Synthesis and Characterization of Zn(Tpp) and Cu(Tpp)

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  • Topic: Porphyrin, Chemistry, Supramolecular chemistry
  • Pages : 10 (3054 words )
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  • Published : April 13, 2013
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Synthesis and Characterization of Zn(TPP) and Cu(TPP) Complexes

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Project Summary The overall goal of the project is to synthesize two metalloporhyrins, (Tetraphenylporphyrinato)zinc(II) and (Tetraphenylporphyrinato)copper(II). Because metalloporphyrins occur naturally in hemoglobin and chlorophyll, their study has implications in synthesizing human blood as well as utilizing its ability to convert visible light to energy. In addition to these two applications, metalloporhyrins are utilized in supramolecular studies, are being researched for potential photodynamic therapy, and are used in building electronics on the molecular scale. While Zinc and Copper may not be the basis of chlorophyll or hemoglobin, by studying any metalloporhyrin, one can gain a greater understanding of the scientific applications surrounding Tetraphenylporphyrin (TPP). In order to generate TPP, the group has elected to use the procedure outlined in Bozak & Hill. This requires adding equal parts of distilled pyrrole and reagent grade benzaldehyde together in a round bottom flask in propionic acid. This solution is then refluxed for about 30 minutes and the precipitate is dried by suction filtration. This product will be analyzed and classified by UV-Vis, FT-IR, and H1 FT-NMR. Once the product is determined to be TPP, it will be reacted with ZnCl2 and CuCl2 separately. An excess amount of the metal chloride will be added to a round bottom flask, along with the TPP, and will be refluxed for 30 minutes in the presence of DMF. The resulting precipitates will then be dried by suction filtration and classified using the same methods as the TPP classification.

Project Description Porphyrin-based compounds and complexes have been studied by experts from a wide range of scientific disciplines, including material science, biomedical science, organic chemistry and supramolecular chemistry. Porphyrin (Figure 1) belongs to the highly symmetrical D4h point group and possesses an extensively conjugated and easily adaptable structure, making it an interesting subject for chemical and physical experiments as well as an exceptionally effective starting material for the synthesis of a wide range of industrially useful compounds. Specifically, the highly conjugated two-dimensional pi-system and stable structure of porphyrin compounds allow them to act as highly efficient molecular photo-absorbers and electron transporters. The adaptable nature of the porphyrin structure also allows for fine-tuning of its photochemical, photophysical, and redox properties through the addition of metal ions and other substituents.1 Tetraphenylporphyrin (TPP), shown in Figure 2, retains the D 4h symmetry of porphyrin, but increases both the size of the molecule and the amount of conjugation present.

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Figure 1: Porphyrin (http://www.chemistrydaily.com/chemistry/Porphyrin) Figure 2: Tetraphenylporphyrin (TPP) (http://www.scbt.com/datasheet-215304-meso-tetraphenylporphyrin.html) Naturally occurring porphyrin complexes serve important roles in biological systems. For example, hemoglobin contains an iron-porphyrin complex which cooperatively binds dioxygen, thus allowing it to transport oxygen through the bloodstream. The porphyrin ring influences the stability of the oxygen-iron bonding, and plays a major role in the cooperativity of the enzyme binding sites. 2 In chlorophyll, a magnesium-porphyrin complex absorbs photonic energy to excite a pi electron and then acts as a charge separator to initiate the process of photosynthesis.3 The stable structure and electronic properties of porphyrin allow it to serve these important biological functions. In the biomedical sciences, the porphyrin-based compound hematoporphyrin has become commercially available as a photodynamic chemotherapy agent.4 Photodynamic therapy involves the localization of photosensitive molecules to tumorous tissues and the subsequent activation of those molecules via irradiation with light of a specific...
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