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 [CoII9(H2O)6(OH)3(p-RC6H4AsVO3)2(α-PV2WVI15O56)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, P1̅, a = 25.8088(3) Å, b = 25.8336(3) Å, c = 27.1598(3) Å, α = 78.1282(11)°, β = 61.7276(14)°, γ = 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, P1̅, a = 14.2262(2) Å, b = 24.8597(4) Å, c = 37.9388(4) Å, α = 81.9672(10)°, β = 87.8161(10)°, γ = 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.

Addressing Multiple Resistive States of Polyoxovanadates: Conductivity as a Function of Individual Molecular Redox States

“…Metal-oxo clusters (so-called POMs − ) and their inorganic–organic hybrid derivatives meet in principle the requirements necessary for a possible implementation in resistive switching devices. The as-yet-undeveloped utilization of single, spatially clearly defined POM molecules remains, however, the key challenge to achieving the fundamental breakthrough in the resistive memory-based computer technology.…”

Solvo‐thermal Preparation and Characterization of Two CdII Coordination Polymers Constructed From 2,6‐(1,2,4‐Triazole‐4‐yl)pyridine and 5‐R‐Isophthalic Acid (R = Nitro, Sulfo)

“…Over the past 30 years, coordination compounds have attracted strong interest because they can be synthesized from different metal ions/clusters and multi‐dentate building blocks. These functional materials have shown outstanding property in the fields of photoluminescence, catalysis, gas separation and biomedical study . These coordination polymers have many beautiful topologies structural motifs and can form different dimensional extended coordination frameworks such as one‐, two‐ and three‐ dimensionality.…”

Solvo‐thermal Preparation of One Novel Cadmium(II) Coordination Polymer with 1‐(4‐Aminobenzyl)‐1,2,4‐Triazole and Bi‐functional Photo‐Luminescent Sensing for Acetone and Dichromate

“…These functional materials show excellent performances in photo‐luminescence, catalysis, gas separation, magnetism, storage, and biomedicine research areas . Benefiting from judiciously selective of different metal ions (metal clusters) and organic building blocks, coordination materials has numerous structural diversities, which can lead to possess variable functional properties …”