Shrinwantu Pal - Role of Dipolar Interactions in Fine-Tuning the Linear and Nonlinear Optical Responses in Porphyrins

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      Publication Details (including relevant citation   information):

      The variation in the ground-state dipole moment, polarizability   and the 1st hyperpolarizability for non-chelated   porphyrins are studied with increase in the inter-dipolar angles   between the pyrrole rings. The different dipolar orientations are   realized through twisting of one of the ring along the porphyrin   plane. Computations performed on both conformational and   configurational isomers of porphyins lead to a variety of   structures. For the conformational distortions, the dipole-moment   (μ), the polarizability (α) and the 1st  hyperpolarizabilities (β) increase with increase in the   distortions. This is understood on the basis of a simple   excitonic picture wherein the splitting due to dipolar   interactions reduces with increase in the distortions which   effectively reduces the optical gap for the system. The   computations reveal that dihedral twists within the conventional   porphyrin structure provide strategies to design molecules with   enhanced linear and nonlinear response functions.

      Abstract:

      The variation in the ground-state dipole moment, polarizability   and the 1st hyperpolarizability for non-chelated   porphyrins are studied with increase in the inter-dipolar angles   between the pyrrole rings. The different dipolar orientations are   realized through twisting of one of the ring along the porphyrin   plane. Computations performed on both conformational and   configurational isomers of porphyins lead to a variety of   structures. For the conformational distortions, the dipole-moment   (μ), the polarizability (α) and the 1st  hyperpolarizabilities (β) increase with increase in the   distortions. This is understood on the basis of a simple   excitonic picture wherein the splitting due to dipolar   interactions reduces with increase in the distortions which   effectively reduces the optical gap for the system. The   computations reveal that dihedral twists within the conventional   porphyrin structure provide strategies to design molecules with   enhanced linear and nonlinear response functions.

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