TY - JOUR
T1 - Graphic data analysis and complex formation curves as modeling and optimization tools for characterization of Cu-(buffer)x-(OH) y systems involving BTP or BES in aqueous solution
AU - Sadeghi, S. Maryam
AU - Ferreira, Carlos M. H.
AU - Vandenbogaerde, Sarah
AU - Soares, Helena M. V. M.
N1 - Funding Information:
This work was financed by FEDER funds through Programa Operacional Factores de Competitividade – COMPETE and by National Funds through FCT – Fundação para a Ciência e a Tecnologia in the ambit of the project Pest-C/EQB/LA0006/2013. The authors thank Professor Ignacy Cukrowski from the University of Pretoria (South Africa) for polarographic modeling software (3D-CFC program) and Professor Carlos Gomes from the Faculty of Sciences/Porto University for the COPOTISY program.
Publisher Copyright:
© 2015 Taylor & Francis.
PY - 2015/3/4
Y1 - 2015/3/4
N2 - Bis-tris propane or 1,3-bis(tris(hydroxymethyl)methylamino)propane (BTP) and N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES) are pH buffers which have been used in biological experiments. To characterize BTP and BES complexation properties with Cu(II), glass electrode potentiometry and direct current polarography were conducted using total ligand to total copper concentration ratios of different orders of magnitude and pH values at 25 °C and 0.1 M KNO3 ionic strength. The graphic analysis is a very powerful tool in the prediction and refinement operations of both systems. For the Cu-BTP system, six species were found to describe totally the system, CuL, CuL(OH), CuL(OH)2, CuL2, CuL2(OH), and CuL2(OH)2, with respective stability constants determined as 10.7 ± 0.1, 19.4 ± 0.4, 24.3 ± 0.2, 18.8 ± 0.1, 24.7 ± 0.2, and 29.8 ± 0.2. CuL2, CuL2(OH), and CuL2(OH)2 were described for the first time. In the case of the Cu-BES system, complexation behavior was described by the model constituted by CuL, CuL(OH), and CuL(OH)2, the latter two described for the first time, with respective stability constants determined as 3.24 ± 0.08, 10.9 ± 0.2, and 16.0 ± 0.3, respectively. UV-vis results allowed us to establish coordination modes for the Cu-BTP and Cu-BES complexes.
AB - Bis-tris propane or 1,3-bis(tris(hydroxymethyl)methylamino)propane (BTP) and N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES) are pH buffers which have been used in biological experiments. To characterize BTP and BES complexation properties with Cu(II), glass electrode potentiometry and direct current polarography were conducted using total ligand to total copper concentration ratios of different orders of magnitude and pH values at 25 °C and 0.1 M KNO3 ionic strength. The graphic analysis is a very powerful tool in the prediction and refinement operations of both systems. For the Cu-BTP system, six species were found to describe totally the system, CuL, CuL(OH), CuL(OH)2, CuL2, CuL2(OH), and CuL2(OH)2, with respective stability constants determined as 10.7 ± 0.1, 19.4 ± 0.4, 24.3 ± 0.2, 18.8 ± 0.1, 24.7 ± 0.2, and 29.8 ± 0.2. CuL2, CuL2(OH), and CuL2(OH)2 were described for the first time. In the case of the Cu-BES system, complexation behavior was described by the model constituted by CuL, CuL(OH), and CuL(OH)2, the latter two described for the first time, with respective stability constants determined as 3.24 ± 0.08, 10.9 ± 0.2, and 16.0 ± 0.3, respectively. UV-vis results allowed us to establish coordination modes for the Cu-BTP and Cu-BES complexes.
KW - Biological buffer
KW - Metal speciation
KW - Polarography
KW - Potentiometry
KW - Stability constants
UR - http://www.scopus.com/inward/record.url?scp=84941138564&partnerID=8YFLogxK
U2 - 10.1080/00958972.2014.1000317
DO - 10.1080/00958972.2014.1000317
M3 - Article
AN - SCOPUS:84941138564
SN - 0095-8972
VL - 68
SP - 777
EP - 793
JO - Journal of Coordination Chemistry
JF - Journal of Coordination Chemistry
IS - 5
ER -