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Title: Tunable Rh 2(II,II) Light Absorbers as Excited State Electron Donors and Acceptors Accessible with Red/Near-IR Irradiation

Abstract

In this study, a series of dirhodium(II,II) paddlewheeel complexes of the type cis-[Rh 2(μ-DTolF) 2(μ-L) 2][BF 4] 2, where DTolF = N,N'-di(p-tolyl)formamidinate and L = 1,8-naphthyridine (np), 2-(pyridin-2-yl)-1,8-naphthyridine (pynp), 2-(quinolin-2-yl)-1,8-naphthyridine (qnnp), and 2-(1,8-naphthyridin-2-yl)quinoxaline (qxnp), were synthesized and characterized. These molecules feature new tridentate ligands that concomitantly bridge the dirhodium core and cap the axial positions. The complexes absorb light strongly throughout the ultraviolet/visible range and into the near-infrared region and exhibit relatively long-lived triplet excited-state lifetimes. Both the singlet and triplet excited states exhibit metal/ligand-to-ligand charge transfer (ML-LCT) in nature as determined by transient absorption spectroscopy and spectroelectrochemistry measurements. When irradiated with low-energy light, these black dyes are capable of undergoing reversible bimolecular electron transfer both to the electron acceptor methyl viologen and from the electron donor p-phenylenediamine. Photoinduced charge transfer in the latter was inaccessible with previous Rh 2(II,II) complexes. Finally, these results underscore the fact that the excited state of this class of molecules can be readily tuned for electron-transfer reactions upon simple synthetic modification and highlight their potential as excellent candidates for p- and n-type semiconductor applications and for improved harvesting of low-energy light to drive useful photochemical reactions.

Authors:
ORCiD logo [1]; ORCiD logo [2];  [1];  [1]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [3]
  1. The Ohio State Univ., Columbus, OH (United States). Department of Chemistry and Biochemistry
  2. Texas A & M Univ., College Station, TX (United States). Department of Chemistry
  3. The Ohio State Univ., Columbus, OH (United States). Department of Chemistry and Biochemistry
Publication Date:
Research Org.:
The Ohio State Univ., Columbus, OH (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1430408
Grant/Contract Number:
SC0010542; SC0010721; AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Name: Journal of the American Chemical Society; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Whittemore, Tyler, Millet, Agustin, Sayre, Hannah, Xue, Congcong, Dolinar, Brian, White, Eryn, Dunbar, Kim, and Turro, Claudia. Tunable Rh2(II,II) Light Absorbers as Excited State Electron Donors and Acceptors Accessible with Red/Near-IR Irradiation. United States: N. p., 2018. Web. doi:10.1021/jacs.8b00599.
Whittemore, Tyler, Millet, Agustin, Sayre, Hannah, Xue, Congcong, Dolinar, Brian, White, Eryn, Dunbar, Kim, & Turro, Claudia. Tunable Rh2(II,II) Light Absorbers as Excited State Electron Donors and Acceptors Accessible with Red/Near-IR Irradiation. United States. doi:10.1021/jacs.8b00599.
Whittemore, Tyler, Millet, Agustin, Sayre, Hannah, Xue, Congcong, Dolinar, Brian, White, Eryn, Dunbar, Kim, and Turro, Claudia. Wed . "Tunable Rh2(II,II) Light Absorbers as Excited State Electron Donors and Acceptors Accessible with Red/Near-IR Irradiation". United States. doi:10.1021/jacs.8b00599.
@article{osti_1430408,
title = {Tunable Rh2(II,II) Light Absorbers as Excited State Electron Donors and Acceptors Accessible with Red/Near-IR Irradiation},
author = {Whittemore, Tyler and Millet, Agustin and Sayre, Hannah and Xue, Congcong and Dolinar, Brian and White, Eryn and Dunbar, Kim and Turro, Claudia},
abstractNote = {In this study, a series of dirhodium(II,II) paddlewheeel complexes of the type cis-[Rh2(μ-DTolF)2(μ-L)2][BF4]2, where DTolF = N,N'-di(p-tolyl)formamidinate and L = 1,8-naphthyridine (np), 2-(pyridin-2-yl)-1,8-naphthyridine (pynp), 2-(quinolin-2-yl)-1,8-naphthyridine (qnnp), and 2-(1,8-naphthyridin-2-yl)quinoxaline (qxnp), were synthesized and characterized. These molecules feature new tridentate ligands that concomitantly bridge the dirhodium core and cap the axial positions. The complexes absorb light strongly throughout the ultraviolet/visible range and into the near-infrared region and exhibit relatively long-lived triplet excited-state lifetimes. Both the singlet and triplet excited states exhibit metal/ligand-to-ligand charge transfer (ML-LCT) in nature as determined by transient absorption spectroscopy and spectroelectrochemistry measurements. When irradiated with low-energy light, these black dyes are capable of undergoing reversible bimolecular electron transfer both to the electron acceptor methyl viologen and from the electron donor p-phenylenediamine. Photoinduced charge transfer in the latter was inaccessible with previous Rh2(II,II) complexes. Finally, these results underscore the fact that the excited state of this class of molecules can be readily tuned for electron-transfer reactions upon simple synthetic modification and highlight their potential as excellent candidates for p- and n-type semiconductor applications and for improved harvesting of low-energy light to drive useful photochemical reactions.},
doi = {10.1021/jacs.8b00599},
journal = {Journal of the American Chemical Society},
number = ,
volume = ,
place = {United States},
year = {Wed Apr 04 00:00:00 EDT 2018},
month = {Wed Apr 04 00:00:00 EDT 2018}
}

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