Invention:
This invention is an efficient, green route for oxidizing simple pyrenes without any metal-mediated catalyst or reagent, with desired product in high yield. This direct oxidation method may be used to synthesize organic semi-conductors for use as photovoltaics, transistors, LEDs while avoiding poor yields, product impurities, and expensive work-up. This method has been demonstrated for selectively oxidizing the K-region of pyrenes using a meta-free oxidizing agent to produce a pyrene 4,5-dione and/or a pyrene 4,5,9,10-tetraone compounds.
Background:
Pyrene compounds are polycyclic aromatic hydrocarbon (PAH) molecules that are used widely in various applications including, but not limited to, use as fluorescent probes and starting materials for producing various organic electronic components such as organic light emitting diodes (OLEDs), organic field effect transistors (OFETs), and organic photovoltaics (OPVs). Chemical modifications of pyrenes through a variety of methods enable their incorporation into more complex chemical systems make them useful starting materials for larger organic semiconductors as they enable the extension of the π- conjugated system via simple condensation reactions with ortho-diamines. This strategy enables the synthesis of imine rich N-heteroacene chains known as pyrene-fused pyrazaacenes (PPAs) that exhibit a wide range tunable semiconducting properties (p-type to n-type) unlike their nitrogen-free acene counterparts. Owing to the two Clar sextets provided per pyrene subunit, PPAs are air-stable even above 500C. Even though ortho-quinones of pyrenes are useful starting materials for the synthesis of PPAs and other organic semi-conductors, their synthesis via direct oxidation of pyrene derivatives have been difficult due to lack of selectivity to desired products, even with expensive transition metal catalysts, as well as the expense and loss of product during purification due to formation of tarry residue. Moreover, use of these transition metals results in wastes that are environmentally toxic and requires additional cost and time for disposal.
Applications:
- Organic photovoltaics
- Organic field effect transistors (OFETs)
- Organic light emitting diodes (OLEDs)
Advantages:
- Synthesis route via pyrene oxidation
- No metal catalyst
- High yield
- Green chemistry
- Air stable
