This paper reports the determination of stability constants for complexes of Cd(Ⅱ)with Gly, Ala,Val,Asp,Gly—Asp,Asp Gly,Gly—Gly and Gly—Gly—Gly using both micro—pH—metric titra- tions and the application of con...This paper reports the determination of stability constants for complexes of Cd(Ⅱ)with Gly, Ala,Val,Asp,Gly—Asp,Asp Gly,Gly—Gly and Gly—Gly—Gly using both micro—pH—metric titra- tions and the application of convolution—deconvolution cyclic voltammetry at 25℃ and I=0.10 mol· dm^(-3)(KNO_3).Stability constants were calculated from pH—metric data using the SUPERQUAD com- puter program and cyclic voltammograms were collected,stored and manipulated using the EG and G CONDECON 300 software.A considerably larger ligand:metal ratio(e,g.50:1)was possible using voltammetry.Evaluation of results from the two techniques suggests that stability constants for the species[CdL_2]and[CdL_3]are reliable when calculated fromvoltammetry while those for[CdL]are more reliable when determined by pH-metric titration.展开更多
This paper reports the determination of stability constants for complexes of Pb(Ⅱ) with Gly, Ala, Asp and Gly-Gly using both micro-pH-metric titrations and the application of convolution-de- convolution cyclic voltam...This paper reports the determination of stability constants for complexes of Pb(Ⅱ) with Gly, Ala, Asp and Gly-Gly using both micro-pH-metric titrations and the application of convolution-de- convolution cyclic voltammetry at 25℃ and I = 0.10 mol.dm^(-3)(KNO_3). Stability constants were calculated from pH-metric data using the SUPERQUAD computer program and cyclic voltammograms were collected, stored and manipulated using the E G and G CONDECON 300 software. A consider- ably larger ligand: metal ratio (e.g. 50:1) was possible using voltammetry. Under these conditions, hydroxy complex formation was minimised and the formation of bis-complexes optimised. Computer based calculations were carried out on PC-compatible microcomputers fitted with mathematics co- processors. Evaluation of results from the two techniques suggests that stability constants for the species [PbL_2] are reliable when calculated from voltammetry while those for [PbL] are mote reliable when determined by pH-metric titration.展开更多
To study the coordination reactions of glucosamine and α-aminoacid with copper(Ⅱ) under the physiological condition,the pH potentiometric titration was used to determine the protonation constants of glucosamine and ...To study the coordination reactions of glucosamine and α-aminoacid with copper(Ⅱ) under the physiological condition,the pH potentiometric titration was used to determine the protonation constants of glucosamine and α-aminoacid,and the formation constants of the binary and ternary complexes of glucosamine and α-aminoacid with Cu(Ⅱ) at 37℃ with ionic strength I=0.154mol/L NaCl respectively.The results indicated that all of the protonation constants of glucosamine and α-aminoacid,and stability constant of the binary and ternary complexes of glucosamine and α-aminoacid with Cu(Ⅱ) at 37℃,I=0.154mol/L NaCl are smaller than those at 25℃ with ionic strength I=0.10 mol/L KNO3 respectively.The results also indicated that the stable ternary complex could be formed from glucosamine and α-aminoacid with copper(Ⅱ).Furthermore,the two biologically active ligand,glucosamine and α-aminoacid showed higher compatible.The stability of the ternary complexes increased with the increase of protonation constant of α-aminoacid and the stability of its binary complexes.展开更多
文摘This paper reports the determination of stability constants for complexes of Cd(Ⅱ)with Gly, Ala,Val,Asp,Gly—Asp,Asp Gly,Gly—Gly and Gly—Gly—Gly using both micro—pH—metric titra- tions and the application of convolution—deconvolution cyclic voltammetry at 25℃ and I=0.10 mol· dm^(-3)(KNO_3).Stability constants were calculated from pH—metric data using the SUPERQUAD com- puter program and cyclic voltammograms were collected,stored and manipulated using the EG and G CONDECON 300 software.A considerably larger ligand:metal ratio(e,g.50:1)was possible using voltammetry.Evaluation of results from the two techniques suggests that stability constants for the species[CdL_2]and[CdL_3]are reliable when calculated fromvoltammetry while those for[CdL]are more reliable when determined by pH-metric titration.
文摘This paper reports the determination of stability constants for complexes of Pb(Ⅱ) with Gly, Ala, Asp and Gly-Gly using both micro-pH-metric titrations and the application of convolution-de- convolution cyclic voltammetry at 25℃ and I = 0.10 mol.dm^(-3)(KNO_3). Stability constants were calculated from pH-metric data using the SUPERQUAD computer program and cyclic voltammograms were collected, stored and manipulated using the E G and G CONDECON 300 software. A consider- ably larger ligand: metal ratio (e.g. 50:1) was possible using voltammetry. Under these conditions, hydroxy complex formation was minimised and the formation of bis-complexes optimised. Computer based calculations were carried out on PC-compatible microcomputers fitted with mathematics co- processors. Evaluation of results from the two techniques suggests that stability constants for the species [PbL_2] are reliable when calculated from voltammetry while those for [PbL] are mote reliable when determined by pH-metric titration.
文摘To study the coordination reactions of glucosamine and α-aminoacid with copper(Ⅱ) under the physiological condition,the pH potentiometric titration was used to determine the protonation constants of glucosamine and α-aminoacid,and the formation constants of the binary and ternary complexes of glucosamine and α-aminoacid with Cu(Ⅱ) at 37℃ with ionic strength I=0.154mol/L NaCl respectively.The results indicated that all of the protonation constants of glucosamine and α-aminoacid,and stability constant of the binary and ternary complexes of glucosamine and α-aminoacid with Cu(Ⅱ) at 37℃,I=0.154mol/L NaCl are smaller than those at 25℃ with ionic strength I=0.10 mol/L KNO3 respectively.The results also indicated that the stable ternary complex could be formed from glucosamine and α-aminoacid with copper(Ⅱ).Furthermore,the two biologically active ligand,glucosamine and α-aminoacid showed higher compatible.The stability of the ternary complexes increased with the increase of protonation constant of α-aminoacid and the stability of its binary complexes.
