Porphyrin Research at the Evergreen State College: The Synthesis, Separation, Isolation and Characte

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Porphyrin Research at the Evergreen
State CollegeThe Synthesis, Separation,
Isolation and Characterization of Di-functional
meso-substituted Porphyrins

• (An Advancement toward Solar Energy Harvesting
  Technologies)

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Introduction

• The process of photosynthesis has interested
  humanity for eons. It is arguably the most
  important biological process on earth and is
  responsible for a large portion of our current
  energy needs.

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Structural Formulas

• .

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Chlorophyll

• In plants, the green pigment chlorophyll absorbs
  light energy. Chlorophyll is a porphyrin molecule
  that resides in the thylakoid membrane of the
  chloroplast. And

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Porphyrins

• Natural pigments containing a fundamental
  skeleton of four pyrrole nuclei united through
  the alpha positions by four methine groups to
  form a macrocylic structure
• ( IUPAC Compendium of Chemical Terminology 2nd
  Edition)

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Photovoltaic cell

• When sunlight strikes the surface of these cells
  an electrical field provides both momentum and
  direction to electrons that results in a flow of
  current.
• Image WWW.Altenergy.com

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Photovoltaic cell

• These cells can be connected electrically in
  series and/or parallel circuits to produce
  higher, currents, voltage and power levels.
• Image WWW.Altenergy.com

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Gratzell cell

• A proposed design
• for a solar cell which
• utillizes porphyrins.
• Image WWW.Chem.pdx.edu

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Synthesis

• For the initial synthesis of these porphyrins,
  the Rothemund Method was utilized. This technique
  was first developed during the 1930s and later
  improved upon in the 70s by the Adler research
  group at the University of Pennsylvania.

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Synthesis

• For the initial synthesis of these porphyrins,
  the Rothemund Method was utilized. This technique
  was first developed during the 1930s and later
  improved upon in the 70s by the Adler research
  group at the University of Pennsylvania.

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The synthesis of meso-Tri(Tolyl)
Mono(4-carboxyphenyl) Porohyrin

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Isolation

• When two types of aldehydes are used, this
  reaction mechanism will produce five different
  structural isomers.

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Column Chromatography

• The technique of column chromatography was
  developed in 1906 by the Italian-born Russian
  botanist Mikhail Tswett. During the process, a
  mixture of compounds is dissolved into a liquid
  phase and allowed to flow through a column of
  powdered calcium carbonate in a vertical glass
  tube.

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Isolation

• The roto-vap, or rotary evaporator, is a device
  that allows a liquid to be evaporated in a
  controlled manner

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NMR Spectroscopy

• NMR is a technique that was developed in 1945 by
  American physicists Felix Bloch and Edward Mills
  Purcell.

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• This technique is based on the principle that a
  spinning photon generates a magnetic field.

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• During NMR, a substance is placed in a strong
  magnetic field causing the protons to align with
  the stronger field in a lower energy state

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• A radio wave is passed through the substance
  supplies the resonance frequency needed to excite
  the protons to the higher energy state

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• The use of NMR spectroscopy for structural
  determination arises because protons in a
  substance experience slightly different magnetic
  fields.

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Example of a NMR Spectrum

• meso-Tetra (Tolyl) Porphyrin NMR spectrum

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UV-Vis Spectroscopy

• When a sample is irradiated with UV light, it
  causes the promotion of an electron from a ground
  electronic state to an excited electronic state
• Image WWW.sci/lib/Upenn.edu

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• Absorption is described by the log of radiant
  power entering the sample, P0, divided by the
  radiant power leaving the sample, P, and is
  directly proportional to the path length, l, and
  the concentration, c, of the absorbing species
  multiplied by, e, a constant of proportionality,
  called the absorbtivity or epsilon value.

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• Because of the way absorption is defined, The
  total power absorbed by a molecule in the Uv-Vis
  region of the EM spectrum can be calculated by
  tacking the integral of the derivative of the
  power absorbed with respect to the change in
  wavelength and multiplying it by the change in
  wavelength.

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Example of a UV-Vis Spectrum

• meso-Tetra (Tolyl) Porphyrin Uv-Vis spectrum

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Other Applications of Porphyrins

• 1. Current electronics research is focused on
  producing computers that are faster and more
  compact (The intriguing possibility of making
  electronic components from single molecules or
  small groups of molecules is becoming a large
  area of research. Another very active area of
  research is computers that use light, rather than
  electrons, as the medium for carrying
  information. In principle, light-based computers
  have several advantages over traditional designs)
  Proffesor Deven Gust of ASU
• Image WWW.ArmyTechnology.com

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Other Applications of Porphyrins

• 2. Light has a very high energy content, and
  cause serious damage to living organisms. For
  example, sunlight absorbed by photosynthetic
  chlorophyll will sometimes cause tissue damage in
  plants. Furthermore, It has been shown that
  certain porphyrins will localize in cancerous
  tumor tissue. Illumination of this area results
  in photochemical damage which destroys the tumor
  while leaving surrounding tissue undamaged.
• Image WWW.Cancerresearch.com

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Thanks