DUGi

Evaluation of the nonlinear optical properties for an expanded porphyrin Hückel-Möbius aromaticity switch

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The conformational flexibility of the expanded porphyrins allows them to achieve different topologies with distinct aromaticities and nonlinear optical properties (NLOP). For instance, it is possible to switch between Möbius and Hückel topologies applying only small changes in the external conditions or in the structure of the ring. In this work, we evaluate the electronic and vibrational contributions to static and dynamic NLOP of the Hückel and Möbius conformers of A,D-di-pbenzi[28] hexaphyrin (1.1.1.1.1.1) synthesized by Latos-Gra˙zy´nski and co-workers [Angew. Chem., Int. Ed. 46, 7869 (2007)]. Calculations are performed at the HF, M052X, and CAM-B3LYP levels using the 6-31G, 6-311G(d), and 6-31+G(d) basis sets. Our results conclude that M052X/6-31G and CAM-B3LYP/6-31G methods provide a correct qualitative description of the electronic and vibrational contributions for the NLOP of expanded porphyrins. The studied systems show high NLOP with large differences between the Möbius and Hückel conformations (around 1 × 106 a.u. for γ¯ ). The obtained results indicate that the expanded porphyrins are promising systems to manufacture Hückel-to-Möbius topological switches

This research has been supported by the Spanish Direccion General de Investigacion Cientifica y Tecnica (DGYCIT, Grant Nos. CTQ2011-27812/BQU and CTQ2011-23156/BQU), the Generalitat de Catalunya (Grant Nos. 2009SGR01472 and 2009SGR637), and the Research Executive Agency (Grant Agreement No. PERG05-GA-2009-249310). The calculations described in this work were carried out at the Centre de Supercomputacio de Catalunya (CESCA). M. T-S. acknowledges the CSIC for the JAE-DOC contract

American Institute of Physics