3 research outputs found
Can Plasmon Change Reaction Path? : Decomposition of Unsymmetrical Iodonium Salts as an Organic Probe
Plasmon-assisted transformations of organic compounds represent a novel opportunity for conversion of light to chemical energy at room temperature. However, the mechanistic insights of interaction between plasmon energy and organic molecules is still under debate. Herein, we proposed a comprehensive study of the plasmon-assisted reaction mechanism using unsymmetric iodonium salts (ISs) as an organic probe. The experimental and theoretical analysis allow us to exclude the possible thermal effect or hot electron transfer. We found that plasmon interaction with unsymmetrical ISs led to the intramolecular excitation of electron followed by the regioselective cleavage of C–I bond with the formation of electron-rich radical species, which cannot be explained by the hot electron excitation or thermal effects. The high regioselectivity is explained by the direct excitation of electron to LUMO with the formation of a dissociative excited state according to quantum-chemical modeling, which provides novel opportunities for the fine control of reactivity using plasmon energy.Peer reviewe
Chiral Metafilms and Surface Enhanced Raman Scattering For Enantiomeric Discrimination of Helicoid Nanoparticles
Chiral nanophotonic platforms provide a means of creating near fields with
both enhanced asymmetric properties and intensities. They can be exploited for
optical measurements that allow enantiomeric discrimination at detection levels
greater than 6 orders of magnitude than is achieved with conventional chirally
sensitive spectroscopic methods based on circularly polarized light. The
optimal approach for exploiting nanophotonic platforms for chiral detection
would be to use spectroscopic methods that provide a local probe of changes in
the near field environment induced by the presence of chiral species. Here we
show that surface enhanced Raman spectroscopy (SERS) is such a local probe of
the near field environment. We have used it to achieve enantiomeric
discrimination of chiral helicoid nanoparticles deposited on left and
right-handed enantiomorphs of a chiral metafilm. Hotter electromagnetic
hotspots are created for matched combinations of helicoid and metafilms
(left-left and right-right), while mismatched combinations leads to
significantly cooler electromagnetic hotspots. This large enantiomeric
dependency on hotspot intensity is readily detected using SERS with the aid of
an achiral Raman reporter molecule. In effect we have used SERS to distinguish
between the different EM environments of the plasmonic diastereomers produced
by mixing chiral nanoparticles and metafilms. The work demonstrates that by
combining chiral nanophotonic platforms with established SERS strategies new
avenues in ultrasensitive chiral detection can be opened
Сan Plasmon Change Reaction Path? An Unprecedented Regioselective Decomposition of Unsymmetrical Iodonium Salts
Plasmon-assisted transformations of organic compounds
represent a novel opportunity for conversion of light to chemical energy at
room temperature. Herein, we propose a comprehensive investigation of
plasmon-triggered decomposition of iodonium salts containing various
substituents (ISs). We found that plasmon interaction with unsymmetrical ISs
led to the intramolecular excitation of electron followed by the regioselective
cleavage of C–I bond with the formation of electron-rich radical species. Such
unprecedented C–I cleavage brings the possibility of selective surface
modification using ISs. The high regioselectivity is explained by the direct excitation
of electron to LUMO with the formation of dissociative excited state ac-cording
to quantum-chemical modeling.</p