Molecular metals with widely tunable band filling. Response of the collective properties of a phthalocyanine molecular metal to drastic excursions in partial oxidation state and charge-compensating counterions

Manuel Almeida, John G. Gaudiello, Glen E. Kellogg, Stephen M. Tetrick, Tobin J Marks, William J. McCarthy, John C. Butler, Carl R. Kannewurf, Tobin J. Marks

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Abstract

The electrical, optical, and magnetic properties of the partially oxidized, cofacially joined phthalocyanine polymers {[Si(Pc)O]Xy}n are investigated for X- = BF4 -, y = 0.00-0.50; X- = p-toluenesulfonate (TOS-), y = 0.00-0.67; and X- = SO4 2-, y = 0.040, 0.095. As a function of increasing y, the physical properties of the BF4 - and TOS- salts evidence a transition at y ≈ 0.20 from a localized carrier semiconductor or insulator to a molecular metal. Thus, the dc electrical conductivity increases from low values having a temperature dependence most characteristic of disorder and/or hopping transport between localized states to values characteristic of a molecular metal with fluctuation-induced carrier tunneling between relatively large metallike particles. Beyond y ≳ 0.25, the conductivity is only weakly dependent on y. At y ≈ 0.20, the thermoelectric power [S(T)] also changes from behavior characteristic of a p-type semiconductor or insulator to that of a p-type molecular metal. Differences in S(T) between X- = BF4 - and TOS- polymers appear to be due largely to minor structural variations. Optical reflectivity measurements reveal the appearance of a metallike plasma edge at y ≈ 0.20, followed by an incremental shift of this feature to higher energy with further increase in y. The static magnetic susceptibility of {[Si(Pc)O](BF4)y}n evidences an abrupt transition at y ≈ 0.20 from a large concentration of localized, Curie-like spins to Pauli-like behavior characteristic of a molecular metal. Beyond y ≳ 0.30, the Pauli-like susceptibility is nearly independent of y. ESR studies indicate a ligand-centered π-radical-cation electronic structure. For X- = BF4- and TOS-, line-width studies as a function of y evidence a progression from relatively localized to delocalized carriers. It is suggested that the insulator/semiconductor to molecular metal transition in these materials is an Anderson-like transition that arises when the Fermi level crosses a mobility edge from localized states (presumably due to disorder and/or defects) at the tail of the conduction band to delocalized, metallike states. With the possible exception of ESR line-width data, the electrical, optical, and magnetic studies of {[Si(Pc)O] (SO4)0.095}n provide no evidence for an enhanced, carrier-localizing perturbation of the [Si(Pcρ+)O]n band structure by the dinegative off-axis counterions.

Original languageEnglish
Pages (from-to)5271-5284
Number of pages14
JournalJournal of the American Chemical Society
Volume111
Issue number14
Publication statusPublished - 1989

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Metals
Semiconductors
Oxidation
Semiconductor materials
Linewidth
Paramagnetic resonance
Polymers
Thermoelectric power
Electron transitions
Fermi level
Conduction bands
Magnetic susceptibility
Electric Conductivity
Band structure
Electronic structure
Transition metals
Cations
Magnetic properties
Electric properties
Optical properties

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Molecular metals with widely tunable band filling. Response of the collective properties of a phthalocyanine molecular metal to drastic excursions in partial oxidation state and charge-compensating counterions. / Almeida, Manuel; Gaudiello, John G.; Kellogg, Glen E.; Tetrick, Stephen M.; Marks, Tobin J; McCarthy, William J.; Butler, John C.; Kannewurf, Carl R.; Marks, Tobin J.

In: Journal of the American Chemical Society, Vol. 111, No. 14, 1989, p. 5271-5284.

Research output: Contribution to journalArticle

Almeida, Manuel ; Gaudiello, John G. ; Kellogg, Glen E. ; Tetrick, Stephen M. ; Marks, Tobin J ; McCarthy, William J. ; Butler, John C. ; Kannewurf, Carl R. ; Marks, Tobin J. / Molecular metals with widely tunable band filling. Response of the collective properties of a phthalocyanine molecular metal to drastic excursions in partial oxidation state and charge-compensating counterions. In: Journal of the American Chemical Society. 1989 ; Vol. 111, No. 14. pp. 5271-5284.
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abstract = "The electrical, optical, and magnetic properties of the partially oxidized, cofacially joined phthalocyanine polymers {[Si(Pc)O]Xy}n are investigated for X- = BF4 -, y = 0.00-0.50; X- = p-toluenesulfonate (TOS-), y = 0.00-0.67; and X- = SO4 2-, y = 0.040, 0.095. As a function of increasing y, the physical properties of the BF4 - and TOS- salts evidence a transition at y ≈ 0.20 from a localized carrier semiconductor or insulator to a molecular metal. Thus, the dc electrical conductivity increases from low values having a temperature dependence most characteristic of disorder and/or hopping transport between localized states to values characteristic of a molecular metal with fluctuation-induced carrier tunneling between relatively large metallike particles. Beyond y ≳ 0.25, the conductivity is only weakly dependent on y. At y ≈ 0.20, the thermoelectric power [S(T)] also changes from behavior characteristic of a p-type semiconductor or insulator to that of a p-type molecular metal. Differences in S(T) between X- = BF4 - and TOS- polymers appear to be due largely to minor structural variations. Optical reflectivity measurements reveal the appearance of a metallike plasma edge at y ≈ 0.20, followed by an incremental shift of this feature to higher energy with further increase in y. The static magnetic susceptibility of {[Si(Pc)O](BF4)y}n evidences an abrupt transition at y ≈ 0.20 from a large concentration of localized, Curie-like spins to Pauli-like behavior characteristic of a molecular metal. Beyond y ≳ 0.30, the Pauli-like susceptibility is nearly independent of y. ESR studies indicate a ligand-centered π-radical-cation electronic structure. For X- = BF4- and TOS-, line-width studies as a function of y evidence a progression from relatively localized to delocalized carriers. It is suggested that the insulator/semiconductor to molecular metal transition in these materials is an Anderson-like transition that arises when the Fermi level crosses a mobility edge from localized states (presumably due to disorder and/or defects) at the tail of the conduction band to delocalized, metallike states. With the possible exception of ESR line-width data, the electrical, optical, and magnetic studies of {[Si(Pc)O] (SO4)0.095}n provide no evidence for an enhanced, carrier-localizing perturbation of the [Si(Pcρ+)O]n band structure by the dinegative off-axis counterions.",
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T1 - Molecular metals with widely tunable band filling. Response of the collective properties of a phthalocyanine molecular metal to drastic excursions in partial oxidation state and charge-compensating counterions

AU - Almeida, Manuel

AU - Gaudiello, John G.

AU - Kellogg, Glen E.

AU - Tetrick, Stephen M.

AU - Marks, Tobin J

AU - McCarthy, William J.

AU - Butler, John C.

AU - Kannewurf, Carl R.

AU - Marks, Tobin J.

PY - 1989

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N2 - The electrical, optical, and magnetic properties of the partially oxidized, cofacially joined phthalocyanine polymers {[Si(Pc)O]Xy}n are investigated for X- = BF4 -, y = 0.00-0.50; X- = p-toluenesulfonate (TOS-), y = 0.00-0.67; and X- = SO4 2-, y = 0.040, 0.095. As a function of increasing y, the physical properties of the BF4 - and TOS- salts evidence a transition at y ≈ 0.20 from a localized carrier semiconductor or insulator to a molecular metal. Thus, the dc electrical conductivity increases from low values having a temperature dependence most characteristic of disorder and/or hopping transport between localized states to values characteristic of a molecular metal with fluctuation-induced carrier tunneling between relatively large metallike particles. Beyond y ≳ 0.25, the conductivity is only weakly dependent on y. At y ≈ 0.20, the thermoelectric power [S(T)] also changes from behavior characteristic of a p-type semiconductor or insulator to that of a p-type molecular metal. Differences in S(T) between X- = BF4 - and TOS- polymers appear to be due largely to minor structural variations. Optical reflectivity measurements reveal the appearance of a metallike plasma edge at y ≈ 0.20, followed by an incremental shift of this feature to higher energy with further increase in y. The static magnetic susceptibility of {[Si(Pc)O](BF4)y}n evidences an abrupt transition at y ≈ 0.20 from a large concentration of localized, Curie-like spins to Pauli-like behavior characteristic of a molecular metal. Beyond y ≳ 0.30, the Pauli-like susceptibility is nearly independent of y. ESR studies indicate a ligand-centered π-radical-cation electronic structure. For X- = BF4- and TOS-, line-width studies as a function of y evidence a progression from relatively localized to delocalized carriers. It is suggested that the insulator/semiconductor to molecular metal transition in these materials is an Anderson-like transition that arises when the Fermi level crosses a mobility edge from localized states (presumably due to disorder and/or defects) at the tail of the conduction band to delocalized, metallike states. With the possible exception of ESR line-width data, the electrical, optical, and magnetic studies of {[Si(Pc)O] (SO4)0.095}n provide no evidence for an enhanced, carrier-localizing perturbation of the [Si(Pcρ+)O]n band structure by the dinegative off-axis counterions.

AB - The electrical, optical, and magnetic properties of the partially oxidized, cofacially joined phthalocyanine polymers {[Si(Pc)O]Xy}n are investigated for X- = BF4 -, y = 0.00-0.50; X- = p-toluenesulfonate (TOS-), y = 0.00-0.67; and X- = SO4 2-, y = 0.040, 0.095. As a function of increasing y, the physical properties of the BF4 - and TOS- salts evidence a transition at y ≈ 0.20 from a localized carrier semiconductor or insulator to a molecular metal. Thus, the dc electrical conductivity increases from low values having a temperature dependence most characteristic of disorder and/or hopping transport between localized states to values characteristic of a molecular metal with fluctuation-induced carrier tunneling between relatively large metallike particles. Beyond y ≳ 0.25, the conductivity is only weakly dependent on y. At y ≈ 0.20, the thermoelectric power [S(T)] also changes from behavior characteristic of a p-type semiconductor or insulator to that of a p-type molecular metal. Differences in S(T) between X- = BF4 - and TOS- polymers appear to be due largely to minor structural variations. Optical reflectivity measurements reveal the appearance of a metallike plasma edge at y ≈ 0.20, followed by an incremental shift of this feature to higher energy with further increase in y. The static magnetic susceptibility of {[Si(Pc)O](BF4)y}n evidences an abrupt transition at y ≈ 0.20 from a large concentration of localized, Curie-like spins to Pauli-like behavior characteristic of a molecular metal. Beyond y ≳ 0.30, the Pauli-like susceptibility is nearly independent of y. ESR studies indicate a ligand-centered π-radical-cation electronic structure. For X- = BF4- and TOS-, line-width studies as a function of y evidence a progression from relatively localized to delocalized carriers. It is suggested that the insulator/semiconductor to molecular metal transition in these materials is an Anderson-like transition that arises when the Fermi level crosses a mobility edge from localized states (presumably due to disorder and/or defects) at the tail of the conduction band to delocalized, metallike states. With the possible exception of ESR line-width data, the electrical, optical, and magnetic studies of {[Si(Pc)O] (SO4)0.095}n provide no evidence for an enhanced, carrier-localizing perturbation of the [Si(Pcρ+)O]n band structure by the dinegative off-axis counterions.

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