TY - JOUR
T1 - Plasmon-Driven C-N Bond Cleavage across a Series of Viologen Derivatives
AU - Brooks, James L.
AU - Chulhai, Dhabih V.
AU - Yu, Ziwei
AU - Goodpaster, Jason D.
AU - Frontiera, Renee R.
N1 - Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2019/12/5
Y1 - 2019/12/5
N2 - The optical excitation of surface plasmons leads to the generation of highly enhanced nanoscale local fields and an abundance of harvestable hot carriers. When certain analytes are positioned within these unique environments, surface plasmons may be able to induce chemical reactions that are energetically unfavorable under standard conditions. Sometimes, the plasmonic environments can initiate entirely new reaction pathways for the chemical adsorbates. Here, we investigate the nature of plasmon-driven reactions on three viologen derivatives: methyl viologen, ethyl viologen, and benzyl viologen. Viologens have traditionally been employed as excellent redox agents due to their ability to reversibly stabilize additional electrons in their molecular structures. However, by using surface-enhanced Raman spectroscopy, we were able to directly observe a C-N bond cleavage on benzyl and ethyl viologen to form 4,4′-bipyridine on the surface of gold film-over-nanosphere substrates. Surprisingly, methyl viologen does not undergo a similar process. We posit that this differing reactivity may be due to changes in adsorption geometry or in reduction potential. Using both spectroscopic and theoretical methods, we were able to confirm 4,4′-bipyridine as the plasmon-mediated photoproduct. This work highlights the novelty of using plasmonic environments to access new chemical reactions and adds to the expanding library of plasmon-mediated chemical reactions.
AB - The optical excitation of surface plasmons leads to the generation of highly enhanced nanoscale local fields and an abundance of harvestable hot carriers. When certain analytes are positioned within these unique environments, surface plasmons may be able to induce chemical reactions that are energetically unfavorable under standard conditions. Sometimes, the plasmonic environments can initiate entirely new reaction pathways for the chemical adsorbates. Here, we investigate the nature of plasmon-driven reactions on three viologen derivatives: methyl viologen, ethyl viologen, and benzyl viologen. Viologens have traditionally been employed as excellent redox agents due to their ability to reversibly stabilize additional electrons in their molecular structures. However, by using surface-enhanced Raman spectroscopy, we were able to directly observe a C-N bond cleavage on benzyl and ethyl viologen to form 4,4′-bipyridine on the surface of gold film-over-nanosphere substrates. Surprisingly, methyl viologen does not undergo a similar process. We posit that this differing reactivity may be due to changes in adsorption geometry or in reduction potential. Using both spectroscopic and theoretical methods, we were able to confirm 4,4′-bipyridine as the plasmon-mediated photoproduct. This work highlights the novelty of using plasmonic environments to access new chemical reactions and adds to the expanding library of plasmon-mediated chemical reactions.
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U2 - 10.1021/acs.jpcc.9b08179
DO - 10.1021/acs.jpcc.9b08179
M3 - Article
AN - SCOPUS:85075660524
SN - 1932-7447
VL - 123
SP - 29306
EP - 29313
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 48
ER -