Thermodynamic behavior of complexation of 18-crown-6 with Tl+, Pb2+, Hg2+, and Zn2+ metal cations in methanol-water binary media

Rounaghi, Gholam Hossein; Zavvar, Mohammad Hossein Arbab; Badiee, K.

doi:10.1134/s003602360804030x

Cited by 2 publications

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“…As shown in Figure 8, straight lines with two breaks of the [L]/[M] ratio of 1 and 2 indicate the formation of 1:1 and 1:2 (M:L) stoichiometric complexes between the metal ion and the ligand under investigation. [26][27][28][29] These results agree with that obtained from the pH-metric study.…”

Section: Conductometric Studysupporting

confidence: 86%

“…Many conductometric studies , have been used to decide the formation of different stoichiometric complexes in aqueous and nonaqueous solutions. The method of conductometric measurements was carried out at 298.15 K in water in 5 % (v/v) ethanol−water solvents as explained earlier where 0.001 mol·dm −3 solution of the ligand was added to a 10 mL (0.0001 mol·dm −3 ) solution of the metal cation.…”

Section: Conductometric Studymentioning

confidence: 99%

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Hydroxycoumarine Azodye, Thermal Stability, Harmonic Vibrational Spectra, Conductance, and pH Measurements

2009

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Two metal complexes resulting from reaction of hydroxycoumarine azodye with Zn(II) and Cd(II) have been synthesized and characterized using elemental analyses, thermal analyses (TGA and DTG), IR, and conductance measurements. The results show that the ligand coordinates to Zn(II) and Cd(II) as a neutral bidentate through the carbonyl oxygen and the azo nitrogen. Semiempirical calculations using PM3 and ZINDO/1 have been employed to study the harmonic vibrational spectra of the ligand and its metal complexes with the purpose to assist in the experimental assignments of the bands. The thermodynamic parameters E, ∆H, ∆G, and ∆S have been calculated from the thermal analysis curves (TGA and DTG) using the Coats-Redfern, Horowitz-Metzger, and Freeman-Carroll methods. The dissociation constant of the ligand has been determined pH-metrically in 0.1 mol • dm -3 KCl at 298.15 K. Conductometric titrations showed that all the investigated metal ions have 1:1 and 1:2 (M:L) stoichiometric ratios.

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Section: Conductometric Studysupporting

confidence: 86%

Section: Conductometric Studymentioning

confidence: 99%