title: Manipulating Magneto-Optic Properties of a Chiral Polymer by Doping with Stable Organic Biradicals.
abstract: We report the first example of tuning the large magneto-optic activity of a chiral polymer by addition of stable organic biradicals. The spectral dispersion of Verdet constant, which quantifies magneto-optic response, differs substantially between the base polymer and the nanocomposite. We employed a microscopic model, supported by atomistic calculations, to rationalize the behavior of this nanocomposite system. The suggested mechanism involves magnetic coupling between helical conjugated polymer fibrils, with spatially delocalized helical π-electron density, and the high density of spin states provided by the biradical dopants, which leads to synergistic enhancement of magneto-optic response. Our combined experimental and theoretical studies reveal that the manipulation of magnetic coupling in this new class of magneto-optic materials offers an opportunity to tailor the magnitude, sign, and spectral dispersion of the Verdet constant over a broad range of wavelengths, from the UV to the near-IR. This provides a new strategy for creating conformable materials with extraordinary magneto-optic activity, which can ultimately enable new applications requiring spatially and temporally resolved measurement of extremely weak magnetic fields. In particular, magneto-optic materials, presently employed in technologies like optical isolators and optical circulators, could be used in ultrasensitive optical magnetometers. This, in turn, could open a path toward mapping of brain activity via optical magnetoencephalography.
authors: The Institute for Lasers, Photonics and Biophotonics, State University of New York at Buffalo , Buffalo, New York 14260, United States.
authors: Chang-Keun
authors: CK
authors: Lim
authors: The Institute for Lasers, Photonics and Biophotonics, State University of New York at Buffalo , Buffalo, New York 14260, United States.
authors: Min Ju
authors: MJ
authors: Cho
authors: The Institute for Lasers, Photonics and Biophotonics, State University of New York at Buffalo , Buffalo, New York 14260, United States.
authors: Ajay
authors: A
authors: Singh
authors: Department of Chemical and Biological Engineering, State University of New York at Buffalo , Buffalo, New York 14260, United States.
authors: Qi
authors: Q
authors: Li
authors: The Institute for Lasers, Photonics and Biophotonics, State University of New York at Buffalo , Buffalo, New York 14260, United States.
authors: Won Jin
authors: WJ
authors: Kim
authors: The Institute for Lasers, Photonics and Biophotonics, State University of New York at Buffalo , Buffalo, New York 14260, United States.
authors: Hong Sub
authors: HS
authors: Jee
authors: Department of Chemistry, University of Rochester , Rochester, New York 14627, United States.
authors: Kathlyn L
authors: KL
authors: Fillman
authors: Department of Chemistry, University of Rochester , Rochester, New York 14627, United States.
authors: Stephanie H
authors: SH
authors: Carpenter
authors: Department of Chemistry, University of Rochester , Rochester, New York 14627, United States.
authors: Michael L
authors: ML
authors: Neidig
authors: The Institute for Lasers, Photonics and Biophotonics, State University of New York at Buffalo , Buffalo, New York 14260, United States.
authors: Alexander
authors: A
authors: Baev
authors: The Institute for Lasers, Photonics and Biophotonics, State University of New York at Buffalo , Buffalo, New York 14260, United States.|Department of Chemical and Biological Engineering, State University of New York at Buffalo , Buffalo, New York 14260, United States.
authors: Mark T
authors: MT
authors: Swihart
authors: The Institute for Lasers, Photonics and Biophotonics, State University of New York at Buffalo , Buffalo, New York 14260, United States.
authors: Paras N
authors: PN
authors: Prasad
keywords: Faraday rotation; biradicals; chirality; polymers