Characterization by Potentiometric Procedures of the Stability Constants of the Binary and Ternary Complexes of Cu(II) and Duloxetine Drug with Amino Acids
Table 3
Formation coefficients of ternary complexes in Cu(II)-D-amino acids systems at 25°C and 0.10 mol·L−1 ionic strength.
System
l
p
q
r
log10βa
%R.S.b
Cu(II)-D-Gly
1
1
1
0
17.32 (0.01)
9.25
9.17
1.1
13.50
Cu(II)-D-Ala
1
1
1
0
17.12 (0.02)
8.95
8.89
0.82
10.09
Cu(II)-D-Val
1
1
1
0
17.05 (0.01)
8.98
8.94
0.87
10.73
Cu(II)-D-Pro
1
1
1
0
17.61 (0.01)
9.54
9.01
0.04
10.93
Cu(II)-D-Phe
1
1
1
0
16.75 (0.02)
8.68
8.40
0.33
3.95
Cu(II)-D-Met
1
1
1
0
17.96 (0.02)
9.89
9.86
1.79
22.10
Cu(II)-D-Thr
1
1
1
0
17.56 (0.02)
9.49
9.22
1.15
13.64
1
1
1
−1
2.62 (0.02)
Cu(II)-D-Orn
1
1
1
0
20.30 (0.01)
12.23
8.45
0.38
3.21
1
1
1
1
25.45 (0.01)
Cu(II)-D-Lys
1
1
1
0
20.76 (0.03)
12.69
8.93
0.86
7.27
1
1
1
1
24.88 (0.01)
Cu(II)-D-Hisd
1
1
1
0
21.30 (0.01)
13.23
10.55
2.58
24.22
1
1
1
1
26.01 (0.01)
Cu(II)-D-Hist
1
1
1
0
20.90 (0.04)
12.83
11.51
3.44
36.63
1
1
1
1
25.11 (0.02)
Cu(II)-D-Imz
1
1
1
0
13.34 (0.002)
5.27
9.11
1.04
24.59
Note: l, p, q, and r represent stoichiometric constants corresponding to Cu(II), D, amino acids, and H+, respectively. aStandard deviation is presented in parentheses. bPercentage of the relative stabilization value, and coefficient −1 designates proton loss.
