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Delivery of NO to specific targets is important in fundamental studies and therapeutic applications. Various methods have been reported for delivery of NO in vivo and in vitro; however, there are few examples of systems that reversibly bind NO. Reported herein is the development of a new polymer (P-1[Co(II)]) that reversibly binds NO. P-1[Co(II)] has a significantly higher affinity for NO compared to O(2), CO(2), and CO. The polymer is synthesized by template copolymerization methods and consists of a porous methacrylate network, containing immobilized four-coordinate Co(II) sites. Binding of NO causes an immediate color change, indicating coordination of NO to the site-isolated Co(II) centers. The formation of P-1[Co(NO)] has been confirmed by EPR, electronic absorbance, and X-ray absorption spectroscopies. Electronic and X-ray absorbance results for P-1[Co(II)] and P-1[Co(NO)] show that the coordination geometry of the immobilized cobalt complexes are similar to those of their monomeric analogues and that NO binds directly to the cobalt centers. EPR spectra show that the binding of NO to P-1[Co(II)] is reversible in the solid state; the axial EPR signal associated with the four-coordinate Co(II) sites in P-1[Co(II)] is quenched upon NO binding. At room temperature and atmospheric pressure, 40% conversion of P-1[Co(NO)] to P-1[Co(II)] is achieved in 14 days; under vacuum at 120 degrees C this conversion is complete in approximately 1 h. The binding of NO to P-1[Co(II)] is also observed when the polymer is suspended in liquids, including water.

A thermodynamic model of the distribution of Pu(IV) between aqueous solutions of nitric acid and lithium nitrate and 30 % (by volume) TBP in n-dodecane was developed. The mean activity coefficients of the hydrogen ion, nitrate ion, and water were calculated using Bromley's method of activity coefficients. The computation of the distribution ratios is based on a critical evaluation of the speciation of Pu(IV) under the solution conditions used. Five Pu(IV) species, Pu 4+ , Pu(OH) 3+ , Pu(OH) 2 2+ , Pu(NO 3 ) 3+ , and Pu(NO 3 ) 2 2+ , were considered to be present in (0.1 to 4) mol • L -1 aqueous solutions of HNO 3 . Because of the various extraction capabilities of the different oxidation states of Pu, disproportionation of Pu(IV) is the main factor controlling the distribution of Pu at low acidity. Two different Pu(IV) solvate adducts Pu(NO 3 ) 4 • TBP 2 and Pu(NO 3 ) 4 • TBP 2 • HNO 3 were considered as extracted species over a wide range of experimental conditions, and their extractions constants were determined. The correlation between experimental and calculated data produced a reasonable fit. To determine the extraction constant of hydrolyzed Pu(IV) species for low acid concentrations, additional experimental data on the kinetics of disproportionation of tetravalent plutonium in two phase systems would be necessary.

Copolymerization of molecular assemblies into organic hosts is an effective way of fabricating new materials having desirable chemical or physical properties. The assembly of the molecular species prior to polymerization is advantageous because of the greater control of the structure and amount of species incorporated into the polymer and the possibility of regulating their microenvironments. Recent examples of this method in the synthesis of new polymers include the monodispersal of metallic nanoclusters into organic polymer hosts' and molecular imprinting of selective binding sites into highly cross-linked network polymers.2 We describe herein an application of this copolymerization approach for designing metal ion sites in network polymers.3•4Our objective is to use the copolymerization process to synthesize sites in the polymer that can bind metal ions or stabilize metal-small molecule adducts. The macroporous character of these polymers should allow the incorporated metal ion to bind additional ligands not present during polymerization.

Template copolymerization methods have been used to make materials for a wide variety of applications where site-specific analyte binding is desired. The structure of the binding site is often crucial to the efficient function of the material. We have immobilized cobaltcontaining template complexes in porous organic hosts, allowing the use of spectroscopy to conveniently probe the site structure. Reported herein are results from X-ray diffraction and X-ray absorption spectroscopy (XAS) studies for a series of monomerswhere 1 is the ligand bis[2-hydroxy-4-(4-vinylbenzylmethoxy)benzaldehyde]ethylenediimine and 2 is bis[2-hydroxy-4-(4-vinylbenzylmethoxy)benzyliminopropyl]methyl amine} and related copolymers. Copolymerization of the 6-coordinate complex [Co III 1(dmap) 2 ][PF 6 ] with an organic cross-linker forms immobilized 6-coordinate cobalt sites in P-1[Co III (dmap) 2 ]. Similar findings were obtained for the formation of immobilized cobalt sites in P-2[Co III (1-MeIm)]. Demetalation of P-1[Co III (dmap) 2 ] and P-2[Co III -(1-MeIm)] affords immobilized sites that contain tetra-or pentadentate ligands, respectively. Rebinding of Co II ions affords P-1[Co II ] with sites containing cobalt complexes having square planar coordination geometry, whereas P-2[Co II ] has immobilized square pyramidal cobalt complexes. XAS studies support these coordination geometry assignments and show that the rigidity of the porous host maintains site architecture even after chemical modification.

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99 Mo, the parent of the widely used medical isotope 99m Tc, is currently produced by irradiation of enriched uranium in nuclear reactors. The supply of this isotope is encumbered by the aging of these reactors and concerns about international transportation and nuclear proliferation. Methods: We report results for the production of 99 Mo from the accelerator-driven subcritical fission of an aqueous solution containing low enriched uranium. The predominately fast neutrons generated by impinging high-energy electrons onto a tantalum convertor are moderated to thermal energies to increase fission processes. The separation, recovery, and purification of 99 Mo were demonstrated using a recycled uranyl sulfate solution. Conclusion: The 99 Mo yield and purity were found to be unaffected by reuse of the previously irradiated and processed uranyl sulfate solution. Results from a 51.8-GBq 99 Mo production run are presented. Thedaught er of 99 Mo (half-life, 66 h), 99m Tc (half-life, 6 h), is used in more than 45 million diagnostic nuclear medicine procedures annually worldwide, with approximately 16.7 million procedures performed in the United States alone (1). Despite being the largest single user of 99m Tc, the United States currently imports 100% of its supply (2). Current supply chains of 99 Mo rely on aging nuclear reactors, such as the High Flux Reactor in The Netherlands and the National Research Universal reactor in Canada (1). The major U.S. supplier, located in Canada, will cease normal production in late 2016 but will maintain the ability to produce 99 Mo for another 2 y, if a severe shortage occurs (3). The High Flux and National Research Universal reactors have exceeded their initial design lifetimes of 40 y, having been in operation for 55 and 59 y, respectively. In 2009-2010, both reactors were shut down for extended periods of time, causing a severe 99 Mo shortage (4,5). The 99 Mo shortage forced clinicians to ration imaging procedures, which delayed critical diagnostic tests or resulted in older, less effective techniques that in many cases increased the radiation dose to the patient (6). The U.S. 99 Mo market is also fragile because it relies solely on international air transportation, which has been halted in the past due to inclement weather, natural phenomena, flight delays, and terrorist threats (6).The predominant global 99 Mo production route is irradiation of highly enriched uranium (HEU, $20% 235 U) solid targets in nuclear reactors fueled by uranium (2). Other potential 99 Mo production paths include (n,g) 98 Mo and (g,n) 100 Mo; however, both routes require enriched molybdenum material and produce low-specificactivity 99 Mo, which cannot be loaded directly on a commercial 99m Tc generator. The U.S. National Nuclear Security Administration implements the long-standing U.S. policy to minimize and eliminate HEU in civilian applications by working to convert research reactors and medical isotope production facilities to low enriched uranium (LEU, ,20% 235 U) worldwide (7). In 2009, the Global...