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Title: Extraordinary Redox Activities in Ladder-Type Conjugated Molecules Enabled by B ← N Coordination-Promoted Delocalization and Hyperconjugation

Abstract

The introduction of B ← N coordinate bond-isoelectronic to C-C single bond-into π-systems represents a promising strategy to impart exotic redox and electrochromic properties into conjugated organic molecules and macromolecules. To achieve both reductive and oxidative activities using this strategy, a cruciform ladder-type molecular constitution was designed to accommodate oxidation-active, reduction-active, and B ← N coordination units into a compact structure. Two such compounds (BN-F and BN-Ph) were synthesized via highly efficient N-directed borylation. These molecules demonstrated well-separated, two reductive and two oxidative electron-transfer processes, corresponding to five distinct yet stable oxidation states, including a rarely observed boron-containing radical cation. Spectroelectrochemical measurements revealed unique optical characteristics for each of these reduced/oxidized species, demonstrating multicolor electrochromism with excellent recyclability. Distinct color changes were observed between each redox state with clear isosbestic points on the absorption spectra. Here, the underlying redox mechanism was elucidated by a combination of computational and experimental investigations. Single-crystal X-ray diffraction analysis on the neutral state, the oxidized radical cation, and the reduced dianion of BN-Ph revealed structural transformations into two distinct quinonoid constitutions during the oxidation and reduction processes, respectively. B ← N coordination played an important role in rendering the robust and reversible multistage redox properties, by extendingmore » the charge and spin delocalization, by modulating the π-electron density, and by a newly established hyperconjugation mechanism.« less

Authors:
ORCiD logo [1];  [1];  [1];  [2];  [1];  [1];  [2]; ORCiD logo [2]; ORCiD logo [1]
  1. Texas A & M Univ., College Station, TX (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1563988
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 140; Journal Issue: 51; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Zhu, Congzhi, Ji, Xiaozhou, You, Di, Chen, Teresa L., Mu, Anthony U., Barker, Kayla P., Klivansky, Liana M., Liu, Yi, and Fang, Lei. Extraordinary Redox Activities in Ladder-Type Conjugated Molecules Enabled by B ← N Coordination-Promoted Delocalization and Hyperconjugation. United States: N. p., 2018. Web. doi:10.1021/jacs.8b11337.
Zhu, Congzhi, Ji, Xiaozhou, You, Di, Chen, Teresa L., Mu, Anthony U., Barker, Kayla P., Klivansky, Liana M., Liu, Yi, & Fang, Lei. Extraordinary Redox Activities in Ladder-Type Conjugated Molecules Enabled by B ← N Coordination-Promoted Delocalization and Hyperconjugation. United States. doi:10.1021/jacs.8b11337.
Zhu, Congzhi, Ji, Xiaozhou, You, Di, Chen, Teresa L., Mu, Anthony U., Barker, Kayla P., Klivansky, Liana M., Liu, Yi, and Fang, Lei. Mon . "Extraordinary Redox Activities in Ladder-Type Conjugated Molecules Enabled by B ← N Coordination-Promoted Delocalization and Hyperconjugation". United States. doi:10.1021/jacs.8b11337. https://www.osti.gov/servlets/purl/1563988.
@article{osti_1563988,
title = {Extraordinary Redox Activities in Ladder-Type Conjugated Molecules Enabled by B ← N Coordination-Promoted Delocalization and Hyperconjugation},
author = {Zhu, Congzhi and Ji, Xiaozhou and You, Di and Chen, Teresa L. and Mu, Anthony U. and Barker, Kayla P. and Klivansky, Liana M. and Liu, Yi and Fang, Lei},
abstractNote = {The introduction of B ← N coordinate bond-isoelectronic to C-C single bond-into π-systems represents a promising strategy to impart exotic redox and electrochromic properties into conjugated organic molecules and macromolecules. To achieve both reductive and oxidative activities using this strategy, a cruciform ladder-type molecular constitution was designed to accommodate oxidation-active, reduction-active, and B ← N coordination units into a compact structure. Two such compounds (BN-F and BN-Ph) were synthesized via highly efficient N-directed borylation. These molecules demonstrated well-separated, two reductive and two oxidative electron-transfer processes, corresponding to five distinct yet stable oxidation states, including a rarely observed boron-containing radical cation. Spectroelectrochemical measurements revealed unique optical characteristics for each of these reduced/oxidized species, demonstrating multicolor electrochromism with excellent recyclability. Distinct color changes were observed between each redox state with clear isosbestic points on the absorption spectra. Here, the underlying redox mechanism was elucidated by a combination of computational and experimental investigations. Single-crystal X-ray diffraction analysis on the neutral state, the oxidized radical cation, and the reduced dianion of BN-Ph revealed structural transformations into two distinct quinonoid constitutions during the oxidation and reduction processes, respectively. B ← N coordination played an important role in rendering the robust and reversible multistage redox properties, by extending the charge and spin delocalization, by modulating the π-electron density, and by a newly established hyperconjugation mechanism.},
doi = {10.1021/jacs.8b11337},
journal = {Journal of the American Chemical Society},
number = 51,
volume = 140,
place = {United States},
year = {2018},
month = {12}
}

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Works referencing / citing this record:

CCDC 1874349: Experimental Crystal Structure Determination
dataset, January 2018


CCDC 1886175: Experimental Crystal Structure Determination
dataset, January 2018


CCDC 1886176: Experimental Crystal Structure Determination
dataset, January 2018


B–N coordinated triaryl pyrazole: effect of dimerization, and optical and NLO properties
journal, January 2019

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