Generation of spin in single cholesterol molecules on gold

Karan, Sujoy; Berndt, Richard

doi:10.1039/c5cp07410j

Cited by 11 publications

(13 citation statements)

References 43 publications

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“…Once the tip is brought into contact with the iron center, the spectrum (light blue) develops a dip as typical of the Kondo effect. , Further approach of the tip does not change the shape of the spectrum until destruction of the junction occurs. The spectrum may be fit by a Frota line , (red curve) as expected for the spin-1/2 Kondo effect. − Our fit points out a Kondo temperature about 96 K (this value may differ from the actual Kondo temperature) in good agreement with previous reports on similar molecules. This large value translates into a field of exceeding 15 Tesla to split the Kondo peak, unattainable in STM setups.…”

supporting

confidence: 86%

Spin Control Induced by Molecular Charging in a Transport Junction

et al. 2017

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The ability of molecules to maintain magnetic multistability in nanoscale-junctions will determine their role in downsizing spintronic devices. While spin-injection from ferromagnetic leads gives rise to magnetoresistance in metallic nanocontacts, nonmagnetic leads probing the magnetic states of the junction itself have been considered as an alternative. Extending this experimental approach to molecular junctions, which are sensitive to chemical parameters, we demonstrate that the electron affinity of a molecule decisively influences its spin transport. We use a scanning tunneling microscope to trap a meso-substituted iron porphyrin, putting the iron center in an environment that provides control of its charge and spin states. A large electron affinity of peripheral ligands is shown to enable switching of the molecular S = 1 ground state found at low electron density to S = / at high density, while lower affinity keeps the molecule inactive to spin-state transition. These results pave the way for spin control using chemical design and electrical means.

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confidence: 86%

Spin Control Induced by Molecular Charging in a Transport Junction

et al. 2017

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“…From DFT geometry optimization the calculated cholesterol-to-cyano length of PE1-CN-Chol is determined to be 3.76 nm. The measured distance between cholesterol lamellae, d = 6.68 nm, supports self-assembly into a head-to-head pair via dipole−dipole interactions between CN groups as previously observed for cholesterol on Au, [37,38] and cholesteryl esters on HOPG. [39−41] The calculated dimensions c, d, and ΔL are in good agreement with STM results (Table 1).…”

Section: Scanning Tunneling Microscopy (Stm)supporting

confidence: 82%

Nanoscale Organization of a Platinum(II) Acetylide Cholesteric Liquid Crystal Molecular Glass for Photonics Applications

Cooper

Haley

Long

et al. 2020

Adv Funct Materials

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The fabrication, molecular structure, and spectroscopy of a stable cholesteric liquid crystal platinum acetylide glass obtained from trans-Pt(PEt 3) 2 (CC− C 6 H 5 −CN)(CC−C 6 H 5 −COO−Cholesterol), are described and designated as PE1-CN-Chol. Polarized optical microscopy, differential scanning calorimetry, and wide-angle X-ray scattering experiments show room temperature glassy/ crystalline texture with crystal formation upon heating to 165 °C. Further heating results in conversion to cholesteric phase. Cooling to room temperature leads to the formation of a cholesteric liquid crystal glass. Scanning tunneling microscopy of a PE1-CN-Chol monolayer reveals self-assembly at the solid−liquid interface with an array of two molecules arranged in pairs, oriented head-to-head through the CN groups, giving rise to a lamella arrangement. The lamella structure obtained from molecular dynamics calculations shows a clear phase separation between the conjugated platinum acetylide and the hydrophobic cholesterol moiety with the lamellae separation distance being 4.0 nm. Ultrafast transient absorption and flash photolysis spectra of the glass show intersystem crossing to the triplet state occurring within 100 ps following excitation. The triplet decay time of the film compared to aerated and deoxygenated solutions is consistent with oxygen quenching at the film surface but not within the film. The high chromophore concentration, high glass thermal stability, and long triplet lifetime in air show that these materials have potential as nonlinear absorbing materials.

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“…The proposed mechanism is consistent with all experimental observations. In recent STM manipulation experiments, cholesterol, a molecule with a cyclohexene group embedded into several cyclohexane groups, has likewise been switched into a state displaying a Kondo effect . On some other molecules with a cyclohexene unit like shikimic acid related attempts remained without success.…”

Section: Methodsmentioning

confidence: 99%

Spin in a Closed‐Shell Organic Molecule on a Metal Substrate Generated by a Sigmatropic Reaction

Lorente¹,

Bocquet

Berndt

et al. 2018

Angew Chem Int Ed

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Inert metal surfaces present more chances of hosting organic intact radicals than other substrates, but large amounts of delocalized electronic states favor charge transfer and thus spin quenching. Lowering the molecule–substrate interaction is a usual strategy to stabilize radicals on surfaces. In some works, thin insulating layers were introduced to provide a controllable degree of electronic decoupling. Recently, retinoid molecules adsorbed on gold have been manipulated with a scanning tunneling microscope (STM) to exhibit a localized spin, but calculations failed to find a radical derivative of the molecule on the surface. Now the formation of a neutral radical spatially localized in a tilted and lifted cyclic end of the molecule is presented. An allene moiety provokes a perpendicular tilt of the cyclic end relative to the rest of the conjugated chain, thus localizing the spin of the dehydrogenated allene in its lifted subpart. DFT calculations and STM manipulations give support to the proposed mechanism.

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Generation of spin in single cholesterol molecules on gold

Cited by 11 publications

References 43 publications

Spin Control Induced by Molecular Charging in a Transport Junction

Spin Control Induced by Molecular Charging in a Transport Junction

Nanoscale Organization of a Platinum(II) Acetylide Cholesteric Liquid Crystal Molecular Glass for Photonics Applications

Spin in a Closed‐Shell Organic Molecule on a Metal Substrate Generated by a Sigmatropic Reaction

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