Column chromatography of carrier-free Tc/III,IV/-TTA complexes

The chemical species of carrier-free technetium, which were extractable into a TTA-benzene solution on reduction of⁹⁶TcO ₄ ^– either with NaBH₄ or concentrated HCl, were studied by means of silica gel chromatography. Elution peaks ascribed to the formation of Tc/tta/₄ and Tc/tta/₃ type complexes were observed. The latter complex was also synthesized by recoil effect of Ru/, p/Tc reactions in -irradiated Ru/tta/₃.     

Mechanisms of chemical reaction initiated by recoil implantation

Mechanisms of chemical reactions initiated by recoil implantation were studied in the systems⁵¹Cr+M/acac/₃⁵¹Cr/acac/₃ where M is a trivalent metal. The yield of⁵¹Cr/acac/₃ increased linearly with an increase of inverse of the force constant of metal-oxygen bonding K(M–O). This indicates that there is competition between the implanted⁵¹Cr atom and M. However, exception for this trend was the case of Co/acac/₃ catcher, for which the yield of⁵¹Cr/acac/₃ was much higher than that expected for a competition reaction. Complex features of the replacement reaction caused by implantation are discussed in this system.     

A new detection method of99Tc by nuclear excitation

A new nuclear excitation process,⁹⁹Tc (, )^99mTc reaction, was applied for the first time to radioactivation analysis of technetium. Bremsstrahlung irradiation of⁹⁹Tc samples gave the reaction product^99mTc which emits -ray measurable with ease by a semiconductor detector. The production rate of^99mTc per g⁹⁹Tc was linearly correlated with the flux of bremsstrahlung. The detection limit of⁹⁹Tc was estimated to be nanogram order (0.63 Bq⁹⁹Tc) under the optimum irradiation condition. Possible interference by¹⁰⁰Ru(, p)^99mTc reaction was also studied, which could be discriminated from the (, ) reaction by simultaneously occurring⁹⁸Ru (, p)⁹⁷Ru reaction.     

Measurement of103mRh produced by the103Rh/γ, γ′ /103mRh reaction with liquid scintillation counting

A liquid scintillation counting technique was applied to measure the isotope^103mRh /half life = 56.12 min/ which is difficult to detect because its -ray is of low energy and low emission probability. Tris-/2,4-pentanedionato/ rhodium /III/ /Rh/ acac/₃/ was irradiated with bremsstrahlung of accelerated 3.2 MeV electrons by LINAC. The method has given a reliable calibration curve for the determination of^103mRh radioactivity below Rh/acac/₃ concentrations of 2 mM. The integrated cross section of¹⁰³Rh/,/^103mRh determined by this method was found to be 6.8±3.4 b MeV at 3.2 MeV.     

Decay of 1.643-hr 95Ru to 95Tc

The decay of ⁹⁵Ru has been investigated by means of -ray spectroscopy. The ⁹⁵Ru nuclei were produced by the reaction ⁹²Mo(,n)⁹⁵Ru at the beam energy of 17 MeV. High-purity Ge detectors have been used singly and in coincidence to study -rays in the decay of ⁹⁵Ru to ⁹⁵Tc. 132 -rays are reported, among them, energies and intensities for 127 transitions have been determined. A decay scheme of ⁹⁵Ru with 31 levels is proposed which accommodates 127 of these transitions. Spins and parities for three new levels are proposed from calculated logft values, measured -ray branching ratios, and in-beam experiment results of the daughter nucleus ⁹⁵Tc.     

Recoil implantation reaction in geometrical isomers of tris/benzoylacetonato/chromium/III/

Hot atom chemical reaction by⁵⁰Cr/n, /⁵¹Cr and⁵²Cr/, n/⁵¹Cr reactions, and recoil implantation reaction by⁵¹V/p, n/⁵¹Cr reaction were investigated using geometrical isomers /mer and fac/ of tris/benzoylacetonato/ chromium/III/ /Cr/ba/₃/. The production of counter isomer was observed for both mer- and fac-targets, although the yield of labelled parent isomer was larger. The observed mer/fac yield ratio suggests that the main formation mechanism of⁵¹Cr/ba/₃ is the reaction of ba^– and Cr/ba/ ₂ ⁺ which has the same geometrical configuration of target complex, and the substitution reaction of central metal atom by recoil⁵¹Cr. Furthermore, implantation gave rise to a much higher yield of labelled Cr/ba/₃ compared to the case of in situ nuclear recoils.     

Some observations on the synthesis and HPLC of tris-(acetylacetonato)technetium(III) and (IV) complexes

[⁹⁹Tc(III) (acac)₃] was synthesized by published procedure, but recovered by extraction into CH₂Cl₂. The product was purified by preparative HPLC over a reversed phase column, RP18, using a mobile phase of 11 CH₃OHH₂O. The cationic complex [⁹⁹Tc(IV) (acac)₃]⁺ prepared by the oxidation of the purified neutral Tc(III) complex was unstable in methanol/methanol-water medium, being reduced back to the Tc(III) complex.     

Phenylisocyanation and bromination studies on lanthanide β-diketonates

Summary Phenylisocyanation and bromination of some twenty lanthanide -diketonates: Ln(acac)₃, Ln(bzac)₃ and Ln(dbzm)₃ where Ln=Pr^III, Nd^III, Sm^III, Gd^III, Dy^III and Y^III and Ce(acac)₄, Ce(bzac)₄ and Ce(dbzm)₄ have been investigated. While phenylisocyanation gives the expected 3-substituted phenylamido product, bromination, for the first time, has been observed to yield a substituted product with flipping of one (or two) six-membered diketone ring to give a five-membered ring in which the entering bromine electrophile is bonded to the metal and a carbon atom. The other diketone rings, although -substituted, remain intact with respect to metal coordination. The substituted complexes have been characterised by i.r., u.v. and n.m.r. spectroscopy.     

Characterisation of lead rhodizonate as barium and radium adsorber from fresh water

A series of metal -diketonates were irradiated with bremsstrahlung of maximum energy of 50 MeV and the recoil behavior of⁷Be, formed from¹²C of ligands through¹²C(, n)⁷Be reaction, was investigated.⁷Be nuclides thus formed were detected partially as central metal atoms of the complexes. Complex yields of⁷Be were compared and an anomalously high yield was observed in tris-acetylacetonatocobalt(III) [Co(acac)₃].     

‘Effective hot reaction zone’, caging energy and normalized appearance energy in ruthenium complexes

In contrast to the single molecule cage of Ru/acac/₃ a cage involving wall molecules of RuCp₂ is formed in recoil reaction of radioruthenium atoms. Enhancement of the parent yield in RuCp₂ is ascribed to the larger size of the cage /effective hot reaction zone/ compared to the case of Ru/acac/₃. A normalized appearance energy technique has been applied to estimate energy /AE _adj ^x / necessary for caging the recoil atom in RuCp₂. AE _adj ^x is about twice as large as caging energy CE. The relation of AE _adj ^x to CE in RuCp₂ is nearly the same as that of AE^x to bonding energy BE in Ru/acac/₃.     

A new approach to the study of normalized appearance energy of hot atom reaction product in optical isomers of tris/acetylacetonato/ruthenium/III/

Appearance energy is originally the threshold energy at which récoil products begin to be observed. This was determined by /, '/ reactions. Afterwards, an alternative technique has been developed to determine it by summing up recoil energy spectrum. The latter technique assumed a step function rising at energy E_O in the yield-energy relation. E_O should be defined as normalized appearance energy /NAE/, because it is not threshold energy in its original sense. The NAE for isomerization from to /or reverse/ in Ru/acac/₃ was estimated to be 29 eV, and that for free atom /or ion/ formation was calculated to be 34 eV. The 5 eV difference seems to indicate an energy interval in which isomerization effectively occurs in the recoil reaction.     

Stabilities in Polar Nonaqueous Solvents and Transfer Activity Coefficients from Water to Nonaqueous Solvents of 19-Crown-6-Alkali Metal Ion Complexes

Formation constants of 1 : 1 19-crown-6(19C6) complexes with alkali metal ions weredetermined conductometrically at 25 °Cin acetonitrile(AN), propylene carbonate (PC), methanol, DMF, andDMSO. 19C6 always forms the most stable complex withK⁺. The selectivity order of 19C6 forheavy alkali metal ions isK⁺ > Rb⁺ > Cs⁺.The selectivity for Na⁺ varies withthe solvent; that for Li⁺ is the second lowest(AN, DMSO) or the lowest (PC). Transfer activity coefficients(^SH _{2 O}) of19C6 from water to the nonaqueous solvents (S) weremeasured at 25 °C. The contributions of a methylenegroup and an ether oxygen atom to thelog ^SH _{2 O}value of a crown ether wereobtained. The ^SH _{2 O}values of the 19C6–alkali metal ion complexes(^SH _{2 O} (ML⁺)) werecalculated, M⁺ and L denoting an alkali metal ionand a crown ether, respectively. For AN, PC, andCH₃OH, although the M⁺ ion is more stronglysolvated by water than by AN, PC, or CH₃OH, thelog ^SH _{2 O} (ML⁺) islarger than the correspondinglog ^SH _{2 O} (L)expect for the case of M⁺ = Li⁺.The higher lipophilicity of the19C6 complex ion is attributed to an enforcement ofthe hydrogen-bonded structure of water for the complexion caused by the greatly decreased hydrogen bondingbetween ether oxygen atoms and water uponcomplexation. For DMF and DMSO, thelog ^SH _{2 O} (ML⁺) is also greater thanthe correspondinglog ^SH _{2 O} (L).It was concluded from thisfinding that the unexpectedly lowest stability of the19C6 complex ion in water is due to the hydrogenbonding between 19C6 and water. The stabilities and thelog ^SH _{2 O}of 19C6–alkali metal ion complexes were compared with those of 18C6complexes.     

The recoil reaction of technetium in mer- and fac-tris/benzoylacetonato/ruthenium/III/

The recoil reactions of technetium produced by¹⁰⁰Ru/γ, p/^99mTc reaction were studied in γ-irradiated mer- and fac-Ru/ba/₃ targets. Yields of mer- and fac-Tc/ba/₃ were determined by column chromatographic separation developed in our previous work. In the initial recoil reaction yields mer-form of Tc/ba/₃ was much more abundant than fac-form in the mer-Ru/ba/₃, but the reverse held good in the fac-Ru/ba/₃ showing selectivity in recoil replacement reactions in geometrical isomers. In the annealing reactions, however, such selectivity disappeared and the fac/mer ratio for the annealed portions could be explained by the following mixed mechanisms of ligand incorporation. $$\begin{gathered} Tc/ba/_2^ + + ba^ - \to Tc/ba/_3 \hfill \\ Tc/ba/^{2 + } orTc^{3 + } + xba \to Tc/ba/_3 \hfill \\ /x = 2or3/. \hfill \\ \end{gathered} $$      

Simultaneous determination of some long-lived semivolatile radionuclides in environmental samples

A radiochemical method is presented to determine simultaneously the long-lived semivolatile radionuclides⁷⁹Se,⁹⁹Tc,¹⁰⁶Ru,¹²⁵Sb,^125mTe,^127mTe,¹³⁴Cs and¹³⁷Cs in environmental samples. The pure -emitters⁷⁹Se and⁹⁹Tc are counted in a low-level gas flow counter, the -emitters in a -spectrometer with a high purity well-type Ge detector. The procedure was tested using environmental samples with known concentrations of⁹⁹Tc,¹⁰⁶Ru,¹²⁵Sb,¹³⁴Cs and¹³⁷Cs.     

Specific radiation and recoil energy effects in recoil implantation reaction of51Cr in metal acetylacetonates

In recoil implantation reaction of⁵¹Cr in Cr/acac/₃ a polymer component which was sensitive to radiation dose was found. However, a retention type component⁵¹Cr/acac/₃ was not so sensitive to radiation dose. A remarkable dependence of the yield of⁵¹Cr/acac/₃ on recoil energy was found in the range 10²–10⁶ eV in recoil implantation using a thin film technique. This suggests a special role of implantation reaction in solids.     

Properties of a multiple bond conjugated with the pyridine ring

The products of the addition of diazomethane to the double bond of -, -, and -vinyl-pyridines, 2-propenyl-, 2-styryl-, and 2-(p-nitrostyryl)pyridines, and -(2-pyridyl)acrylic acid were obtained. When a hydrogen atom or alkyl or phenyl group is present in the -position of the vinyl group, 3-pyridyl-²-pyrazolines are formed (they are isolated as the acetyl derivatives). Electron-acceptor substituents (COOCH₃ and C₆H₄NO₂) in this position disrupt the polarization, and this leads to the formation of a mixture of two isomeric pyrazolines. The primary formation of ¹-pyrazolines was proved by means of IR and UV spectroscopy.See [1] for communication IX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 64–69, January, 1973.     

Fluorescent Molecular Sensing System Based on Tri-Pyrenes-Labeled γ-Cyclodextrin at the Hetero Rim

Fluorescent active host labeled at the upper and lower rims of -cyclodextrin, namely, mono-3^A-deoxy-3^A-pyrenebutylamido-6^X,Y-O-bis-pyrenebutylate-mono-altro--cyclodextrin (-3) has been synthesized as a chemosensor for steroidal guests using fluorescence spectra change upon a guest addition. The -3 shows monomer and excimer fluorescence, which results in an increase of the intensity of monomer and decrease of excimer fluorescence with a host–guest binding in the cyclodextrin cavity. The extent of monomer and excimer fluorescence variations of -3 was used as an indication for the sensing ability for the guests examined. The guest-induced fluorescence changes were measured for 10^–7 M solutions of -3. The sensing parameters (I_ex/I⁰_ex and I_mon/I⁰_mono) were used to describe the sensing ability of -3. The values of I_ex/I⁰_ex describe that -3 shows less selectivity for guests than that of mono-3^A-deoxy-3^A-pyrenebutylamido-6^X-O-mono-pyrenebutylate-mono-altro--cyclodextrin (-2), and the values of I_mon/I⁰_mono show that -3 shows higher sensitivity and selectivity than that of -2.     

95Tc and96Tc production by (γ, xn) reactions

The⁹⁹Tc (, 3n)⁹⁶Tc and⁹⁹Tc (, 4n)⁹⁵Tc reactions were studied by irradiation of target⁹⁹Tc with bremsstrahlung from the linear electron accelerator of Tohoku University, up to 50 MeV -energy. The resulting⁹⁶Tc (4.3 d) and⁹⁵Tc (20 h) activities were determined by -spectrometry. The -flux was monitored by the⁹⁹Tc (, )^99mTc reaction. Metallic copper and gold foils were used as additional flux monitors in front of and behind the samples. Their measured radioactivity was utilized for normalizing bremsstrahlung flux calculations, in order to determine reaction cross sections. Cross sections were also determined theoretically, performing calculations in the framework of a neutron cascade evaporation model. Above the (, 3n) and (, 4n) threshold energies the neutron emission channel was supposed to be the only open channel for deexcitation following photoabsorption. The preeguilibrium contribution was considered negligible. The experimental results obtained for the integrated cross section at 30 and 50 MeV fit reasonably well the calculated curves.     

Distribution of gamma radionuclidic impurities in routine99mTc generator eluates

Fission-produced -emitting radionuclidic impurities in eluates obtained by elution of routine (n,f)⁹⁹Mo/^99mTc generators have been determined. Four radionuclidic impurities were identified and quantitatively measured by the method of -spectrometry. The distribution of¹⁰³Ru,¹⁰⁶Ru,¹²⁵Sb and¹³¹I in the eluates was followed. The fraction of the activity which has been desorbed from alumina in the generator column during the lifetime of the generator was determined for earch radionuclide found. The contents of radionuclidic impurities in the eluates were compared with the criteria of radionuclidic purity prescribed by the Pharmacopoeia.