Distinct Photophysical and Electronic Characteristics of Strongly Coupled Dyads Containing a Perylene Accessory Pigment and a Porphyrin, Chlorin, or Bacteriochlorin

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• 作者：Jieqi Wang ; Eunkyung Yang ; James R. Diers ; Dariusz M. Niedzwiedzki ; Christine Kirmaier ; David F. Bocian ; Jonathan S. Lindsey ; Dewey Holten
• 刊名：The Journal of Physical Chemistry B
• 出版年：2013
• 出版时间：August 8, 2013
• 年：2013
• 卷：117
• 期：31
• 页码：9288-9304
• 全文大小：783K
• 年卷期：v.117,no.31(August 8, 2013)
• ISSN：1520-5207

文摘

The synthesis, photophysical, redox, and molecular-orbital characteristics of three perylene鈥搕etrapyrrole dyads were investigated to elucidate characteristics favorable for use in next-generation light-harvesting assemblies. Each dyad contains a common perylene-monoimide that is linked at the 9-position via an ethynyl group to the meso-position of the tetrapyrrole. The tetrapyrroles include a porphyrin, chlorin, and bacteriochlorin, which have zero, one, and two reduced pyrrole rings, respectively. The increased pyrrole-ring reduction results in a progressive red shift and intensification of the lowest-energy absorption band, as exemplified by benchmark monomers. The direct ethyne linkage and accompanying strong perylene鈥搕etrapyrrole electronic coupling in the dyads is evident by significant differences in optical absorption versus the sum of the features of the constituents. The perturbations decrease for the tetrapyrrole constituent along the series porphyrin > chlorin > bacteriochlorin. This trend is explained by the relative configurational mixing in the tetrapyrrole excited states and how the configuration-interaction energy (and not simply the energies of the configurations) is affected by coupling to the perylene. The perylene鈥搕etrapyrrole electronic coupling is further evidenced in the redox and MO characteristics of the three dyads. All three dyads in nonpolar solvents exhibit relatively long singlet excited-state lifetimes (3.3鈥?.5 ns) and relatively large fluorescence quantum yields (0.14鈥?.40). Collectively, the physicochemical characteristics of the strongly coupled perylene鈥搕etrapyrrole dyads render these architectures excellent candidates for light-harvesting materials with significant, even panchromatic, near-ultraviolet to near-infrared absorption.