Syntheses and structures of molybdenum and tungsten complexes capable of epoxidaton and copper coordination polymers and dendrimers

We are interested in the syntheses of new complexes and in their characterization by single crystal X-ray diffraction techniques. Once we understand the structures, studies aimed at understanding uses of these complexes in the field of catalytic epoxidation using complexes soluble in water and syntheses of thin films (not assessed) were conducted. The syntheses, characterization and catalytic properties of a series of mononuclear, dinuclear and tetranuclear molybdenum and tungsten oxo complexes are described. The syntheses and structural characterization of two copper coordination polymers with 3,5-dihydroxylbenzoate ligand, and five paddlewheel shaped copper dendrimers coordinated with Fréchet-type dendrons are also detailed. The background of this dissertation is outlined in Chapter 1. Chapter 2 describes the syntheses, and characterization of two new mononuclear molybdenum(VI) and tungsten(VI) oxo complexes, MoO2Cl2(OPPh2CH2OH)2, and WO2Cl2(OPPh2CH2OH)2, bearing hydrophilic phosphine oxide ligand. The catalytic properties of these complexes for the epoxidation of cis-cyclooctene were also studied. Two new dinuclear molybdenum(VI) and tungsten(VI) oxo complexes Mo2O4Cl2[(HOCH2)PhPOO]2, and (CH3O)2(O)W(μ-O)(μ-O2PPh2)2W(O)(CH3O)2, bearing organophosphinate ligand are described in Chapter 3 and 4. Chapter 4 and 5 describes the syntheses and characterization of tetranuclear molybdenum(V) oxo complexes bearing various organophosphinate ligands. The catalytic abilities of these complexes for the epoxidation of cis-cyclooctene in the presence of hydrogen peroxide as oxidant were explored as well. Various spectroscopic methods, such as IR, UV-vis, and NMR are used to characterize the nature of these complexes. Crystal structures of compounds MoO2Cl2(OPPh2CH2OH)2, WO2Cl2(OPPh2CH2OH)2, Mo2O4Cl2[(HOCH2)PhPOO]2, (CH3O)2(O)W(μ-O)(μ-O2PPh2)2W(O)(CH3O)2, and Mo4(µ3-O)4(µ-O2PR2)4O4 (R=Ph, Me, ClCH2, o-C6H4(CH2)2) are also presented. The syntheses, and structural characterization of three copper(II) coordination polymers bearing 3,5-dihydroxybenzoate ligand are described in Chapter 6. Two copper(II) coordination polymers, [Cu2(3,5-dhb)2(pyridine)4]n, and [Cu2(3,5-dhb)4]n were afforded based on different amount of pyridine used in the reaction. The structures of these complexes are further built into 2D or 3D networks via inter or intra hydrogen bonds. The syntheses and structural characterization of the zinc(II) monomer, Zn(3,5-dhb)2(pyridine)2 is also described in this Chapter. Chapter 7 describes the syntheses, and characterization of five dendronized dicopper complexes bearing different generations of Fréchet-type dendrons. The structures of 3,5- bis(benzoyloxl)benzoic acid, 3,5-(PhCOO)2PhCOOH (G1), Cu2(3,5-dhb)4(THF)2, Cu2(G1)4(pyridine)2, and Cu2(G1)4(CH3OH)2 were characterized unambiguously by single X-ray diffraction. In addition, all compounds were characterized by FT-IR, UV-vis spectroscopy and elemental analyses.

The Planned and the Emergent: An Alternative Model of Learning and Literacy

Within academic institutions, writing centers are uniquely situated, socially rich sites for exploring learning and literacy. I examine the work of the Michigan Tech Writing Center's UN 1002 World Cultures study teams primarily because student participants and Writing Center coaches are actively engaged in structuring their own learning and meaning-making processes. My research reveals that learning is closely linked to identity formation and leading the teams is an important component of the coaches' educational experiences. I argue that supporting this type of learning requires an expanded understanding of literacy and significant changes to how learning environments are conceptualized and developed. This ethnographic study draws on data collected from recordings and observations of one semester of team sessions, my own experiences as a team coach and UN 1002 teaching assistant, and interviews with Center coaches prior to their graduation. I argue that traditional forms of assessment and analysis emerging from individualized instruction models of learning cannot fully account for the dense configurations of social interactions identified in the Center's program. Instead, I view the Center as an open system and employ social theories of learning and literacy to uncover how the negotiation of meaning in one context influences and is influenced by structures and interactions within as well as beyond its boundaries. I focus on the program design, its enaction in practice, and how engagement in this type of writing center work influences coaches' learning trajectories. I conclude that, viewed as participation in a community of practice, the learning theory informing the program design supports identity formation —a key aspect of learning as argued by Etienne Wenger (1998). The findings of this study challenge misconceptions of peer learning both in writing centers and higher education that relegate peer tutoring to the role of support for individualized models of learning. Instead, this dissertation calls for consideration of new designs that incorporate peer learning as an integral component. Designing learning contexts that cultivate and support the formation of new identities is complex, involves a flexible and opportunistic design structure, and requires the availability of multiple forms of participation and connections across contexts.