Publication: L-Sistein - kreatinin’in ve L-sistein.HCl (BDHL-sistein) - kreatinin’in Co(II), Cd(II), Zn(II), Mn(II) ile Karışık Komplekslerinin Kararlılık Sabitlerinin Potansiyometrik Yöntemle Tayini
Abstract
Bu çalışmada kreatinin ve iki aminoasit'in Co(II), Cd(II), Zn(II), Mn(II) ile oluşturduğu karışık komplekslerin kararlılık sabitleri potansiyometrik titrasyon yöntemi ile tayin edilmiştir. Üçlü komplekslerin stabilite sabitleri Irving Rossotti yöntemi ile 25ºC de ve iyonik kuvvet NaClO4 ile sabit tutularak (0.11M) sulu çözeltide incelenmiştir. Ayrıca oluşan komplekslerin koşullu oluşum sabitleri pH'a bağlı olarak hesaplanmış ve belirli bir pH bölgesinde koşullu oluşum sabitinin maksimum olduğu değerin deneysel olarak bulunan kararlılık sabiti ile uyum içinde olduğu gözlenmiştir. Hesaplanan koşullu oluşum sabitlerinden yararlanılarak karışık kompleksten türeyen çeşitli türlerin bağıl bollukları incelenmiştir. İyonik kuvvet NaClO4 ile I=0.11 de sabit tutulmuştur. 250C da L-sistein ve kreatinin'in metal komplekslerinin kararlılık sabitleri: Zn(II)-L-sistein-kreatinin için logK=3.20, Co(II)-L-sistein-kreatininiçin logK=4.24 ve logK2=3.58, Cd(II)-L-sistein-kreatinin için logK=3.22, Mn(II)-L-sistein-kreatinin içinlogK=3.65 ve Co(II)-BDHL-sistein-kreatinin için logK=5.34, Cd(II)-BDHL-sistein-kreatinin içinlogK=5.30, Zn(II)BDHL-sistein-kreatinin2 için logK1=5.35 ve logK2=3.93, Mn(II)-BDHL-sistein- kreatinin2 için logK1=5.40 ve log K2=3.49 olarak hesaplanmıştır
In this study, a potentiometric titration technique has been used to determine stability constants for the various complexes of Zn(II), Co(II), Cd(II) and Mn(II) with creatinine and two amino acids. Stability constants of ternary systems have been evaluated by the method suggested by Irving-Rossotti at 25ºC and 0.11M ionic strength (kept constant with NaClO4 ) in aqueous solution. In addition, the conditional constants were calculated as a function of pH. The maximum values of the conditional formation constants were found to be in accordance with the mixed-ligand complex formation constants in a given pH region. In addition, the mole fractions of different species from mixed complexes were calculated by means of formation constants. The values of stability constants of mixed-ligand complexes at 25ºC were calculated as follows: logK=3.20 for Zn(II)-L-cysteine-creatinine,logK1 =4.24 and logK2 =3.58 for Co(II)-L-cysteinecreatinine2 , logK=3.22 for Cd(II) - L-cysteine – creatinine, logK=3.65 for Mn(II) - L-cysteine – creatinine and logK=5.34 for Co(II)-BDHL-cysteine-creatinine, logK=5.30 for Cd(II)-BDHL-cysteine-creatinine, logK1 =5.35 and logK2 =3.93 for Zn(II) - BDHL-cysteine - creatinine2 , logK1 =5.40 and logK2 =3.49 for Mn(II) - BDHL-cysteine - creatinine2.
In this study, a potentiometric titration technique has been used to determine stability constants for the various complexes of Zn(II), Co(II), Cd(II) and Mn(II) with creatinine and two amino acids. Stability constants of ternary systems have been evaluated by the method suggested by Irving-Rossotti at 25ºC and 0.11M ionic strength (kept constant with NaClO4 ) in aqueous solution. In addition, the conditional constants were calculated as a function of pH. The maximum values of the conditional formation constants were found to be in accordance with the mixed-ligand complex formation constants in a given pH region. In addition, the mole fractions of different species from mixed complexes were calculated by means of formation constants. The values of stability constants of mixed-ligand complexes at 25ºC were calculated as follows: logK=3.20 for Zn(II)-L-cysteine-creatinine,logK1 =4.24 and logK2 =3.58 for Co(II)-L-cysteinecreatinine2 , logK=3.22 for Cd(II) - L-cysteine – creatinine, logK=3.65 for Mn(II) - L-cysteine – creatinine and logK=5.34 for Co(II)-BDHL-cysteine-creatinine, logK=5.30 for Cd(II)-BDHL-cysteine-creatinine, logK1 =5.35 and logK2 =3.93 for Zn(II) - BDHL-cysteine - creatinine2 , logK1 =5.40 and logK2 =3.49 for Mn(II) - BDHL-cysteine - creatinine2.