1. Dioxygen reactivity of multinuclear fluorinated copper(I) alkoxides facilitated by secondary ligand interactions 2. synthesis and characterization of monomeric O-donor complexes of divalent copper and zinc

Thesis (Ph.D.)--Boston University PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at [email protected]. Thank you.Copper(I) complexes with fluorinated alkoxide ligands with the form K[Cu(OCRMe^F2)2], in which R = Me^F (4), Ph (5), or Me (6), were synthesized and characterized. The dioxygen (O2) reactivity of the series of complexes was investigated at -78°C and two stoichiometries of {CunO2} species were observed. Manometric O2 uptake studies showed dinuclear {Cu2O2} and triuclear {Cu3O2} species and their chromophores were measured with UV-vis spectroscopy. Warming these species to room temperature resulted in irreversible spectroscopic changes, and ligand hydroxylation was observed for complexes 5 and 6. ESI-MS study of reactions with 18O2 confirmed O2 as the source of the ligand hydroxyl O atom. A tetrameric Cu(II) carbonate complex, {{K2(DME)1.5}[Cu(OCMeMe^F2)2C03]}4 (14), was obtained from CO2 addition to the {Cu2O3} moiety derived from 6. Irreversible reduction of O2 required secondary potassium-ligand (K···F and K-O) interactions which bridge multiple [Cu(OCRMe^F2)2]- anions in solid-state structures of 4, 5, and 6, and were quantified by K+ cation bond valence analysis. Solution conductivity studies confirmed that neutral aggregates of K[Cu(OCRMe^F2)2] complexes are retained in solution. Ionic copper(I) complexes of the form {K(18C6)}[Cu(OCRMe^F2)2] in which R = Me^F (7), Ph (8), or Me (9) and (Ph4P)[Cu(OCRMe^F2)2], with R = Me^F (10) were prepared, none of which react with O2 at -78°C. The Cu(II) alkoxide compounds {K(18C6)}[Cu(OCRMe^F2)3], in which R= Me^F (15) and Me (16) were prepared and spectroscopically and magnetically characterized. Compound 16 was demonstrated to be trigonal-planar by X-ray crystallography and all other data for 15 are consistent with trigonal-planar coordination. Two four-coordinate Cu(II) compounds with dodecafluoropinacolate (ddfp) ligands were also synthesized and characterized spectroscopically. The structurally characterized square-planar ddfp compounds have the form {K(solvent)2}2[Cu(ddfp)2], in which solvent= H2O (17) or DME (18). Diamagnetic Zn(II) derivatives with aryloxide ligands of the form {K(18C6)}2[Zn(OAr)4], m which Ar = A^F (19) or Ar' (20) and {K(18C6)}[Zn(OCRMe^F2)3], with R = Ph (21) were also prepared and characterized by X-ray crystallography and multinuclear NMR

Room Temperature Stable Organocuprate Copper(III) Complex

The paramagnetic trigonal-planar copper complexes {K­(18C6)}­[Cu^II(OC­(CH₃)­(CF₃)₂)₃] (<b>2</b>) and K­[Cu^II(OC­(C₆H₅)­(CF₃)₂)₃] (<b>3</b>) have been prepared and characterized, including X-ray crystallography, in 61% and 3% yields, respectively. The latter complex does not form preferentially, because CuBr₂ and KOC­(C₆H₅)­(CF₃)₂)₃ also form the diamagnetic complexes {K­(18C6)}­[K₂{Cu^I(OC­(C₆H₅)­(CF₃)₂)₂}₃] (<b>4</b>) and {K­(18C6)}­[Cu^III(OC­(C₆H₄)­(CF₃)₂)₂] (<b>5</b>). These species were characterized by X-ray crystallography, UV–vis spectroscopy, ¹H, ¹³C­{¹H}, and ¹⁹F­{¹H} NMR spectroscopy, and elemental analysis. The unique organocuprate Cu­(III) species with {O₂C₂} coordination was formed by ortho metalation of two phenyl rings, resulting in <i>trans</i>-{O₂C₂} coordination of Cu­(III), and is stable at room temperature in the solid state and in dark solutions of THF

Room Temperature Stable Organocuprate Copper(III) Complex

The paramagnetic trigonal-planar copper complexes {K­(18C6)}­[Cu^II(OC­(CH₃)­(CF₃)₂)₃] (<b>2</b>) and K­[Cu^II(OC­(C₆H₅)­(CF₃)₂)₃] (<b>3</b>) have been prepared and characterized, including X-ray crystallography, in 61% and 3% yields, respectively. The latter complex does not form preferentially, because CuBr₂ and KOC­(C₆H₅)­(CF₃)₂)₃ also form the diamagnetic complexes {K­(18C6)}­[K₂{Cu^I(OC­(C₆H₅)­(CF₃)₂)₂}₃] (<b>4</b>) and {K­(18C6)}­[Cu^III(OC­(C₆H₄)­(CF₃)₂)₂] (<b>5</b>). These species were characterized by X-ray crystallography, UV–vis spectroscopy, ¹H, ¹³C­{¹H}, and ¹⁹F­{¹H} NMR spectroscopy, and elemental analysis. The unique organocuprate Cu­(III) species with {O₂C₂} coordination was formed by ortho metalation of two phenyl rings, resulting in <i>trans</i>-{O₂C₂} coordination of Cu­(III), and is stable at room temperature in the solid state and in dark solutions of THF

Serine–Lysine Peptides as Mediators for the Production of Titanium Dioxide: Investigating the Effects of Primary and Secondary Structures Using Solid-State NMR Spectroscopy and DFT Calculations

A biomimetic approach to the formation of titania (TiO₂) nanostructures is desirable because of the mild conditions required in this form of production. We have identified a series of serine–lysine peptides as candidates for the biomimetic production of TiO₂ nanostructures. We have assayed these peptides for TiO₂-precipitating activity upon exposure to titanium bis­(ammonium lactato)­dihydroxide and have characterized the resulting coprecipitates using scanning electron microscopy. A subset of these assayed peptides efficiently facilitates the production of TiO₂ nanospheres. Here, we investigate the process of TiO₂ nanosphere formation mediated by the S–K peptides KSSKK- and SKSK₃SKS using one-dimensional and two-dimensional solid-state NMR (ssNMR) on peptide samples with uniformly ¹³C-enriched residues. ssNMR is used to assign ¹³C chemical shifts (CSs) site-specifically in each free peptide and TiO₂-embedded peptide, which are used to derive secondary structures in the neat and TiO₂ coprecipitated states. The backbone ¹³C CSs are used to assess secondary structural changes undergone during the coprecipitation process. Side-chain ¹³C CS changes are analyzed with density functional theory calculations and used to determine side-chain conformational changes that occur upon coprecipitation with TiO₂ and to determine surface orientation of lysine side chains in TiO₂–peptide composites

Structural and Electronic Properties of Old and New A₂[M(pin^F)₂] Complexes

Seven new homoleptic complexes of the form A₂[M­(pin^F)₂] have been synthesized with the dodecafluoropinacolate (pin^F)^2– ligand, namely (Me₄N)₂[Fe­(pin^F)₂], <b>1</b>; (Me₄N)₂[Co­(pin^F)₂], <b>2</b>; (ⁿBu₄N)₂[Co­(pin^F)₂], <b>3</b>; {K­(DME)₂}₂[Ni­(pin^F)₂], <b>4</b>; (Me₄N)₂[Ni­(pin^F)₂], <b>5</b>; {K­(DME)₂}₂[Cu­(pin^F)₂], <b>7</b>; and (Me₄N)₂[Cu­(pin^F)₂], <b>8</b>. In addition, the previously reported complexes K₂[Cu­(pin^F)₂], <b>6</b>, and K₂[Zn­(pin^F)₂], <b>9</b>, are characterized in much greater detail in this work. These nine compounds have been characterized by UV–vis spectroscopy, cyclic voltammetry, elemental analysis, and for paramagnetic compounds, Evans method magnetic susceptibility. Single-crystal X-ray crystallographic data were obtained for all complexes except <b>5</b>. The crystallographic data show a square-planar geometry about the metal center in all Fe (<b>1</b>), Ni (<b>4</b>), and Cu (<b>6</b>, <b>7</b>, <b>8</b>) complexes independent of countercation. The Co species exhibit square-planar (<b>3</b>) or distorted square-planar geometries (<b>2</b>), and the Zn species (<b>9</b>) is tetrahedral. No evidence for solvent binding to any Cu or Zn complex was observed. Solvent binding in Ni can be tuned by the countercation, whereas in Co only strongly donating Lewis solvents bind independent of the countercation. Indirect evidence (diffuse reflectance spectra and conductivity data) suggest that <b>5</b> is not a square-planar compound, unlike <b>4</b> or the literature K₂[Ni­(pin^F)₂]. Cyclic voltammetry studies reveal reversible redox couples for Ni­(III)/Ni­(II) in <b>5</b> and for Cu­(III)/Cu­(II) in <b>8</b> but quasi-reversible couples for the Fe­(III)/Fe­(II) couple in <b>1</b> and the Co­(III)/Co­(II) couple in <b>2</b>. Perfluorination of the pinacolate ligand results in an increase in the central C–C bond length due to steric clashes between CF₃ groups, relative to perhydropinacolate complexes. Both types of pinacolate complexes exhibit O–C–C–O torsion angles around 40°. Together, these data demonstrate that perfluorination of the pinacolate ligand makes possible highly unusual and coordinatively unsaturated high-spin metal centers with ready thermodynamic access to rare oxidation states such as Ni­(III) and Cu­(III)