Electronic Structure and Excited-State Dynamics of Rylene–Tetrapyrrole Panchromatic Absorbers
- North Carolina State Univ., Raleigh, NC (United States)
- Washington Univ., St. Louis, MO (United States)
- Univ. of California, Riverside, CA (United States)
Panchromatic absorbers have potential applications in molecular-based energy-conversion schemes. A prior porphyrin–perylene dyad (P-PMI, where “MI” denotes monoimide) coupled via an ethyne linker exhibits panchromatic absorption (350–700 nm) and a tetrapyrrole-like lowest singlet excited state with a relatively long singlet excited-state lifetime (τS) and increased fluorescence quantum yield (Φf) versus the parent porphyrin. To explore the extension of panchromaticity to longer wavelengths, three arrays have been synthesized: a chlorin–terrylene dyad (C-TMI), a bacteriochlorin–terrylene dyad (B-TMI), and a perylene–porphyrin–terrylene triad (PMI-P-TMI), where the terrylene, a π-extended homologue of perylene, is attached via an ethyne linker. Characterization of the spectra (absorption and fluorescence), excited-state properties (lifetime, yields, and rate constants of decay pathways), and molecular-orbital characteristics reveals unexpected subtleties. The wavelength of the red-region absorption band increases in the order C-TMI (705 nm) < PMI-P-TMI (749 nm) < B-TMI (774 nm), yet each array exhibits diminished Φf and shortened τS values. The PMI-P-TMI triad in toluene exhibits Φf = 0.038 and τS = 139 ps versus the all-perylene triad (PMI-P-PMI) for which Φf = 0.26 and τS = 2000 ps. The results highlight design constraints for auxiliary pigments with tetrapyrroles to achieve panchromatic absorption with retention of viable excited-state properties.
- Research Organization:
- Washington Univ., St. Louis, MO (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- FG02-05ER15661; SC0001035
- OSTI ID:
- 1830802
- Journal Information:
- Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory, Vol. 125, Issue 36; ISSN 1089-5639
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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