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Design of robust 2,2′-bipyridine ligand linkers for the stable immobilization of molecular catalysts on silicon(111) surfaces

Johnson, Samantha I. and Blakemore, James D. and Brunschwig, Bruce S. and Lewis, Nathan S. and Gray, Harry B. and Goddard, William A., III and Persson, Petter (2021) Design of robust 2,2′-bipyridine ligand linkers for the stable immobilization of molecular catalysts on silicon(111) surfaces. Physical Chemistry Chemical Physics, 23 (16). pp. 9921-9929. ISSN 1463-9076. doi:10.1039/d1cp00545f.

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The attachment of the 2,2′-bipyridine (bpy) moieties to the surface of planar silicon(111) (photo)electrodes was investigated using ab initio simulations performed on a new cluster model for methyl-terminated silicon. Density functional theory (B3LYP) with implicit solvation techniques indicated that adventitious chlorine atoms, when present in the organic linker backbone, led to instability at very negative potentials of the surface-modified electrode. In prior experimental work, chlorine atoms were present as a trace surface impurity due to required surface processing chemistry, and thus could plausibly result in the observed surface instability of the linker. Free energy calculations for the Cl-atom release process with model silyl-linker constructs revealed a modest barrier (14.9 kcal mol⁻¹) that decreased as the electrode potential became more negative. A small library of new bpy-derived structures has additionally been explored computationally to identify strategies that could minimize chlorine-induced linker instability. Structures with fluorine substituents are predicted to be more stable than their chlorine analogues, whereas fully non-halogenated structures are predicted to exhibit the highest stability. The behavior of a hydrogen-evolving molecular catalyst Cp*Rh(bpy) (Cp* = pentamethylcyclopentadienyl) immobilized on a silicon(111) cluster was explored theoretically to evaluate differences between the homogeneous and surface-attached behavior of this species in a tautomerization reaction observed under reductive conditions for catalytic H₂ evolution. The calculated free energy difference between the tautomers is small, hence the results suggest that use of reductively stable linkers can enable robust attachment of catalysts while maintaining chemical behavior on the electrode similar to that exhibited in homogeneous solution.

Item Type:Article
Related URLs:
URLURL TypeDescription
Johnson, Samantha I.0000-0001-6495-9892
Blakemore, James D.0000-0003-4172-7460
Brunschwig, Bruce S.0000-0002-6135-6727
Lewis, Nathan S.0000-0001-5245-0538
Gray, Harry B.0000-0002-4453-9716
Goddard, William A., III0000-0003-0097-5716
Persson, Petter0000-0001-7600-3230
Additional Information:© the Owner Societies 2021. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Submitted 05 Feb 2021; Accepted 06 Apr 2021; First published 06 Apr 2021. Research at Caltech was supported by the National Science Foundation Center for Chemical Innovation Solar Fuels (NSF CHE-1305124). S. I. J. was supported by a National Science Foundation Graduate Research Fellowship (Grant No. DGE-1144469), a National Science Foundation Graduate Research Opportunities Worldwide Grant, and by the generous support of the Resnick Sustainability Institute. S. I. J. and P. P. were supported by the Swedish Research Council (VR). W. A. G. was partially supported by the Liquid Sunlight Alliance, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub under Award Number DE-SC0021266. P. P. acknowledges the Swedish Energy Agency (STEM) as well as the Swedish supercomputing facilities LUNARC and NSC for support. S. I. J. thanks Drs. Robert J. Nielsen and Noah Plymale for helpful discussions. S. I. J. and P. P. thank Drs. Lisa A. Fredin and Marta Galynska for helpful discussions. There are no conflicts to declare.
Group:Resnick Sustainability Institute
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1144469
Resnick Sustainability InstituteUNSPECIFIED
Swedish Research CouncilUNSPECIFIED
Department of Energy (DOE)DE-SC0021266
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Issue or Number:16
Record Number:CaltechAUTHORS:20210421-170248147
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Official Citation:Design of robust 2,2′-bipyridine ligand linkers for the stable immobilization of molecular catalysts on silicon(111) surfaces. Phys. Chem. Chem. Phys., 2021, 23, 9921-9929; DOI: 10.1039/d1cp00545f
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108796
Deposited By: Tony Diaz
Deposited On:22 Apr 2021 17:45
Last Modified:06 Jun 2021 04:31

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