Thiolane Analysis

PPV, which is the abbreviated term for phenylenevinylene, has light emitting properties since it has a large conjugated system. This organic molecule is possible to be formed from dichloro-para-xylene which then reacts with methanol and thiolane. The nucleophile would be the thiolane. A good leaving group in this case would be chlorine. After thiolane attacks, it results with dithiolane-xylene. The second step is reaction with sodium hydroxide. The hydroxide it used for deprotonation upon the substituted methyl group. This creates a carbocation. The carbocation attacks another similar monomer in which the thiolane is the leaving group. This creates two thiolanes on one monomer and one thiolane on the other monomer. The monomer with two thiolanes loses one of the thiolanes to form a double bond near the monomer with one thiolane. The mono with one thiolane gets deprotonated and continues the chain. This cannot work without heat. Chlorine itself is not a strong enough base for deprotonation. However, chlorine is a good leaving group, so a Sn2 or Sn1 mechanism can work. The chlorine leaving thus creates a carbocation, but the carbocation can have resonance stability. These
steps are not strenuous so it is possible for mass production which makes phenylenevinylene affordable.
PPV can also be synthesized through reaction of xylene with NBS and Br2. This creates dibromo-xylene. Dibromo-xylene reacts with a halogen such as Chlorine from AlCl3. This substitutes the benzene ring so it contains EWG, or election withdrawing groups. EWG are needed to create specific products. The halogens would be on the ortho-para positions.
Phenylenevinylene is one of many organic polymers that are useful for light emitting diodes. These diodes are functional through organic polymers’ conjugated pi system. Pi electrons can increase orbitals. This means the energy gap between orbitals will decrease. That is why organic polymers can have their highest occupied molecular orbital rise to the next orbital. When the electron relaxes, it will drop down to the previous orbital. This will release light depending on the energy gap. Smaller gaps equal to radio waves and larger gaps near gamma rays. Nearing visible light, monomers will experience more conjugation which will decrease the energy gap. This means there will be a shift from Red to Blue and vice versa.
Acquiring same coloring from the visible color spectrum follows the same theory.
Phenylenevinylene show light in the green region. Phenylenevinylene has simple carbon chains which entitles weak electron donation groups. This means shifting color to red would happen if an electron donation group is added which entitles the monomer to have a smaller orbital gap. Smaller orbital gaps have lower wavelengths. An example would be with BEH-PPV. BEH-PPV also produces green light such as PPV. BEH-PPV also has a simple carbon structures with basic carbon chains. With BEH-PPV, shifting to blue would entitle an electron withdrawing group to be added to the monomer. The strength of the electron withdrawing group or electron donating group is what determines the distance of how far the blue or red shift will
be.
OLED would be less sturdy than inorganic LED. This is due to the structure of a polymer not comparing to an inorganic structure. An inorganic structure can be enhanced to be sturdy. OLED requires a specific pattern and specific structure for it to be functional. This means OLED are not as viable as inorganic LED. OLEDs are also more reactive comparing to inorganic LEDs. This is shown if orange juice is spilled upon a phone. The orange juice can react with the alkene within the benzene. This entitles the water molecule to attack the carbocation. Attacking the carbocation changes the light emission by decreasing conjugation. This would most likely not occur though. Polymers do not dissolve efficiently within water since it is nonpolar.