Conjugated-linker dependence of the photophysical properties and electronic structure of chlorin dyads
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Author/Creator ORCID
Date
2021-04-20
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Citation of Original Publication
Kang, Hyun Suk et al. Conjugated-linker dependence of the photophysical properties and electronic structure of chlorin dyads.Journal of Porphyrins and Phthalocyanines 25, No. 07 (2021): 639-663. https://www.worldscientific.com/doi/10.1142/S1088424621500620
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Electronic version of an article published as Journal of Porphyrins and Phthalocyanines 25, No. 07, 2021, 639-663 https://doi.org/10.1142/S1088424621500620 © [copyright World Scientific Publishing Company] https://www.worldscientific.com/doi/pdf/10.1142/S1088424621500620
Subjects
Abstract
The synthesis, photophysical properties and electronic structure of seven new chlorin dyads and associated benchmark monomers are described. Each dyad contains two identical chlorins linked at the macrocycle β-pyrrole 13-position. The extent of electronic communication between chlorin constituents depends on the nature of the conjugated linker. The communication is assessed by modification of prominent ground-state absorption and redox properties, rate constants and yields of excited-state decay processes, and molecular-orbital characteristics. Relative to the benchmark monomers, the chlorin dyads in toluene exhibit a substantial bathochromic shift of the long-wavelength absorption band (30 nm average), two-fold increased radiative rate constant [average (10 ns)−1vs. (22 ns)−1], reduced singlet excited-state lifetimes (average 5.0 ns vs. 8.2 ns), and increased fluorescence quantum yields (average 0.56 vs. 0.42). The excited-state lifetime and fluorescence yield for the chlorin dyad with a benzothiadiazole linker are reduced substantially in benzonitrile vs. toluene due largely to ∼25-fold accelerated internal conversion. The results aid design strategies for molecular architectures that may find utility in solar-energy conversion and photomedicine.