A potentiometric study on the complexes of His,Gly-His,ALa-His,Gly-Gly and Gly—Gly—Gly with Zn(Ⅱ)and Cd(Ⅱ)has been reported.Small-scale potentiometric titrations were car- ried out to determine stabil ity constant...A potentiometric study on the complexes of His,Gly-His,ALa-His,Gly-Gly and Gly—Gly—Gly with Zn(Ⅱ)and Cd(Ⅱ)has been reported.Small-scale potentiometric titrations were car- ried out to determine stabil ity constants of complexes at 25℃ with I=0.10 mol dm^(-3)(KNO_3).The com- puter programs SUPERQUAD were applied for data treatment with satisfactory results.展开更多
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
The acid dissociation constants of N-carboxymethyl-N-(p-hydroxy phenyl carbamoyl- methyl)-2,3-dihydroxy-5-carbomethoxy benzylamine(CHDCB) and the stability constants of its 1:1 complexes with alkaline earth, Cd(Ⅱ), ...The acid dissociation constants of N-carboxymethyl-N-(p-hydroxy phenyl carbamoyl- methyl)-2,3-dihydroxy-5-carbomethoxy benzylamine(CHDCB) and the stability constants of its 1:1 complexes with alkaline earth, Cd(Ⅱ), Co(Ⅱ), Ni(Ⅱ), Cu(Ⅱ), Zn(Ⅱ), Fe(Ⅲ),Th(Ⅳ)and U(Ⅵ)ions have been determined at 25.0±0.1℃ and at an ionic strength of 0.1(KNO_3)by pH titration method. The probable coordination sites have also been discussed.展开更多
文摘A potentiometric study on the complexes of His,Gly-His,ALa-His,Gly-Gly and Gly—Gly—Gly with Zn(Ⅱ)and Cd(Ⅱ)has been reported.Small-scale potentiometric titrations were car- ried out to determine stabil ity constants of complexes at 25℃ with I=0.10 mol dm^(-3)(KNO_3).The com- puter programs SUPERQUAD were applied for data treatment with satisfactory results.
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The acid dissociation constants of N-carboxymethyl-N-(p-hydroxy phenyl carbamoyl- methyl)-2,3-dihydroxy-5-carbomethoxy benzylamine(CHDCB) and the stability constants of its 1:1 complexes with alkaline earth, Cd(Ⅱ), Co(Ⅱ), Ni(Ⅱ), Cu(Ⅱ), Zn(Ⅱ), Fe(Ⅲ),Th(Ⅳ)and U(Ⅵ)ions have been determined at 25.0±0.1℃ and at an ionic strength of 0.1(KNO_3)by pH titration method. The probable coordination sites have also been discussed.
