Abstract

ConspectusThe electron’s spin, its intrinsic angular momentum, is a quantum property that plays a critical role in determining the electronic structure of molecules. Despite its importance, it is not used often for controlling chemical processes, photochemistry excluded. The reason is that many organic molecules have a total spin zero, namely, all the electrons are paired. Even for molecules with high spin multiplicity, the spin orientation is usually only weakly coupled to the molecular frame of nuclei and hence to the molecular orientation. Therefore, controlling the spin orientation usually does not provide a handle on controlling the geometry of the molecular species during a reaction. About two decades ago, however, a new phenomenon was discovered that relates the electron’s spin to the handedness of chiral molecules and is now known as the chiral induced spin selectivity (CISS) effect. It was established that the efficiency of electron transport through chiral molecules depends on the electron spin and that it changes with the enantiomeric form of a molecule and the direction of the electron’s linear momentum. This property means that, for chiral molecules, the electron spin is strongly coupled to the molecular frame. Over the past few years, we and others have shown that this feature can be used to provide spin-control over chemical reactions and to perform enantioseparations with magnetic surfaces.In this Account, we describe the CISS effect and demonstrate spin polarization effects on chemical reactions. Explicitly, we describe a number of processes that can be controlled by the electron’s spin, among them the interaction of chiral molecules with ferromagnetic surfaces, the multielectron oxidation of water, and enantiospecific electrochemistry. Interestingly, it has been shown that the effect also takes place in inorganic chiral oxides like copper oxide, aluminum oxide, and cobalt oxide. The CISS effect results from the coupling between the electron linear momentum and its spin in a chiral system. Understanding the implications of this interaction promises to reveal a previously unappreciated role for chirality in biology, where chiral molecules are ubiquitous, and opens a new avenue into spin-controlled processes in chemistry.

Highlights

  • Electron spin is essential for understanding chemical bonding, but the use of spin-control in synthetic chemistry is not widespread.[5]

  • The field of “Spin Chemistry” is growing,[6] spin effects are usually associated with radical pair reactions

  • Even though radical chemistry represents a general class of chemical reactivity and radical pair reactions display significant magnetic field effects,[7] spin considerations do not typically provide stereospecificity in bimolecular reactions or in reactions between radicals and surfaces

Read more

Summary

Article Recommendations

CONSPECTUS: The electron’s spin, its intrinsic angular momentum, is a quantum property that plays a critical role in determining the electronic structure of molecules. Despite its importance, it is not used often for controlling chemical processes, photochemistry excluded. It was established that the efficiency of electron transport through chiral molecules depends on the electron spin and that it changes with the enantiomeric form of a molecule and the direction of the electron’s linear momentum This property means that, for chiral molecules, the electron spin is strongly coupled to the molecular frame. J. Chiral-selective Chemistry Induced by Spin-polarized Secondary Electrons from a Magnetic Substrate. Mater. 2019, 31, 1904206.4 The f irst direct measurement of spin exchange interactions with chiral molecules is presented here

■ INTRODUCTION
■ ACKNOWLEDGMENTS
■ REFERENCES
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call