Dataset Information

Probing Frontier Orbital Energies of {Co₉(P₂W₁₅)₃} Polyoxometalate Clusters at Molecule-Metal and Molecule-Water Interfaces.

ABSTRACT: Functionalization of polyoxotungstates with organoarsonate coligands enabling surface decoration was explored for the triangular cluster architectures of the composition [Co^II₉(H₂O)₆(OH)₃(p-RC₆H₄As^VO₃)₂(?-P^V₂W^VI₁₅O₅₆)₃]^25- ({Co₉(P₂W₁₅)₃}, R = H or NH₂), isolated as Na₂₅[Co₉(OH)₃(H₂O)₆(C₆H₅AsO₃)₂(P₂W₁₅O₅₆)₃]·86H₂O (Na-1; triclinic, P1?, a = 25.8088(3) Å, b = 25.8336(3) Å, c = 27.1598(3) Å, ? = 78.1282(11)°, ? = 61.7276(14)°, ? = 60.6220(14)°, V = 13888.9(3) Å³, Z = 2) and Na₂₅[Co₉(OH)₃(H₂O)₆(H₂NC₆H₄AsO₃)₂(P₂W₁₅O₅₆)₃]·86H₂O (Na-2; triclinic, P1?, a = 14.2262(2) Å, b = 24.8597(4) Å, c = 37.9388(4) Å, ? = 81.9672(10)°, ? = 87.8161(10)°, ? = 76.5409(12)°, V = 12920.6(3) Å³, Z = 2). The axially oriented para-aminophenyl groups in 2 facilitate the formation of self-assembled monolayers on gold surfaces and thus provide a viable molecular platform for charge transport studies of magnetically functionalized polyoxometalates. The title systems were isolated and characterized in the solid state, in aqueous solutions, and on metal surfaces. Using conducting tip atomic force microscopy, the energies of {Co₉(P₂W₁₅)₃} frontier molecular orbitals in the surface-bound state were found to directly correlate with cyclic voltammetry data in aqueous solution.

SUBMITTER: Yi X

PROVIDER: S-EPMC5649444 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

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Publications

Probing Frontier Orbital Energies of {Co9(P2W15)3} Polyoxometalate Clusters at Molecule-Metal and Molecule-Water Interfaces.

Yi Xiaofeng X Izarova Natalya V NV Stuckart Maria M Guérin David D Thomas Louis L Lenfant Stéphane S Vuillaume Dominique D van Leusen Jan J Duchoň Tomáš T Nemšák Slavomír S Bourone Svenja D M SDM Schmitz Sebastian S Kögerler Paul P

Journal of the American Chemical Society 20170927 41

Functionalization of polyoxotungstates with organoarsonate coligands enabling surface decoration was explored for the triangular cluster architectures of the composition [CoII9(H2O)6(OH)3(p-RC6H4AsVO3)2(α-PV2WVI15O56)3]25- ({Co9(P2W15)3}, R = H or NH2), isol ...[more]

PMID: 28901755

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Project description:A central issue in understanding redox properties of iron-sulfur proteins is determining the factors that tune the reduction potentials of the Fe-S clusters. Recently, Solomon and coworkers have shown that the Fe-S bond covalency of protein analogs measured by %L, the percent ligand character of the Fe 3d orbitals, from ligand K-edge X-ray absorption spectroscopy (XAS) correlates with the electrochemical redox potentials. Also, Wang and coworkers have measured electron detachment energies for iron-sulfur clusters without environmental perturbations by gas-phase photoelectron spectroscopy (PES). Here the correlations of the ligand character with redox energy and %L character are examined in [Fe(4)S(4)L(4)](2-) clusters with different ligands by broken symmetry density functional theory (BS-DFT) calculations using the B3LYP functional together with PES and XAS experimental results. These gas-phase studies assess ligand effects independently of environmental perturbations and thus provide essential information for computational studies of iron-sulfur proteins. The B3LYP oxidation energies agree well with PES data, and the %L character obtained from natural bond orbital analysis correlates with XAS values, although it systematically underestimates them because of basis set effects. The results show that stronger electron-donating terminal ligands increase %L(t), the percent ligand character from terminal ligands, but decrease %S(b), the percent ligand character from the bridging sulfurs. Because the oxidized orbital has significant Fe-L(t) antibonding character, the oxidation energy correlates well with %L(t). However, because the reduced orbital has varying contributions of both Fe-L(t) and Fe-S(b) antibonding character, the reduction energy does not correlate with either %L(t) or %S(b). Overall, BS-DFT calculations together with XAS and PES experiments can unravel the complex underlying factors in the redox energy and chemical bonding of the [4Fe-4S] clusters in iron-sulfur proteins.

Dataset Information

Probing Frontier Orbital Energies of {Co₉(P₂W₁₅)₃} Polyoxometalate Clusters at Molecule-Metal and Molecule-Water Interfaces.

Publications

Probing Frontier Orbital Energies of {Co<sub>9</sub>(P<sub>2</sub>W<sub>15</sub>)<sub>3</sub>} Polyoxometalate Clusters at Molecule-Metal and Molecule-Water Interfaces.

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