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[en] 1,5,9,13-Tetrathiacyclohexane-3,11-diol (16S4-diol), a sulfur crown ether analog, was studied as a potential chelating agent to complex no-carrier-added (NCA) grade 105Rh(III) in high yield at low ligand concentrations. trans-[RhCl2 (16S4-diol)]χ (χ = Cl, PF6) was prepared using nonradioactive RhCl3 · 3H2O and characterized by UV-Vis, nuclear magnetic resonance (NMR) and X-ray crystallography. It was shown to have a + 1 charge with the Rh(III) metal center coordinated to the four S atoms equatorially and two Cl atoms in trans axial positions. The 105Rh-16S4-diol complex prepared with NCA 105Rh(III)-chloride reagent was found to exhibit identical chromatographic properties as trans-[Rh(III)Cl2(16S4-diol)]+ (including silica and C-18 thin-layer chromatography [TLC] and electrophoresis). The preparation of 105Rh-16S4-diol complex formation optimized for conditions of pH, temperature, time, % ethanol and quantity of 16S4-diol resulted in yields >90%. Very low quantities of 16S4-diol (3 nmol) complex NCA 105Rh(III) under relatively mild reaction conditions (heating at 64 deg. C for 90 min) in the presence of ethanol (10%), yielded the high specific activity 105Rh-16S4-diol complex as a single cationic species. The 105Rh-16S4-diol complex was shown to be stable for ≥4 days in physiological buffers at room temperature and in human serum at 37 deg. C
[en] Introduction: Tetradentate acyclic and macrocyclic diphosphine ligands (P2N2 and P2S2) have been synthesized and characterized as potential chelates for Rh(III). Methods: The coordination complexes [RhCl2(L1)]Cl, trans-[RhCl2(L2)]PF6, [Ni(L2)](PF6)2, [Ni(L3)](PF6)2, [RhCl2(L4)]PF6 and [RhCl2(L5)]PF6 have been synthesized and characterized. In addition, radiochemistry studies of the 105Rh complexes with the ligands N,N'-bis[2-(diphenylphosphino)phenyl]-1,3-diaminopropane (L1), 4,8-diphenyl-1,11-diaza-4,8-diphosphaundecane (L2), 5,9-diphenyl-5,9-diphospha-2,12-dithiatridecane (L3) and 1,4,8,11-tetraphenyl-4,8-diphospha-1,11-dithiaundecane (L4) are reported, including normal mouse biodistributions of 105Rh-L2. Results: trans-[RhCl2(L2)]PF6 crystallized in the monoclinic space group P21/c with a=9.9353(5) A, b=9.0929(5) A, c=28.689(1) A, β=93.1400(10) deg, Z=4, R=0.037 and Rw=0.053. [Ni(L2)](PF6)2 crystallized in the monoclinic space group P21/c with a=11.9665(6) A, b=14.8903(7) A, c=31.148(1) A, β=91.587(1) deg, Z=8, R=0.056 and Rw=0.083. μ-O2SO2-[Ni(L5)]2(PF6)2, an unusual sulfate-bridged Ni(II) dimer, crystallized in the triclinic space group P1 bar with a=15.179(2) A, b=15.514(2) A, c=16.128(2) A, α=105.280(7) deg, β=113.074(6) deg, γ=101.657(8) deg, Z=2, R=0.050 and Rw=0.072. Conclusions: Phosphine-containing ligands allowed for lower temperatures and lower ethanol concentrations in the formulations for 105Rh(L) complexation, but at the expense of higher ligand concentrations.
[en] 105Rh[1,5,9,13-tetrathiacyclohexadecane-3,11-diol] is a promising drug precursor for targeted radiotherapy. Nevertheless, the axial position of chloride ions in the complex structure and their weak binding to rhodium centre, due to HSAB concept, make such a complex subject to modifying action of certain sulphuric ligands, like human plasma thiol antioxidants: glutathione and cysteine. Experiments were performed with both radioactive 105Rh and inactive rhodium. The complexation of rhodium with 1,5,9,13-tetrathiacyclohexadecane-3,11-diol (16S4diol) resulted in three distinct peaks seen on UV, radiometric and MS chromatograms. The substitution of chlorides was noted in over 80% of 105[Rh(16S4diol)Cl2]+ units after incubation with glutathione, and less than 10% of complex units after incubation with cysteine (24 h, 37 deg C). Reaction of 105[Rh(16S4diol)Cl2]+ with 1,8-octandithiol and 1,9-nonandithiol resulted in disappearance of the complex peak and occurrence of two new peaks. Product of RhCl3 and 16S4diol reaction is a mixture of three distinct forms having different number of chlorine atoms. Our in vitro experiments suggest that the substitution of axial chlorides with glutathione and cysteine might also occur in vivo in human plasma. Glutathione shows higher reactivity than cysteine in replacement reaction. Axial positions in precursor might be effectively blocked by 1,8-octandithiol and 1,9-nonandithiol. (author)
[en] Following the reports of two pairs of chiral doublet bands observed in 105Rh, the adiabatic and configuration-fixed constrained triaxial relativistic mean-field calculations are performed to investigate their triaxial deformations with the corresponding configuration and the possible multiple chiral doublet (MχD) phenomenon. The existence of the MχD phenomenon in 105Rh is highly expected.
[en] Production cross-sections of the therapeutic 105Rh radionuclide from proton-induced reactions on natural palladium target were measured using stacked-foil activation technique combined with high resolution gamma -ray spectrometry at the MC50 cyclotron of the Korea Institute of Radiological and Medical Sciences. Note that cyclotron production of the 105Rh radionuclide from natural palladium target was measured here for the first time. Results are compared with the theoretical values obtained using the model codes TALYS and ALICE-IPPE. Thick target integral yields for the investigated 105Rh radionuclide were deduced from the threshold energy to 40 MeV. Measured data of the 105Rh radionuclide are important because of its potential applications in nuclear medicine and/or therapeutic purposes. Optimal production circumstances for the therapeutic 105Rh radionuclide using a cyclotron are discussed elaborately. (author)
[en] Following a fast chemical separation of Ru isotopes from a fission-product mixture, 105mRh was periodically extracted from its precursor (4.44-h 105Ru) for measurements of its half-life. The new value for the T1/2 of 105mRh of (43.0±0.3) s resolves the long-standing conflict in the literature between the two earlier measured values of 45 and 30 s