Symmetry-Breaking Charge Transfer of Visible Light Absorbing Systems: Zinc Dipyrrins
Abstract
Zinc dipyrrin complexes with two identical dipyrrin ligands absorb strongly at 450–550 nm and exhibit high fluorescence quantum yields in nonpolar solvents (e.g., 0.16–0.66 in cyclohexane) and weak to nonexistent emission in polar solvents (i.e., <10^(–3), in acetonitrile). The low quantum efficiencies in polar solvents are attributed to the formation of a nonemissive symmetry-breaking charge transfer (SBCT) state, which is not formed in nonpolar solvents. Analysis using ultrafast spectroscopy shows that in polar solvents the singlet excited state relaxes to the SBCT state in 1.0–5.5 ps and then decays via recombination to the triplet or ground states in 0.9–3.3 ns. In the weakly polar solvent toluene, the equilibrium between a localized excited state and the charge transfer state is established in 11–22 ps.
Additional Information
© 2014 American Chemical Society. ACS AuthorChoice - This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes. Received: July 9, 2014; Revised: August 27, 2014; Published: August 27, 2014. We thank Dr. Ralf Haiges for the help with crystallographic studies and Dr. Sean Roberts for helpful discussion regarding the TA data. We acknowledge financial support from following organizations: the synthesis and characterization of zinc dipyrrins were supported by the Nanoflex Power Corp.; Xray crystallography was performed on a Bruker APEX II CCD system, acquired with funds provided by the NSF CRIF program (Award 1048807); some of the NMR spectra were recorded on a Varian 400-MR spectrometer, acquired with funds provided by the NSF CRIF program (Award 0840366); ns-to-ms TA experiments were performed at the Beckman Institute Laser Resource Center at Caltech; M.E.E. was supported by NIH Grant RO1-DK019038; ultrafast (fs-to-ns) TA studies were supported by the Center for Energy Nanoscience (CEN) at USC. CEN is an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences (DESC0001013).Attached Files
Published - jp506855t.pdf
Supplemental Material - jp506855t_si_001.pdf
Supplemental Material - jp506855t_si_002.cif
Files
Additional details
- PMCID
- PMC4174994
- Eprint ID
- 51051
- Resolver ID
- CaltechAUTHORS:20141030-092012977
- Nanoflex Power Corp
- CHE-1048807
- NSF
- CHE-0840366
- NSF
- Caltech Beckman Institute
- RO1-DK019038
- NIH
- USC Center for Energy Nanoscience (CEN)
- DE-SC0001013
- Department of Energy (DOE)
- Created
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2014-10-30Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field