Browsing by Subject "Porphycenes"
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Item [pi]-metal complexes of i-propyldinaphthoporphycene(2011-08) Vargas-Zuniga, Gabriela Idania; Sessler, Jonathan L.; Bielawski, ChristopherPorphycenes have attracted attention for their ability to stabilize complexes with a wide range of metal cations. Coordination compounds of these macrocycles are endowed with of specific chemical, optical, electronic, spectroscopic and photochemical properties,1-8 such as, strong absoptions in the red region of the UV-vis spectrum. These characteristics have been used in the study of protein mimicry,9, 10 photodynamic therapy (PDT)11-16 and materials chemistry17, 18 The fusion of bipyrrolic entities with aromatic rings could led to a change in the photophysical properties of porphycenes, and could give rise to nonlinear optical (NLO) behavior.19 Taken in concert, these possibilities provides an incentive to study metal complexes of new porphycenes. With that goal in mind, presented here is the synthesis and the spectroscopic and voltamperometric analyses of four metollocene complexes of a relatively new annulated porphycenes, namely i-propyldinaphthoporphycene. Chapter 1 of this thesis provides a brief introduction into porphycenes and porphyrins as well as complexes prepared from these macrocycles. Because it relates more closely to the research described in this thesis, the emphasis will be on peripherally substituted and directly π-metallated porphyrin-like macrocycles. Annulated porphycenes and their metal complexes display geometric and optical features that differ from those of normal porphycenes. Chapter 2 details the coordination compounds of annulated porphycenes, as well as some of their optical and redox features. This chapter also summarizes the current synthesis of dinaphthoporphycenes, while detailing efforts by other authors to coordinate transition metals to dinaphthoporphycenes, which culminated in the preparation of the first nickel(II) complex known so far with this ligand. It was recently found that the electronic properties of porphycenes change from those of an electron donor to those of an electron acceptor when the RuCp* (Cp*: pentamethylcyclopentadienyl) fragment is coordinated to the “π-face” of the macrocycle. This finding, discovered using so-called etioporphycenes, motivated the author to explore the metal complexation chemistry of i-porpyldinaphthoporphycene. This led to the synthesis of four metalloporphycenes are described in Chapter 3. Here, the coordination of the [M(Cp*)]n+ (M = Ru, Ir and Rh) fragments to the π-electron framework was established by analytical, and structural means. Thus, this chapter provides of a description of the spectroscopic, structural and voltamperometric features of these complexes.Item Synthesis, anion binding, and photophysiscal properties in polypyrrolic systems(2013-12) Vargas-Zúñiga, Gabriela Idania; Sessler, Jonathan L.Anion binding has emerged as an important field of study due to the role that anionic species play in nature. As a consequence, considerable effort has been focused on the generation of anion receptors. These receptors have been designed to recognize anions through interactions, such as hydrogen bonding, donor-acceptor, and hydrophofic effects, in order to achieve higher sensitivity and selectivity. Another approach involves ion pair recognition, wherein the anions and cations are bound to the same system. Specifically, receptors bearing both hydrogen bonding donor and cation coordination sites have been of great interest as systems that lead to anion recognition and enhanced anion selectivities. Chapter 1 of this dissertation describes efforts to develop systems on the basis of modified Schiff-base calixpyrroles. This modification was achieved by incorporating a “strap” across the macrocycle to produce the so-called strapped Schiff-base calixpyrroles. The strap bearing amides are known to act as hydrogen bonding donors that can isolate the binding site from the medium. On the other hand, Schiff-base calixpyrroles have been widely studied as multidentate ligands for metal cation coordination. Therefore, the synthetic combination of these two moieties might provide a system wherein an ion pair complex is formed. Strapped Schiff-base calixpyrrole palladium complex were found to bind selectively cyanide anions. The effects of direct substitution on one meso position on the optical and photophysical properties of porphycenes was recently found to be dependent of the electronic properties of the substituten (e.g., electron donor or electron withdrawing group). However, the effects on the electronic and optical properties properties as a result of substitution through a conjugated spacer are as yet unknown. This led to the synthesis of four meso substituted etioporphycenes, which are described in Chapter 2. Here, the substitution through an ethenyl group was stablished by analytical and structural means. This chapter provides of a description of the spectroscopic, structural and voltamperometric features of these compounds. Experimental procedures and characterization data are reported in Chapter 3.