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Karan Aryanpour - One of the best experts on this subject based on the ideXlab platform.
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Theory of Singlet Fission in Polyenes, Acene Crystals, and Covalently Linked Acene Dimers
The Journal of Physical Chemistry C, 2015Co-Authors: Karan Aryanpour, Alok Shukla, Sumitendra MazumdarAbstract:We report quadruple configuration interaction calculations within the extended Pariser–Parr–Pople Hamiltonian on the excited states of aggregates of Polyenes, crystalline acenes, and covalently linked dimers of acene molecules. We determine the precise energy orderings and analyze the cluster wave functions in order to arrive at a comprehensive physical understanding of singlet fission in these diverse families of materials. Our computational approach allows us to retain a very large number of basis states and thereby obtain the correct relative energy orderings of one electron–one hole Frenkel and charge-transfer excitons versus intra- and intermolecular two electron–two hole triplet–triplet excited states. We show that from the energy orderings it is possible to understand the occurrence of singlet fission in Polyene and acene crystals, as well as its near total absence in the covalently linked acene dimers. As in the acene crystals, singlet fission in the Polyenes is a multichromophoric phenomenon, wit...
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Theory of singlet fission in Polyenes, acene crystals, and covalently linked acene dimers
Journal of Physical Chemistry C, 2015Co-Authors: Karan Aryanpour, Alok Shukla, Sumit MazumdarAbstract:We report quadruple configuration interaction calculations within the extended Pariser$-$Parr$-$Pople Hamiltonian on the excited states of aggregates of Polyenes, crystalline acenes, and covalently linked dimers of acene molecules. We determine the precise energy orderings and analyze the cluster wave functions in order to arrive at a comprehensive physical understanding of singlet fission in these diverse families of materials. Our computational approach allows us to retain a very large number of basis states and thereby obtain the correct relative energy orderings of one electron$-$one hole Frenkel and charge-transfer excitons versus intra- and intermolecular two electron$-$two hole triplet$-$triplet excited states. We show that from the energy orderings it is possible to understand the occurrence of singlet fission in Polyene and acene crystals, as well as its near total absence in the covalently linked acene dimers. As in the acene crystals, singlet fission in the Polyenes is a multichromophoric phenomenon, with the well-known 2$^1$A$_g^-$ playing no direct role. Intermolecular charge-transfer is essential for singlet fission in both acenes and Polyenes, but because of subtle differences in the natures and orderings of the aggregate excited states, the mechanisms of singlet fission are slightly different in the two classes. We are thus able to give qualitative physical reasoning for the slower singlet fission in the Polyenes, relative to that in crystalline pentacene. Our work also gives new insight into the complex exciton dynamics in tetracene crystals, which has been difficult to understand theoretically. Our large-scale many-body calculations provide us with the ability to understand the qualitative differences in the singlet fission yields and rates between different classes of $\pi$-conjugated materials.
Sumit Mazumdar - One of the best experts on this subject based on the ideXlab platform.
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Theory of singlet fission in Polyenes, acene crystals, and covalently linked acene dimers
Journal of Physical Chemistry C, 2015Co-Authors: Karan Aryanpour, Alok Shukla, Sumit MazumdarAbstract:We report quadruple configuration interaction calculations within the extended Pariser$-$Parr$-$Pople Hamiltonian on the excited states of aggregates of Polyenes, crystalline acenes, and covalently linked dimers of acene molecules. We determine the precise energy orderings and analyze the cluster wave functions in order to arrive at a comprehensive physical understanding of singlet fission in these diverse families of materials. Our computational approach allows us to retain a very large number of basis states and thereby obtain the correct relative energy orderings of one electron$-$one hole Frenkel and charge-transfer excitons versus intra- and intermolecular two electron$-$two hole triplet$-$triplet excited states. We show that from the energy orderings it is possible to understand the occurrence of singlet fission in Polyene and acene crystals, as well as its near total absence in the covalently linked acene dimers. As in the acene crystals, singlet fission in the Polyenes is a multichromophoric phenomenon, with the well-known 2$^1$A$_g^-$ playing no direct role. Intermolecular charge-transfer is essential for singlet fission in both acenes and Polyenes, but because of subtle differences in the natures and orderings of the aggregate excited states, the mechanisms of singlet fission are slightly different in the two classes. We are thus able to give qualitative physical reasoning for the slower singlet fission in the Polyenes, relative to that in crystalline pentacene. Our work also gives new insight into the complex exciton dynamics in tetracene crystals, which has been difficult to understand theoretically. Our large-scale many-body calculations provide us with the ability to understand the qualitative differences in the singlet fission yields and rates between different classes of $\pi$-conjugated materials.
Sumitendra Mazumdar - One of the best experts on this subject based on the ideXlab platform.
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Theory of Singlet Fission in Polyenes, Acene Crystals, and Covalently Linked Acene Dimers
The Journal of Physical Chemistry C, 2015Co-Authors: Karan Aryanpour, Alok Shukla, Sumitendra MazumdarAbstract:We report quadruple configuration interaction calculations within the extended Pariser–Parr–Pople Hamiltonian on the excited states of aggregates of Polyenes, crystalline acenes, and covalently linked dimers of acene molecules. We determine the precise energy orderings and analyze the cluster wave functions in order to arrive at a comprehensive physical understanding of singlet fission in these diverse families of materials. Our computational approach allows us to retain a very large number of basis states and thereby obtain the correct relative energy orderings of one electron–one hole Frenkel and charge-transfer excitons versus intra- and intermolecular two electron–two hole triplet–triplet excited states. We show that from the energy orderings it is possible to understand the occurrence of singlet fission in Polyene and acene crystals, as well as its near total absence in the covalently linked acene dimers. As in the acene crystals, singlet fission in the Polyenes is a multichromophoric phenomenon, wit...
Alok Shukla - One of the best experts on this subject based on the ideXlab platform.
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Theory of Singlet Fission in Polyenes, Acene Crystals, and Covalently Linked Acene Dimers
The Journal of Physical Chemistry C, 2015Co-Authors: Karan Aryanpour, Alok Shukla, Sumitendra MazumdarAbstract:We report quadruple configuration interaction calculations within the extended Pariser–Parr–Pople Hamiltonian on the excited states of aggregates of Polyenes, crystalline acenes, and covalently linked dimers of acene molecules. We determine the precise energy orderings and analyze the cluster wave functions in order to arrive at a comprehensive physical understanding of singlet fission in these diverse families of materials. Our computational approach allows us to retain a very large number of basis states and thereby obtain the correct relative energy orderings of one electron–one hole Frenkel and charge-transfer excitons versus intra- and intermolecular two electron–two hole triplet–triplet excited states. We show that from the energy orderings it is possible to understand the occurrence of singlet fission in Polyene and acene crystals, as well as its near total absence in the covalently linked acene dimers. As in the acene crystals, singlet fission in the Polyenes is a multichromophoric phenomenon, wit...
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Theory of singlet fission in Polyenes, acene crystals, and covalently linked acene dimers
Journal of Physical Chemistry C, 2015Co-Authors: Karan Aryanpour, Alok Shukla, Sumit MazumdarAbstract:We report quadruple configuration interaction calculations within the extended Pariser$-$Parr$-$Pople Hamiltonian on the excited states of aggregates of Polyenes, crystalline acenes, and covalently linked dimers of acene molecules. We determine the precise energy orderings and analyze the cluster wave functions in order to arrive at a comprehensive physical understanding of singlet fission in these diverse families of materials. Our computational approach allows us to retain a very large number of basis states and thereby obtain the correct relative energy orderings of one electron$-$one hole Frenkel and charge-transfer excitons versus intra- and intermolecular two electron$-$two hole triplet$-$triplet excited states. We show that from the energy orderings it is possible to understand the occurrence of singlet fission in Polyene and acene crystals, as well as its near total absence in the covalently linked acene dimers. As in the acene crystals, singlet fission in the Polyenes is a multichromophoric phenomenon, with the well-known 2$^1$A$_g^-$ playing no direct role. Intermolecular charge-transfer is essential for singlet fission in both acenes and Polyenes, but because of subtle differences in the natures and orderings of the aggregate excited states, the mechanisms of singlet fission are slightly different in the two classes. We are thus able to give qualitative physical reasoning for the slower singlet fission in the Polyenes, relative to that in crystalline pentacene. Our work also gives new insight into the complex exciton dynamics in tetracene crystals, which has been difficult to understand theoretically. Our large-scale many-body calculations provide us with the ability to understand the qualitative differences in the singlet fission yields and rates between different classes of $\pi$-conjugated materials.
Mitchell P. Croatt - One of the best experts on this subject based on the ideXlab platform.
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Palladium-Catalyzed Chemoselective Protodecarboxylation of Polyenoic Acids.
Organic Letters, 2018Co-Authors: Mohammed H. Al-huniti, Mark A. Perez, Matthew K. Garr, Mitchell P. CroattAbstract:Conditions for the first palladium-catalyzed chemoselective protodecarboxylation of polyenoic acids to give the desired Polyenes in good yields are presented. The reactions proceed under mild conditions using either a Pd(0) or Pd(II) catalyst and tolerate a variety of aryl and aliphatic substitutions. Unique aspects of the reaction include the requirement of phosphines, water, and a Polyene adjacent to the carboxylic acid.
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Palladium-Catalyzed Chemoselective Protodecarboxylation of Polyenoic Acids
2018Co-Authors: Mohammed H. Al-huniti, Mark A. Perez, Matthew K. Garr, Mitchell P. CroattAbstract:Conditions for the first palladium-catalyzed chemoselective protodecarboxylation of polyenoic acids to give the desired Polyenes in good yields are presented. The reactions proceed under mild conditions using either a Pd(0) or Pd(II) catalyst and tolerate a variety of aryl and aliphatic substitutions. Unique aspects of the reaction include the requirement of phosphines, water, and a Polyene adjacent to the carboxylic acid
