Controlling Through-Space and Through-Bond Exchange Pathways in Bis-Cobaltocenes for Molecular Spintronics

10.26434/chemrxiv.9878729.v1 ◽

2019 ◽

Author(s):

Sarah Puhl ◽

Torben Steenbock ◽

Carmen Herrmann ◽

Jürgen Heck

Keyword(s):

Chemical Synthesis ◽

First Principles ◽

Information Transfer ◽

Spin Coupling ◽

Molecular Spintronics ◽

Pathways Analysis ◽

Chemical Strain

Pinching molecules via chemical strain suggests intuitive consequences, such as compression at the pinched site, and clothespin-like opening of other parts of the structure. If this opening affects two spin centers, it should result in reduced communication between them. We show that for a naphthalene-bridged biscobaltocenes with competing through-space and through-bond pathways, the consequences of pinching are far less intuitive: despite the known dominance of through-space interactions, the bridge plays a much larger role for exchange spin coupling than previously assumed. Based on a combination of chemical synthesis, structural, magnetic and redox characterization, and a newly developed first-principles theoretical pathways analysis, we can suggest a comprehensive explanation for this nonintuitive behavior. These results are of interest for molecular spintronics, as naphthalene-linked cobaltocenes can form wires on surfaces for potential spin-only information transfer.

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Computationally Augmented Retrosynthesis: Total Synthesis of Paspaline A and Emindole PB

10.26434/chemrxiv.7322330.v1 ◽

2018 ◽

Author(s):

Timothy Newhouse ◽

Daria E. Kim ◽

Joshua E. Zweig

Keyword(s):

Chemical Synthesis ◽

Total Synthesis ◽

Small Molecules ◽

First Principles ◽

Quantum Chemical ◽

Computational Analysis ◽

Empirical Evaluation ◽

Synthetic Strategy ◽

Catalyzed Reactions ◽

Enzyme Catalyzed Reactions

The diverse molecular architectures of terpene natural products are assembled by exquisite enzyme-catalyzed reactions. Successful recapitulation of these transformations using chemical synthesis is hard to predict from first principles and therefore challenging to execute. A means of evaluating the feasibility of such chemical reactions would greatly enable the development of concise syntheses of complex small molecules. Herein, we report the computational analysis of the energetic favorability of a key bio-inspired transformation, which we use to inform our synthetic strategy. This approach was applied to synthesize two constituents of the historically challenging indole diterpenoid class, resulting in a concise route to (–)-paspaline A in 9 steps from commercially available materials and the first pathway to and structural confirmation of emindole PB in 13 steps. This work highlights how traditional retrosynthetic design can be augmented with quantum chemical calculations to reveal energetically feasible synthetic disconnections, minimizing time-consuming and expensive empirical evaluation.

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Radical based molecular transport system as good molecular spintronics device predicted by first-principles study

Computational Materials Science ◽

10.1016/j.commatsci.2017.03.009 ◽

2017 ◽

Vol 133 ◽

pp. 93-98 ◽

Cited By ~ 2

Author(s):

J. Zhang ◽

K.L. Yao

Keyword(s):

Transport System ◽

First Principles ◽

Molecular Transport ◽

First Principles Study ◽

Molecular Spintronics ◽

Spintronics Device

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The negative 7J(CHO, CH3) in 4-methylbenzaldehyde. Ionicity of the carbonyl bond

Canadian Journal of Chemistry ◽

10.1139/v92-324 ◽

1992 ◽

Vol 70 (10) ◽

pp. 2555-2557

Author(s):

Ted Schaefer ◽

Rudy Sebastian

Keyword(s):

First Principles ◽

Valence Bond ◽

Spin Coupling ◽

Coupling Mechanism ◽

Unexpected Result ◽

Coupling Constant ◽

Valence Bond Structure ◽

Carbonyl Bond ◽

Spin Spin Coupling ◽

Benzaldehyde Derivatives

The spin–spin coupling constant over seven bonds between the formyl and methyl protons in 4-methylbenzaldehyde is −0.030 Hz in CS2/C6D12/TMS, and (−)0.035 Hz in acetone-d6, solutions at 297 K. This unexpected result is rationalized in terms of a spin–spin coupling mechanism attributed to the importance of a valence bond structure with an ionic carbonyl bond. The result again emphasizes the sensitivity to substituent perturbations of the six-bond coupling constant in quasi-planar benzaldehyde derivatives. It can have either sign and presents a challenge to its computation from first principles.

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Indirect Nuclear Spin−Spin Coupling Tensors in Diatomic Molecules: A Comparison of Results Obtained by Experiment and First Principles Calculations

Journal of the American Chemical Society ◽

10.1021/ja9942134 ◽

2000 ◽

Vol 122 (13) ◽

pp. 3197-3205 ◽

Cited By ~ 40

Author(s):

David L. Bryce ◽

Roderick E. Wasylishen

Keyword(s):

Nuclear Spin ◽

First Principles ◽

Diatomic Molecules ◽

Spin Coupling ◽

First Principles Calculations ◽

Comparison Of Results ◽

Spin Spin Coupling

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Computationally Augmented Retrosynthesis: Total Synthesis of Paspaline A and Emindole PB

10.26434/chemrxiv.7322330 ◽

2018 ◽

Author(s):

Timothy Newhouse ◽

Daria E. Kim ◽

Joshua E. Zweig

Keyword(s):

Chemical Synthesis ◽

Total Synthesis ◽

Small Molecules ◽

First Principles ◽

Quantum Chemical ◽

Computational Analysis ◽

Empirical Evaluation ◽

Synthetic Strategy ◽

Catalyzed Reactions ◽

Enzyme Catalyzed Reactions

The diverse molecular architectures of terpene natural products are assembled by exquisite enzyme-catalyzed reactions. Successful recapitulation of these transformations using chemical synthesis is hard to predict from first principles and therefore challenging to execute. A means of evaluating the feasibility of such chemical reactions would greatly enable the development of concise syntheses of complex small molecules. Herein, we report the computational analysis of the energetic favorability of a key bio-inspired transformation, which we use to inform our synthetic strategy. This approach was applied to synthesize two constituents of the historically challenging indole diterpenoid class, resulting in a concise route to (–)-paspaline A in 9 steps from commercially available materials and the first pathway to and structural confirmation of emindole PB in 13 steps. This work highlights how traditional retrosynthetic design can be augmented with quantum chemical calculations to reveal energetically feasible synthetic disconnections, minimizing time-consuming and expensive empirical evaluation.

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Strong spin-filtering and spin-valve effects in a molecular V–C60–V contact

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.3.69 ◽

2012 ◽

Vol 3 ◽

pp. 589-596 ◽

Cited By ~ 6

Author(s):

Mohammad Koleini ◽

Mads Brandbyge

Keyword(s):

Electronic Properties ◽

Electronic Transport ◽

First Principles ◽

Spin Valve ◽

Spin Coupling ◽

First Principles Calculations ◽

Filtering Effect ◽

Majority Spin ◽

Strong Spin ◽

Spin Filtering

Motivated by the recent achievements in the manipulation of C60 molecules in STM experiments, we study theoretically the structure and electronic properties of a C60 molecule in an STM tunneljunction with a magnetic tip and magnetic adatom on a Cu(111) surface using first-principles calculations. For the case of a vanadium tip/adatom, we demonstrate how spin coupling between the magnetic V atoms, mediated by the C60, can be observed in the electronic transport, which display a strong spin-filtering effect, allowing mainly majority-spin electrons to pass (>95%). Moreover, we find a significant change in the conductance between parallel and anti-parallel spin polarizations in the junction (86%) which suggests that STM experiments should be able to characterize the magnetism and spin coupling for these systems.

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