3,2-HNA ligands. Therefore, our second aim is to determine the concentration of uncomplexed Cr(III) by means of the formation constants of its 1,2-HNA and 3,2-HNA complexes as a part of our research project.However, Bhatt et al. 12,13) were interested in the complex formation reactions of Sc(III) with 1,2-HNA and 3,2-HNA but they were mainly ternary complex forming systems. They obtained the stability constants of binary complexes of Sc(III) with 1,2-HNA and 3,2-HNA only at an ionic strength of 0.1 M KNO 3 in 50% (v/v) aqueous-ethanol medium by the average value method. 29,30) Y(III) and lanthanides formed with 2-hydroxy-3-naphthoic acid (2,3-HNA), 2-hydroxy-1-naphthoic acid (2,1-HNA) and 1,2-HNA were also investigated by Bhatt et al. 14) and Deshpande et al. 15) They applied only the Calvin-Bjerrum potentiometric titration technique at 25°C and 0.1 M NaClO 4 ionic strength in 75% dioxane-25% (v/v) water medium. Neither Bhatt et al. [12][13][14] nor Deshpande et al. 15) had taken into consideration the stoichiometries of Sc(III) and Y(III) complexe...

Section: Resultssupporting

confidence: 49%

mentioning

confidence: 99%

Formation Constants of Chromium(III), Scandium(III) and Yttrium(III) Complexes of Some Hydroxy Naphthoic Acids

Aksoy

Aydın

CHEMICAL & PHARMACEUTICAL BULLETIN

et al. 2005

“…The results of those previous studies suggested that Sc(III) ion forms the most stable complexes in binary ligand system in aqueous solution. The complexes of Sc(III), Y(III), and La(III) formed in different ionic mediums have been the most adequate complexes to identify the coordination number and the structure of these complexes [4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Study of Metal-1,10-Phenanthroline Complex Equilibria by Potentiometric Measurements

ISRN Analytical Chemistry

2012

The interaction of Sc(III), Y(III), and La(III) ions with 1,10-phenanthroline (Phen) has been investigated, using the potentiometric method at 25 ± 0.1• C and I = 0.10 M KNO 3 . Collected potentiometric data were processed by the "BEST" software program to establish the complexation model for each system. SPE software program was used to evaluate the concentration distributions of the species formed in solution. The stability constants for the binary complexes increased as the ionic radii of the metal cations decreased.

“…The main species in aqueous solutions of Sc(III) and the related equilibrium constants of the hydroxo complexes were also reviewed [3,4]. The preferences of Sc(III) towards catechol, salicylic acid, and their derivatives were investigated in [5][6][7]. It is known that the hydrolytic tendency of Sc 3+ ion decreases with increasing number of binding sites of phenolates and/or carboxylate donors.…”

Section: Introductionmentioning

confidence: 99%

Potentiometric investigations of some catechol derivatives of scandium

Özer

2005

Russ J Coord Chem

The equilibrium reactions of scandium(III) with some triprotic catechol derivatives (H 3 L) were studied. The selected ligands that are 2,3-dihydroxybenzoic acid (2,3-DHBA), 3,4-dihydroxybenzoic acid (3,4-DHBA), 3.4-dihydroxyhydrocinnamic acid (3,4-DHHCA), and 3,4-dihydroxyphenylacetic acid (3,4-DHPA) were investigated in aqueous solution by means of potentiometry in 0.1 M ionic medium at 25 ° C. The stability constants are reported for the ScL and ScL ( H 2 L ) -mononuclear complexes. 2,3-DHBA can bind to Sc 3+ ion strongly and the salicylate mode (COO -, O -) is effective over the acidic pH range. But in higher pH range, 3,4-DHBA, 3,4-DHHCA, and 3,4-DHPA act more efficiently through catecholate groups (O -, O -).