Small molecule ZnII) complexes containing N- and S-donor environments may serve as appropriate models for mimicking Zn protein sites, and thus, their reactions with heavy metal ions such as PtII) and W0) may provide insight into possible adduct formation and zinc displacement. To study such possible interactions between zinc finger proteins and platinum-bound DNA, the ZnN2S2 dimeric complex, N,N-bis2-mercaptoethyl)-1,4-diazacycloheptane zinc II), [Zn-1]2, has been examined for Zn-bound thiolate reactivity in the presence of PtII) nitrogen-rich compounds. The reactions yielded Zn/Pt di- and tri-nuclear thiolate-bridged adducts and metal-exchanged products, which were initially observed via ESI-mass spectrometry ESI-MS) analysis of reaction solutions, and ultimately verified by comparison to the ESI-MS analysis, 195Pt NMR spectroscopy, and X-ray crystallography of directly synthesized complexes. The isolation of Zn-micro-SR)-Pt-bridged [Znbme-dach)Cl)Ptdien))]Cl adduct from these studies is, to our knowledge, the first Zn-Pt bimetallic thiolate-bridged model demonstrating the interaction between Zn-bound thiolates and PtII). Additional derivatives involving PdII) and AuIII) have been explored to parallel the experiments executed with PtII). The [Zn-1]2 was then modified by cleavage with Na ＋[ICH2CO2]- to produce N-3-Thiabutyl)-N-3-thiapentaneoate)-1,4-diazacycloheptane) zincII), Zn-1-Ac or ZnN2SSO, and 1,4-diazacycloheptane-1,4-diylbis3-thiapentanoato) zincII), Zn-1-Ac2 or ZnN2S2O 2, monomeric complexes where S ＝ thiolate, S ＝ thioether). The [Zn-1]2 di- and Zn-1-Ac mono-thiolato complexes demonstrated reactivity towards labile-ligand tungsten carbonyl species, THF)WCO) 5 and pip)2WCO)4, to yield, respectively, the [Zn-1-Cl)WCO)4]- complex and the [Zn-1-Ac)WCO)5]x coordination polymer. With the aid of CO ligands for IR spectral monitoring, the products were isolated and characterized spectroscopically, as well as by X-ray diffraction and elemental analysis. To examine the potential for zinc complexes or zinc-templated ligands) to possibly serve as a toxic metal remediation agents, Zn-1-Ac and Zn-1-Ac2 were reacted with NiBF4)2. The formation of Zn/Ni exchanged products confirmed the capability of “free” NiII) to displace ZnII) within the N-, S-, and O-chelate environment. The Zn/Ni exchanged complexes were analyzed by ESI-MS, UV-visible spectroscopy, IR spectroscopy of the acetate regions, and X-ray crystallography. They serve as foundation molecules for more noxious metal exchange/zinc displacement products.

There are insufficient achievements in the field of cancer diagnosis and treatment for new dual agents, which would provide health care specialists the ability to simultaneously image patients cancerous tissues as well as treat the diseases. Prussian blue ferric hexacyanoferrate) is a nontoxic FDA approved compound used clinically as an antidote for thallium and radioactive cesium poisoning. In this thesis development of simple methods for the synthesis of biocompatible Prussian blue nanoparticles PBNPs) and its analogues as well as their applications for magnetic resonance imaging MRI) contrast agents and drug delivery have been studied. The extensive magnetic properties investigations show that Prussian blue nanoparticles and gadolinium doped analogue nanoparticles significantly shorten the T1 relaxation time in aqueous solution and in HeLa cells treated with PBNPs, demonstrating their potential use as MRI contrast agents. Although the relaxivity values of Prussian blue nanoparticles are approximately an order of magnitude lower than the typical commercial Gd 3＋-based T1 contrast agents but it is found to be comparable to the values obtained for the MnO nanoparticles-based T1 agents. In order to provide high contrast, gadolinium doped Prussian blue nanoparticles Gd-PBNPs) were prepared. It was also found that the Gd-PBNPs can shorten the T1 relaxation time significantly and provide potential use for clinical applications. In order for Prussian blue and its analogues nanoparticles to be concurrently utilized as drug delivery agents they must be biocompatible and capable of crossing the plasma membrane. Therefore, Prussian blue nanoparticles and related analogues were synthesized and functionalized by carboxylic acids such as citric acid as capping agents to control size distribution. To study the intracellular uptake of Prussian blue and analogue nanoparticles, their surfaces were functionalized separately with the small molecule dyes such as 5-carboxyfluorescein and Alexa FluorRTM 350 cadaverine, as well as the anticancer agent. Confocal fluorescence imaging of HeLa cells treated with the functionalized nanoparticles shows fluorescent signals in the cells suggesting intracellular uptake of the Prussian blue and Gd-PB nanoparticles. The HeLa cells internalized Prussian blue nanoparticles and gadolinium-containing Prussian blue nanoparticles could also enhance the T1 MRI contrast. The results clearly show that these nanoparticles can be used as an effective T1 contrast agent for cellular imaging. Functionalized Prussian blue nanoparticles and related analogues with both MRI contrast and drug delivery capabilities may become powerful dual agents for simultaneous cancer treatment and assessment of treatment effectiveness. Keywords: Prussian blue, coordination polymers, gadolinium, nanoparticles, imaging agents, contrast agents, magnetic resonance imaging, molecular imaging, relaxivity, drug delivery, magnetic properties.

Most previous work in low valent iron and cobalt chemistry has been through the use of carbonyl or carbonyl-derived species or through specialized precursors that are specific to a single low valent compound and often involve challenging syntheses. The methodology employed throughout this work was the direct synthesis of low valent compounds that could function as general precursors to known and many new low valent complexes of iron and cobalt. Additionally, these general precursors were synthesized under mild reaction conditions from inexpensive, commercially available transition metal halides. In Chapter 1 the synthesis, isolation, and reactivity of bisanthracene)cobaltate-I) is described. This synthesis was achieved from the anthracene radical anion mediated reduction of cobaltous bromide. In substitution reactions, this cobaltate functions as a source of Co-1 atomic anions； the anthracene ligands are very labile and are readily displaced by numerous organic molecules that can function as acceptor ligands: 1,3-butadiene, 1,3,5,7-cyclooctatetraene, cycloheptatriene, 2,6-dimethylphenylisocyanide CNXyl), 2,2-bipyridine, carbon monoxide, trifluorophosphane, and triisopropylphosphite. Reactions with ethylene and 1,5-cyclooctadiene 1,5-COD) only displaced one anthracene ligand, and the reaction with trimethylphosphane led a neutral cobalt mixed-ligand species and the regeneration of anthracene anion. In Chapter 2 a similar approach was taken using ferrous bromide, which led to the synthesis of a rare 17-electron paramagnetic complex of formally negative valent iron, bisanthracene)ferrate-I). Its reactions with 1,3-butadiene, carbon monoxide, and 2,2-bipyridine led to homoleptic ferrates. With 1,5-COD only one anthracene ligand was displaced, and with trimethylphosphite a neutral iron mixed-ligand complex and anthracene anion were synthesized. Bisanthracene)ferrate-I) was also used in situ to generate the homoleptic formally iron-II) carbonyl. If naphthalene was used instead of anthracene in the initial reduction from ferrous bromide and 1,5-COD is in the reaction mixture, a mixed-ligand naphthalene/1,5-COD, formally iron-I), species resulted, as determined by a single crystal X-ray diffraction experiment. This last species is the only example of naphthalene coordinated to a formally negative iron center. In Chapter 3 low valent iron isocyanide chemistry is examined. The reaction of ferrous bromide with four equivalents of CNXyl resulted in a mixture of the known cis- and trans-tetrakisCNXyl)ironII) bromide, which were isolated and characterized. These species were also generated in situ to generate low valent species. With sodium amalgam they led to the previously known pentakisCNXyl)iron0), which was structurally characterized as a co-crystallization of itself and its neutral dimeric form. With naphthalene radical anion the precursor ironII) species was reduced to and isolated as tetrakisCNXyl)ferrate-II), the previously unknown analog of the well-established carbonyl. This and the analogous unknown tert-butylisocyanide species were fully characterized as bistriphenylstannyl)tetrakisCNR)ironII) oxidation derivatives. When bisanthracene)ferrate-I) was reacted with excess CNXyl, it resulted in three species, one of which contained an unprecedented tridentate ligand built from six individual CNXyl ligands. In Chapter 4 the first naphthalene-containing anions of formally cobalt-I) were synthesized by the naphthalene radical anion mediated reduction of cobaltous bromide in the presence of 1,3-COD or 1,5-COD. Both forms of COD led to a mixed-ligand naphthalene)1,5-COD)cobaltate-I), the former through an isomerization. The naphthalene ligand on the cobalt center is extremely labile, and was displaced by every potential acceptor ligand employed. In reactions with 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, pyrene, trimethylphosphane, 2,2-bipyridine, ethylene, 1,5-COD, and anthracene, mixed-ligand L) x1,5-COD)cobaltate-I) were synthesized. With excellent acceptors like 1,2-bisdiphenylphosphano)ethane, CNXyl, 1,3,5,7-cyclooctatetraene, and tert-butylisocyanide, both the naphthalene and 1,5-COD ligands were displaced, leading to homoleptic cobaltates. The reduction of cobaltous bromide with naphthalene radical anion in the presence of ethylene gas resulted in the known homoleptic tetrakisethylene)cobaltate-I), only available previously from cobaltocene. An interesting re-coordination of naphthalene was observed when vacuum was applied to the reaction mixture during its synthesis, leading to the crystallographic isolation of an unprecedented triple salt containing two instances of a mixed-ligand bisethylene)naphthalene)cobaltate-I) and the first example of the elusive bisnaphthalene)cobaltate-I). This triple salt was shown to be attainable from independent reactions performed under identical conditions.

For the first time, C60-monoclonal antibody mAb) immunoconjugates have been determined to internalize into target cells using water-soluble Gd3＋-ion-filled fullerenes Gd C60OH) x). Separate conjugations of Gd C60OH)x with the antibody ZME-018 and a murine antibody mixture MuIgG) took place in a 1:5 mAb:Gd 60 ratio. Quanitative analysis of the immunoconjugates was established using inductively-coupled plasma mass spectrometry ICP-MS) and UV-Vis spectrometry Gd C60＋C60). Enzyme-linked immunosorbent assays ELISA) show little change in the specific binding of the ZME-018 once conjugated. Each immunoconjugate was exposed to two cancer cell lines, A375m a ZME-018-specific line), and T24, a bladder carcinoma line. Internalization of the immunoconjugate was measured at various timepoints, after which the cells were harvested and digested with 25% HClO3 for Gd3＋ analysis by ICP-MS. ICP-MS results show immunoconjugate internalization peaked in the first hour of exposure of the cells with a large dropoff occuring in the subsequent hour. These are the first results demonstrating the practicality of a cancer therapy based on Fullerene Immunotherapy FIT).

Hydrothermal synthesis techniques are a powerful tool to explore chemical reactions at low temperature and to discover new products with interesting structures and useful properties. This thesis reports on four reaction systems, each containing silver, using hydrothermal techniques, Te on pouch reaction vessels, and aqueous HF as a mineralizer. Understanding the complex relationship between synthesis conditions, in particular temperature and composition, led to the synthesis of three cryolite type phases of the formula Ag3MOxF6- x (M ＝ Nb, x ＝ 2； M ＝ Mo, W, x ＝ 3). A careful study of hydrolysis in these and related oxide fluoride phases enabled the synthesis of polycrystalline Ag3NbO2F4, and the development of the boiling water bath technique used to grow single crystals of the Ag3MoO 3F3 and Ag3WO3F3 phases, which form in a reversible thermodynamic process from dissolved species when the solution is heated. The theorized driving force for this reaction is the favorable dissociation of complexed molecules in solution. This new crystal growth technique overcomes challenges in traditional hydrothermal synthesis relating to pouch permeation by lowering the reaction temperature.

This thesis explores the effects of modified terphenyl ligands on the chemistry of heavier group 14 alkyne analogues. The synthesis and characterization of a series of digermynes and distannynes germanium and tin substituted analogues of alkynes) stabilized by terphenyl ligands were described. The terphenyl ligands employed are based on the Ar Ar ＝ C6H3-2,6C 6H3-2,6-iPr2)2) or Ar* Ar* ＝ C6H3-2,6C6H2-2,4,6- iPr3)2) modified by different substituents at the meta or para position of their central aryl rings to yield 4-X-Ar 4-X-Ar ＝ 4-X-C6H2-2,6C6H3-2,6- iPr2)2, X ＝ H, F, Cl, OMe, tBu, SiMe3, GeMe3) and 3,5-iPr2-Ar or Ar* and 3,5-iPr2-Ar*. The terphenyl germanium II) or tin II) halides precursors were obtained by the reaction of one equivalent of the lithium terphenyl salt with GeCl2.dioxane or SnCl2 . For germanium, their X-ray crystal structures showed them to be either Ge-Ge bonded dimers with trans-pyramidal geometries or V-shaped monomers in the case of the bulkiest terphenyls. In contrast, the corresponding tin derivatives displayed no tin-tin bonding but existed either as halide bridged dimers or monomers. Reduction of the Ge and Sn precursors with a variety of reducing agents afforded the digermynes ArGeGeAr Ar ＝ 4-Cl-Ar, 4-Me3Si-Ar or 3,5-iPr2-Ar*) or the distannynes ArSnSnAr Ar ＝ 4-F-Ar, 4-Cl-Ar, 4-MeO-Ar, 4-tBu-Ar, 4-Me3Si-Ar, 4-Me3Ge-Ar, 3,5-iPr2-Ar, 3,5- iPr2-Ar*). These compounds were characterized structurally and spectroscopically. The data showed that digermynes display planar trans-bent core geometries consistent with Ge-Ge multiple bonding with Ge-Ge distances near 2.26 A and bending angles near 128&deg；. Small molecule activation by unsaturated main group compounds is also described in this dissertation. Dihydrogen reacts directly with a range of distannynes at ca. 25&deg； under one atmosphere pressure to afford symmetric hydrogen bridged or unsymmetric stannylstannane products in high yield. The reactions of hydrogen or ammonia with germylenes and stannylenes were investigated experimentally and theoretically. Treatment of the germylene GeAr#2 Ar# ＝ C6H 3-2,6-C6H2-2,4,6-Me3)2) with H2 or NH3 afforded the tetravalent products Ar #2GeH2 or Ar#2GeH)NH 2 in high yield. The reaction of the more crowded GeAr2 Ar ＝ C6H3-2,6-C6H3-2,6- iPr2)2) with NH3 and H2 also afforded tetravalent amide Ar2GeH)NH2, whereas with H2 the tetravalent hydride ArGeH3 was obtained with ArH elimination. In contrast, the reactions with the divalent SnII) aryls did not lead to SnIV) products. Instead arene eliminated SnII) species were obtained. SnAr#2 reacted with NH3 to give the SnII) amide {Ar#Snmu-NH2)} 2 and Ar#H elimination, whereas no reaction with H 2 could be observed up to 70&deg；C. The more crowded SnAr2 reacted readily with H2, D2 or NH3 to give {ArSnmu-H)}2, {ArSnmu-D)}2 or {ArSnmu-NH 2)}2 all with arene elimination. The compounds were characterized by 1H, 13C and 119 Sn NMR spectroscopy and X-ray crystallography. DFT calculations revealed that the reactions of H2 with EAr2 E ＝ Ge or Sn； Ar ＝ Ar# or Ar) initially proceed via interaction of the sigma orbital of H 2 with the 4pGe) or 5pSn) orbital, with back donation from the Ge or Sn lone pair to the H2 sigma* orbital. The subsequent reaction proceeds by either an oxidative addition or a concerted pathway. The experimental and computational results showed that bond strength differences between germanium and tin, as well as non-bonded electron pair stabilization in tin, are more important than steric factors in determining the product obtained. In the reactions of NH3 with EAr2 E ＝ Ge or Sn； Ar ＝ Ar # or Ar), the divalent ArENH2 products were calculated to be the most stable for both Ge and Sn. Abstract shortened by UMI.)

Small molecule ZnII) complexes containing N- and S-donor environments may serve as appropriate models for mimicking Zn protein sites, and thus, their reactions with heavy metal ions such as PtII) and W0) may provide insight into possible adduct formation and zinc displacement. To study such possible interactions between zinc finger proteins and platinum-bound DNA, the ZnN2S2 dimeric complex, N,N-bis2-mercaptoethyl)-1,4-diazacycloheptane zinc II), [Zn-1]2, has been examined for Zn-bound thiolate reactivity in the presence of PtII) nitrogen-rich compounds. The reactions yielded Zn/Pt di- and tri-nuclear thiolate-bridged adducts and metal-exchanged products, which were initially observed via ESI-mass spectrometry ESI-MS) analysis of reaction solutions, and ultimately verified by comparison to the ESI-MS analysis, 195Pt NMR spectroscopy, and X-ray crystallography of directly synthesized complexes. The isolation of Zn-micro-SR)-Pt-bridged [Znbme-dach)Cl)Ptdien))]Cl adduct from these studies is, to our knowledge, the first Zn-Pt bimetallic thiolate-bridged model demonstrating the interaction between Zn-bound thiolates and PtII). Additional derivatives involving PdII) and AuIII) have been explored to parallel the experiments executed with PtII). The [Zn-1]2 was then modified by cleavage with Na ＋[ICH2CO2]- to produce N-3-Thiabutyl)-N-3-thiapentaneoate)-1,4-diazacycloheptane) zincII), Zn-1-Ac or ZnN2SSO, and 1,4-diazacycloheptane-1,4-diylbis3-thiapentanoato) zincII), Zn-1-Ac2 or ZnN2S2O 2, monomeric complexes where S ＝ thiolate, S ＝ thioether). The [Zn-1]2 di- and Zn-1-Ac mono-thiolato complexes demonstrated reactivity towards labile-ligand tungsten carbonyl species, THF)WCO) 5 and pip)2WCO)4, to yield, respectively, the [Zn-1-Cl)WCO)4]- complex and the [Zn-1-Ac)WCO)5]x coordination polymer. With the aid of CO ligands for IR spectral monitoring, the products were isolated and characterized spectroscopically, as well as by X-ray diffraction and elemental analysis. To examine the potential for zinc complexes or zinc-templated ligands) to possibly serve as a toxic metal remediation agents, Zn-1-Ac and Zn-1-Ac2 were reacted with NiBF4)2. The formation of Zn/Ni exchanged products confirmed the capability of “free” NiII) to displace ZnII) within the N-, S-, and O-chelate environment. The Zn/Ni exchanged complexes were analyzed by ESI-MS, UV-visible spectroscopy, IR spectroscopy of the acetate regions, and X-ray crystallography. They serve as foundation molecules for more noxious metal exchange/zinc displacement products.

The impact of two constitutional isomers, 2-4-BMes2-Ph)-pyridine p-B-ppy) and 5-BMes2-2-ph-pyridine p-ppy-B), as N,C-chelate ligands on the structures, stabilities, electronic and photophysical properties, and Lewis acidities of PtII) complexes has been investigated. Six PtII) complexes, Ptp-B-ppy)PhDMSO), Ptp-B-ppy)PhPy), [Ptp-B-ppy)Ph]24,4-bipy), Ptp-ppy-B)PhDMSO), Ptp-ppy-B)PhPy), and [Ptp-ppy-B)Ph]24,4-bipy), have been synthesized and fully characterized. The Lewis acidity of the complexes was examined by fluoride titration experiments using UV-Vis, phosphorescence, and NMR spectroscopic methods, establishing that the p-ppy-B complexes have stronger binding constants while the p-B-ppy complexes have a much lower affinity toward F- . A diboron compound with both 3-coordinate boron and 4-coordinate boron centers, 5-BMes2-2-Ph-Py)BMes2 B2ppy) has been synthesized, which is luminescent but have a high sensitivity toward light. UV and ambient light cause this compound to isomerize via the formation of a C-C bond between a mesityl and the phenyl group, accompanied by a drastic color change from yellow to dark olive green. The structure of the dark color species was established by 2D NMR experiments and geometry optimization by DFT calculations. The dark color species can thermally reverse back to 5-BMes2-2-Ph-Py)BMes 2 via the breaking of a C-C bond. The N, C-chelate ligand was found to play a key role in promoting this unusual and reversible photo-thermal isomerization process on a tetrahedral boron center. The impact of PtII) on the photoisomeration of four-coordinate boron center was also studied. The free ligand four-coordinate organoboron derivative B-ppy-ppy behaved in the same way as B2ppy. The photoisomeration process in the corresponding PtII) coupled complex B-ppy-ppy)PtPht-Bu-Py) is nearly completely deactivated, which may be attributed to either the low-lying 3MLCT excited state through which the excess energy in excited state was dissipated as phosphorescence or the greater pi conjugation which can stabilize the excited state.

Chapter 1. The driving forces, ethical and chemical, that have shaped TAML evolution since the early 1980s are described in a chronological fashion. The need for a clean environment sets the basis for the design. A brief introduction to FeIII-TAML oxidation catalysis is given. Studies of high valent transition metal salts and natural oxidation enzymes yielded key conceptual insights which led to TAML design for controlled oxidation catalysis. The manifestation of these ideas in the inorganic complexes produced by the Collins lab is also described, moving from the PAC complexes to todays TAMLs. Opportunities for continued TAML advancement are suggested. Chapter 2. Macrocyclic synthetic chemistry presents unique challenges. Entropic forces must be considered when selecting reaction conditions. Likewise, enthalpic forces must be considered when designing the ligand. Synthetic techniques to overcome these issues are described. Rationale and design strategies for the parent ligand of the 2nd generation of H4TAMLs, referred to as H4D*, are given. Synthetic techniques and reaction conditions are described. Progress toward other promising ligand systems is also presented. Chapter 3. Environmentally useful, small molecule mimics of the peroxidase enzymes must exhibit very high reactivity in water near neutral pH. Here we describe the design and structural and kinetic characterization of a second generation of FeIII-TAML activators 2) with unprecedented peroxidase-mimicking abilities. Iterative design has been used to remove the fluorine that led to the best performers in first-generation FeIII-TAMLs 1). The result is a superior catalyst 2e) that meets a green chemistry objective by being comprised exclusively of biochemically common elements. The rate constants for bleaching at pH 7, 9, and 11 of the model substrate, Orange II, shows that the new Fe III-TAML has the fastest reactivity at pHs closer to neutral of any TAML activator to date. Under appropriate conditions, the new catalyst can decolorize Orange II without loss of activity for at least 10 half-lives, attesting to its exceptional properties as an oxidizing enzyme mimic. Synthesis, characterization, behavior in aqueous solution, and the catalytic activity of the new D* family of the FeIII-TAML activators of peroxides designed for purification of water is also described. A comparative study of the oxidative decolorizing of the Orange II dye by H2O 2 catalyzed by the parent compound [ Fe&cubl0；OC 2&parl0；o,o- N&parr0；C6H4N CO)2CMe2}OH2)]- 2d) and its nitro 2e) and dichloro 2f) derivatives per phenylene ring) indicated superior activity of catalysts 2d and 2e at pH 7.7, though the former 2d) is by ca. three orders of magnitude less stable than the nitro-substituted catalyst 2e in aqueous solutions buffered by phosphate. For that reason 2e was chosen for systematic studies in aqueous media. Evidence is presented that 2e is an octahedral species in water. Both axial aqueous ligands are deprotonated with pK a1 and pKa1 of 8.4 and 10.0 at 25&deg；C, respectively, the former being the lowest for all FeIII-TAMLs previously reported. This is among the key reasons accounting for high catalytic activity of 2e in oxidations of organic matter by H2O 2 in neutral and slightly basic solutions. Therefore, compounds such as 2e consisting of just bioelements are valuable green oxidation catalysts for purifying environmental waters. Importantly, our studies revealed that the 2e catalyst does not display endocrine disrupting activity. X-ray structural data for 2e and 2f is reported. Chapter 4. The ligand system of H4D* was observed to have issues of hydrolytic stability when chelating iron. To observe its electron donating properties, another metal with a precedent for acid stability was needed—cobalt. Other Co-TAMLs have been previously synthesized and characterized, providing benchmark data to compare this new H4D* ligand. Physico-chemical characterization in combination with density functional theory provide a thorough analysis of this new species in its CoIII and formally CoIV states. In addition, this work also clarifies an important bifurcation in the high-valent cobalt literature. Chapter 5. Catalytic oxidation of polymers containing polybutadiene by peroxides and FeIII-TAML is described. This is an important direction for the application of Fe-TAML catalysts due to the massive volume of these commodities, and their macromolecular longevity in the environment. Reported here are reaction conditions, temporal degradation studies using polybutadiene and triblock polystyrene-butadiene-styrene) as substrates, and functional group analysis by infra-red spectroscopy. Over the course of days, the polymers are cleaved into smaller segments with acid endgroups. Chapter 6. Useful synthetic procedures are described for future Collins group chemists.

The goal of this research is to develop 64Cu radiolabeled somatostatin-receptor ligands for position emission tomography PET) imaging and radiotherapy of cancer. Copper-64 radiopharmaceuticals have been used as PET imaging agents for various diseases because of the favorable decay characteristics of 64Cu t1/2 ＝ 12.7 h； beta ＋ 17.8%)； beta- 38.4%)). Additionally, 64Cu radiopharmaceuticals have demonstrated tumor growth inhibition with a relatively low radiation dose. Many common tumors, such as those of the lung and pancreas, are not controlled by current cancer treatment and the efficacy is reduced because of severe cytotoxic effects. As a result, radiolabeled somatostatin analogs which have high affinity for somatostatin receptor subtype 2 SSTr2) have been investigated to control neuroendocrine tumors. The goals of this project are 1) to determine the role of p53 in the delivery of 64Cu to tumor cell nuclei from 64Cu-labeled somatostatin agonists and an antagonist； 2) to compare the DOTA vs. CB-TE2A chelator-conjugates of the somatostatin agonist Y3-TATE with respect to release of 64Cu in tumor cells and subsequent localization in the cell nucleus； and 3) to perform in vivo imaging of three 64Cu-labeled somatostatin analogs in HCT116 ＋/＋ and -/- tumor-bearing mice. HCT116 colorectal cancer cell clones that were either positive HCT116＋/＋) or negative HCT116-/-) for the tumor suppressor protein p53 were prepared in the laboratory of Prof. Buck Rogers Radiation Oncology) and screened for somatostatin receptor subtype 2 expression by flow cytometry FACS) analysis. Clones with the highest expression of SSTr2 from 42 p53 ＋/＋ clones and 35 clones of HCT116 p53 -/- were chosen for subsequent experiments. Receptor binding, internalization, nuclear localization, microPET, and biodistribution studies were performed with 64Cu-labeled somatostatin agonists 64Cu-CB-TE2A-Y3-TATE and 64Cu-DOTA-Y3-TATE) and an antagonist 64Cu-CB-TE2A-sst2-ANT) in SSTr2-transfected HCT116＋/＋l and HCT116-/- cells. Two different 64Cu agonist chelators with different chelate stability, CB-TE2A and DOTA, were evaluated. 64Cu-CB-TE2A-Y3-TATE showed similar binding affinity and 64 Cu nuclear localization, but faster internalization kinetics and improved in vivo stability compared to 64Cu-DOTA-Y3-TATE. As a result, 64Cu-CB-TE2A-Y3-TATE is the better choice for PET imaging and therapeutic agent. The somatostatin antagonist, 64Cu-CBTE2A- sst2-ANT, demonstrated binding to 8 to 9-fold more SSTr2 sites than the agonists, but showed lower levels of internalization and 64Cu nuclear localization. 64Cu-labeled SSTr2 antagonist showed similar tumor uptake but higher non-specific organs uptake compared to its agonist and therefore is not an improved PET imaging agent. Additionally, higher 64Cu nuclear localization was observed with the two somatostatin agonists 64Cu-DOTA-Y3-TATE and 64Cu-CB-TE2A-Y3-TATE) in the p53 positive cell line compared to the p53 negative cell line, indicating that the tumor suppressor protein p53 played a role in 64Cu trafficking into tumor cell nuclei. However, there was no difference in 64Cu nuclear localization of the antagonist 64Cu-CB-TE2A-sst2-ANT between p53 postive cell line and p53 negative cell lines, suggesting that small structural modifications of the somatostatin analogs might affect nuclear localization of 64 Cu. Receptor-targeted 64Cu-radiolabeled ligands are promising imaging and radiotherapeutic agents. Our studies investigating the intracellular trafficking of 64Cu provide vital information in the further development of these agents.