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Electronic structure and photophysics of a supermolecular iron complex having a long MLCT-state lifetime and panchromatic absorption.

Publication ,  Journal Article
Jiang, T; Bai, Y; Zhang, P; Han, Q; Mitzi, DB; Therien, MJ
Published in: Proceedings of the National Academy of Sciences of the United States of America
August 2020

Exploiting earth-abundant iron-based metal complexes as high-performance photosensitizers demands long-lived electronically excited metal-to-ligand charge-transfer (MLCT) states, but these species suffer typically from femtosecond timescale charge-transfer (CT)-state quenching by low-lying nonreactive metal-centered (MC) states. Here, we engineer supermolecular Fe(II) chromophores based on the bis(tridentate-ligand)metal(II)-ethyne-(porphinato)zinc(II) conjugated framework, previously shown to give rise to highly delocalized low-lying 3MLCT states for other Group VIII metal (Ru, Os) complexes. Electronic spectral, potentiometric, and ultrafast pump-probe transient dynamical data demonstrate that a combination of a strong σ-donating tridentate ligand and a (porphinato)zinc(II) moiety with low-lying π*-energy levels, sufficiently destabilize MC states and stabilize supermolecular MLCT states to realize Fe(II) complexes that express 3MLCT state photophysics reminiscent of their heavy-metal analogs. The resulting Fe(II) chromophore archetype, FeNHCPZn, features a highly polarized CT state having a profoundly extended 3MLCT lifetime (160 ps), 3MLCT phosphorescence, and ambient environment stability. Density functional and domain-based local pair natural orbital coupled cluster [DLPNO-CCSD(T)] theory reveal triplet-state wavefunction spatial distributions consistent with electronic spectroscopic and excited-state dynamical data, further underscoring the dramatic Fe metal-to-extended ligand CT character of electronically excited FeNHCPZn. This design further prompts intense panchromatic absorptivity via redistributing high-energy absorptive oscillator strength throughout the visible spectral domain, while maintaining a substantial excited-state oxidation potential for wide-ranging photochemistry--highlighted by the ability of FeNHCPZn to photoinject charges into a SnO2/FTO electrode in a dye-sensitized solar cell (DSSC) architecture. Concepts enumerated herein afford opportunities for replacing traditional rare-metal-based emitters for solar-energy conversion and photoluminescence applications.

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Published In

Proceedings of the National Academy of Sciences of the United States of America

DOI

EISSN

1091-6490

ISSN

0027-8424

Publication Date

August 2020

Volume

117

Issue

34

Start / End Page

20430 / 20437
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Jiang, T., Bai, Y., Zhang, P., Han, Q., Mitzi, D. B., & Therien, M. J. (2020). Electronic structure and photophysics of a supermolecular iron complex having a long MLCT-state lifetime and panchromatic absorption. Proceedings of the National Academy of Sciences of the United States of America, 117(34), 20430–20437. https://doi.org/10.1073/pnas.2009996117
Jiang, Ting, Yusong Bai, Peng Zhang, Qiwei Han, David B. Mitzi, and Michael J. Therien. “Electronic structure and photophysics of a supermolecular iron complex having a long MLCT-state lifetime and panchromatic absorption.Proceedings of the National Academy of Sciences of the United States of America 117, no. 34 (August 2020): 20430–37. https://doi.org/10.1073/pnas.2009996117.
Jiang T, Bai Y, Zhang P, Han Q, Mitzi DB, Therien MJ. Electronic structure and photophysics of a supermolecular iron complex having a long MLCT-state lifetime and panchromatic absorption. Proceedings of the National Academy of Sciences of the United States of America. 2020 Aug;117(34):20430–7.
Jiang, Ting, et al. “Electronic structure and photophysics of a supermolecular iron complex having a long MLCT-state lifetime and panchromatic absorption.Proceedings of the National Academy of Sciences of the United States of America, vol. 117, no. 34, Aug. 2020, pp. 20430–37. Epmc, doi:10.1073/pnas.2009996117.
Jiang T, Bai Y, Zhang P, Han Q, Mitzi DB, Therien MJ. Electronic structure and photophysics of a supermolecular iron complex having a long MLCT-state lifetime and panchromatic absorption. Proceedings of the National Academy of Sciences of the United States of America. 2020 Aug;117(34):20430–20437.
Journal cover image

Published In

Proceedings of the National Academy of Sciences of the United States of America

DOI

EISSN

1091-6490

ISSN

0027-8424

Publication Date

August 2020

Volume

117

Issue

34

Start / End Page

20430 / 20437