Degree Discipline

Language

Synthesis and Characterization of Platinum(II)(2-(9-anthracenylylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione)(dichloride), Platinum(II)(2-(9-anthracenylylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione(maleonitriledithiolate), and Platinum(II)(4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione)(4-Methyl-1,2-benzene dithiol) (open access)

Synthesis and Characterization of Platinum(II)(2-(9-anthracenylylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione)(dichloride), Platinum(II)(2-(9-anthracenylylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione(maleonitriledithiolate), and Platinum(II)(4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione)(4-Methyl-1,2-benzene dithiol)

Substitution of the 1,5-cyclooctadiene (cod) ligand in PtCl2(cod) (1) by the diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) yields PtCl2(bpcd) (2). Knoevenagel condensation of 2 with 9-anthracenecarboxaldehyde leads to the functionalization of the bpcd ligand and formation of the corresponding 2-(9-anthracenylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (abpcd) substituted compound PtCl2(abpcd) (3), which is also obtained from the direct reaction of 1 with the abpcd ligand in near quantitative yield. The reaction of 3 with disodium maleonitriledithiolate (Na2mnt) affords the chelating dithiolate compound Pt(mnt)(abpcd) (4). The reaction of PtCl2(bpcd) (2) with 4-methyl-1,2-benzene dithiol under basic conditions affords Pt(tdt)(bpcd) (5). Compounds 2-5 have been fully characterized in solution by IR and NMR spectroscopies (1H and 31P), and their molecular structures established by X-ray crystallography. The electrochemical properties of 2‑5 have examined by cyclic voltammetry, and the nature of the HOMO and LUMO levels in systems 2-4 has been established by MO calculations at the extended Hückel level, the results of which are discussed with respect to electrochemical data and related diphosphine derivatives. In addition the new compounds 2-5 have been isolated by column chromatography and characterized by IR, UV-Vis spectroscopy.
Date: December 2009
Creator: Hunt, Sean W.
System: The UNT Digital Library
Phosphorescent Emissions of Coinage Metal-Phosphine Complexes: Theory and Photophysics (open access)

Phosphorescent Emissions of Coinage Metal-Phosphine Complexes: Theory and Photophysics

The major topics discussed are all relevant to the bright phosphorescent emissions of coinage metal complexes (Cu(I), Ag(I) and Au(I)) with an explanation of the theoretical background, computational results and ongoing work on the application in materials and optoelectronic devices. Density functional computations have been performed on the majority of the discussed complexes and determined that the most significant distortion that occurs in Au(I)-phosphine complexes is a near and beyond a T-shape within the P-Au-P angle when the complexes are photoexcited to the lowest phosphorescent excited state. The large distortion is experimentally qualified with the large Stokes' shift that occurs between the excitation and emission spectra and can be as large as 18 000 cm-1 for the neutral Au(I) complexes. The excited state distortion has been thoroughly investigated and it is determined that not only is it pertinent to the efficient luminescence but also for the tunability in the emission. The factors that affect tunability have been determined to be electronics, sterics, rigidity of solution and temperature. The luminescent shifts determined from varying these parameters have been described systematically and have revealed emission colors that span the entire visible spectrum. These astounding features that have been discovered within studies of …
Date: December 2009
Creator: Sinha, Pankaj
System: The UNT Digital Library
Electrochemical Deposition of Zinc-Nickel Alloys in Alkaline Solution for Increased Corrosion Resistance. (open access)

Electrochemical Deposition of Zinc-Nickel Alloys in Alkaline Solution for Increased Corrosion Resistance.

The optimal conditions for deposition of zinc-nickel alloys onto stainless steel discs in alkaline solutions have been examined. In the past cadmium has been used because it shows good corrosion protection, but other methods are being examined due to the high toxicity and environmental threats posed by its use. Zinc has been found to provide good corrosion resistance, but the corrosion resistance is greatly increased when alloyed with nickel. The concentration of nickel in the deposit has long been a debated issue, but for basic solutions a nickel concentration of 8-15% appears optimal. However, deposition of zinc-nickel alloys from acidic solutions has average nickel concentrations of 12-15%. Alkaline conditions give a more uniform deposition layer, or better metal distribution, thereby a better corrosion resistance. Although TEA (triethanolamine) is most commonly used to complex the metals in solution, in this work I examined TEA along with other complexing agents. Although alkaline solutions have been examined, most research has been done in pH ≥ 12 solutions. However, there has been some work performed in the pH 9.3-9.5 range. This work examines different ligands in a pH 9.3-9.4 range. Direct potential plating and pulse potential plating methods are examined for optimal platings. The …
Date: December 2009
Creator: Conrad, Heidi A.
System: The UNT Digital Library