Indium complexes 8-hydroxyquinoline

Polymers containing 8-hydroxyquinoline appear to be selective adsorbents for tungsten in alkaline brines (95). In the presence of tartrate and citrate, quinaldic acid [93-10-7] allows the separation of zinc from gallium and indium (96). Either of these compounds can selectively separate lead and zinc from oxide ores as complexes (97). It is also possible to separate by extraction micro quantities of rhenium(VII), using quinoline in basic solution (98). The... 

Direct. Some radionucHdes are packaged in solution for direct sampling (qv) via a septum and injection into the patient. GalHum-67 is a marker of inflammation, infection, and various tumor types. Its half-life is 78.3 h and it is suppHed as the gallium citrate salt. Indium-111 chloride is suppHed for the labeling of white blood ceUs. The In chloride is mixed with oxine (9-hydroxyquinoline) to form a lipophilic, cationic In oxine complex, which enters the white blood ceU. The complex dissociates within the ceU, and the cationic In " ion is trapped within the ceU, owing to its charge. 

Indium, cadmium and silver can be extracted into chloroform as their 8-hydroxyquinoline complexes, and the pH1/2 values for these metals are 2.1, 6.3 and 8.8 respectively. Plot a graph of theoretical percent extraction against pH over the range 0 to 9 for each metal. Deduce the pH of incipient extraction (0.01%) and complete extraction (99.99%) for each metal, and comment on the feasibility of separating each from the other assuming that all the distribution coefficients are sufficiently high. 

The unavailability of suitable starting materials has hindered work in this area, but the reaction of cyclopentadienylindium(I) in Et20/benzene mixtures with 4,4,4-trifiuoro-l-(thien-2 -yl)butane-l,3-dionate (ttaH) gave the extremely hygroscopic In(tta), and similar derivatives of other bidentate ligands were obtained by this same process.14 The reactions of the analogous In(oxine) (oxine = 8-hydroxyquinoline anion) show that such InL species are easily oxidized to indium(III) complexes (see Section 25.2.4.8). The insolubility of the product in the reaction mixture is presumably an important factor in this method. 

Initial work on radiolabeling of autologous polymorphonuclear leukocytes was performed by McAfee and Thakur [30]. One of the compounds they examined was the nonpolar, lipid-soluble complex 8-hydroxyquinoline (oxine) (Fig. 2). Indium forms a neutral, lipid-soluble complex with oxine which will penetrate cellular membranes. Subsequently, studies showed that this technique could be used to label leukocytes and platelets with retention of biological activity [31]. After diffusing intracellularly, the ln-oxine complex dissociates and the " In is bound to nuclear and cytoplasmic proteins (Fig. 3) [32-34]. Due to the high stability of indium with the blood protein transferrin, it is necessary to label platelets or WBCs in the absence of plasma. In addition, a final wash of the labeled cells using plasma will remove any loosely bound indium by complexation with transferrin [35,36]. 

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