Calorimetric Titration of Selected Divalent Transition Metal Cations with a Novel Macrocyclic Diamide
Aliha T. Amilasan1,2, Jose S. Solis2, Susan D. Arco2,
and Emily V. Castriciones2
1Chemistry Department, College of Science and Mathematics,
Western Mindanao State University, Zamboanga City 7000, Philippines
2Institute of Chemistry, College of Science, University of the Philippines,
Diliman, Quezon City 1101, Philippines
corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.
ABSTRACT
Complex stability constant (β) and thermodynamic parameters ∆H, ∆G, and ∆S as changes in enthalpy, Gibbs free energy and entropy, respectively were determined in methanol at 25 oC for the observed stoichiometric 1:1 complexation of a novel macrocyclic diamide, 1 with selected nitrate salts of divalent transition metal cations (Co(II), Ni(II), Cu(II), and Zn(II)) using isothermal titration calorimetry. Compound 1 was more stable and selective toward Co(II) cation over other divalent cations which was revealed by favorable ∆G (-33.68 kJ/mol) and ∆S (20 J/mol.K) upon complexation in methanol. The preference of 1 for Co(II) was probably due to the favorable desolvations of Co(II) and 1 and conformational changes in methanol. Thermodynamically, complexation of Co(II) and Zn(II) with 1 was driven by enthalpy effect, Ni(II) and Cu(II) complexes were compensated by enthalpy-entropy effect, and 1 selectivity for Co(II) was governed by free Gibbs energy and entropy contribution in methanol.
INTRODUCTION
Macrocyclic diamides are recently recognized as important ligands in which nitrogen donor atoms are incorporated for binding with metal cation guest (Shamsipur et al. 2001; Pearson 1963). These compounds have been successfully used as ionophores in the development of ion selective electrodes (Shamsipur et al. 2002), as extraction or complexation agents of picrate containing cation from aqueous to organic media (Kimura et al. 1998), and as catalysts in the reduction of ketones to their corresponding alcohols (Fonseca & König 2003). . . . .
REFERENCES
ARNAUD-NEU F et al. 2003. Pure and Applied Chemistry 75(1): 71-102.
BUSCHMANN HJ et al. 1998. Journal of Solution Chemistry 27 (2): 135-140.
FONSECA MH, KÖNIG B. 2003. Advance Synthesis and Catalysis 345: 1173-85.
FRÜH P et al. 1979. In: “Coordination Chemistry of Macrocyclic Compounds”. Melson GA Ed. Plenum New York Press: p. 145-217.
GHERROU A et al. 2005. Thermochimica Acta 425: 1-5.
IZATT RM et al. 1976. Journal of American Chemical Society 98(24): 7626-30.
JELESAROV I, BOSSHARD HR. 1999. Journal of Molecular Recognition 12: 3-18.
KIMURA S et al. 1998. Tetrahedron 54: 5575-86.
LAMB J et al. 1980. Journal of American Chemical Society 102(2): 479-482.
LIU Y et al. 1998. Journal of Organic Chemistry 63: 2144-47.
PEARSON R. 1963. Journal of American Chemical Society 85(32): 3533-39.
SHAMSIPUR M et al. 2002 Talanta 58: 237-246.
SHAMSIPUR M et al. 2002. Polish Journal of Chemistry 76: 1665-71.
SHAMSIPUR M et al. 2002. Bulletin of the Korean Chemical Society 23(1): 53-58.
SHAMSIPUR M et al. 2001. Analytical Sciences 17: 935-938.
SHAMSIPUR M et al. 2001. Analytical Sciences 17: 1049-54.
SHAMSIPUR M et al. 1999. Sensors and Actuators B 59: 30-34.
SHAMSIPUR M et al. 1999. Microchemical Journal 63: 202-210.
SHARGHI H, ESHGHI H. 1995. Tetrahedron 51(3): 913-922.
STÖDEMAN M, WADSÖ I. 1995. Pure and Applied Chemistry 67(7): 1059-68.
