Nonlinear Optical Properties and Excited-State Dynamics of Highly Symmetric Expanded Porphyrins
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- 作者：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
- 刊名：Journal of the American Chemical Society
- 出版年：2006
- 出版时间：November 1, 2006
- 年：2006
- 卷：128
- 期：43
- 页码：14128 - 14134
- 全文大小：110K
- 年卷期：v.128,no.43(November 1, 2006)
- ISSN：1520-5126
文摘
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 closelymatched 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 
-electrons. Two of the systems, [28]hexaphyrin and amethyrin, were considered to beantiaromatic as judged from a simple application of Hückel's [4n + 2] rule. These systems displayed positiveNICS(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 -electrons (cyclo[n]pyrrole, n = 6,7, and 8, respectively) were characterized by a linear correlation between the NICS and TPA values. Inthe case of the oligopyrrolic macrocycles containing 26 -electron systems, a further correlation betweenthe molecular structure and various markers associated with aromaticity was seen. In particular, a decreasein the excited state lifetimes and an increase in the TPA values were seen as the flexibility of the systemsincreased. Based on the findings presented here, it is proposed that various readily measurable opticalproperties, including the two-photon absorption cross-section, can provide a quantitative experimentalmeasure of aromaticity in macrocyclic -conjugated systems.
-electrons. Two of the systems, [28]hexaphyrin and amethyrin, were considered to beantiaromatic as judged from a simple application of Hückel's [4n + 2] rule. These systems displayed positiveNICS(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 -electrons (cyclo[n]pyrrole, n = 6,7, and 8, respectively) were characterized by a linear correlation between the NICS and TPA values. Inthe case of the oligopyrrolic macrocycles containing 26 -electron systems, a further correlation betweenthe molecular structure and various markers associated with aromaticity was seen. In particular, a decreasein the excited state lifetimes and an increase in the TPA values were seen as the flexibility of the systemsincreased. Based on the findings presented here, it is proposed that various readily measurable opticalproperties, including the two-photon absorption cross-section, can provide a quantitative experimentalmeasure of aromaticity in macrocyclic -conjugated systems.