Nonlinear optical properties and excited-state dynamics of highly symmetric expanded porphyrins

Zin Seok Yoon, Jung Ho Kwon, Min Chul Yoon, Mi Kyoung Koh, Su Bum Noh, Jonathan L. Sessler, Jeong Tae Lee, Daniel Seidel, Apolonio Aguilar, Soji Shimizu, Masaaki Suzuki, Atsuhiro Osuka, Dongho Kim

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Abstract

A strong correlation among calculated Nucleus-Independent Chemical Shift (NICS) values, molecular planarity, and the observed two-photon absorption (TPA) values was found for a series of closely matched expanded porphyrins. The expanded porphyrins in question consisted of [26]hexaphyrin, [28]-hexaphyrin, rubyrin, amethyrin, cyclo[6]pyrrole, cyclo[7]pyrrole, and cyclo[8]pyrrole containing 22, 24, 26, 28, and 30 π-electrons. Two of the systems, [28]hexaphyrin and amethyrin, were considered to be antiaromatic as judged from a simple application of Hückel's [4n + 2] rule. These systems displayed positive NICS(0) values (+43.5 and +17.1 ppm, respectively) and gave rise to TPA values of 2600 and 3100 GM, respectively. By contrast, a set of congeners containing 22, 26, and 30 π-electrons (cyclo[n]pyrrole, n = 6, 7, and 8, respectively) were characterized by a linear correlation between the NICS and TPA values. In the case of the oligopyrrolic macrocycles containing 26 π-electron systems, a further correlation between the molecular structure and various markers associated with aromaticity was seen. In particular, a decrease in the excited state lifetimes and an increase in the TPA values were seen as the flexibility of the systems increased. Based on the findings presented here, it is proposed that various readily measurable optical properties, including the two-photon absorption cross-section, can provide a quantitative experimental measure of aromaticity in macrocyclic π-conjugated systems.

Original languageEnglish
Pages (from-to)14128-14134
Number of pages7
JournalJournal of the American Chemical Society
Volume128
Issue number43
DOIs
Publication statusPublished - 2006 Nov 1

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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    Yoon, Z. S., Kwon, J. H., Yoon, M. C., Koh, M. K., Noh, S. B., Sessler, J. L., Lee, J. T., Seidel, D., Aguilar, A., Shimizu, S., Suzuki, M., Osuka, A., & Kim, D. (2006). Nonlinear optical properties and excited-state dynamics of highly symmetric expanded porphyrins. Journal of the American Chemical Society, 128(43), 14128-14134. https://doi.org/10.1021/ja064773k