Synthesis and Surface Attachment of Molecular Re(I) Hydride Species with Silatrane Functionalized Bipyridyl Ligands

Abstract

Three molecular Re hydrides of the form (Rbpy)Re(CO)3H with 2,2′-bipyridine (bpy) ligands containing silatrane functional groups for surface attachment on metal oxide surfaces were synthesized. IR spectroscopy and cyclic voltammetry (CV) demonstrated that the complexes containing the silatrane functional groups have electronic properties similar to those of a control compound, which did not contain functional groups for attachment. Additionally, in a similar fashion to the control compound, the silatrane containing Re hydrides are electrocatalysts for the reduction of CO2 to CO in solution. The silatrane containing complexes were immobilized on a thin layer of TiO2 on Si, and the resulting composites were characterized using X-ray photoelectron and IR spectroscopy as well as cyclic voltammetry in the dark and under illumination. Control experiments indicated that the hydride complexes are not stable on the surface and degrade to species which contain a bpy ligand, three CO ligands, and an unknown ligand in the sixth site. Similarly, when one of the silatrane containing Re hydride complexes was immobilized on Si nanoparticles with a thin layer of SiO2 or silica nanoparticles, the hydride ligand was lost. Density functional theory calculations were used to corroborate the observed behavior of hydride species on a surface. Overall, this work demonstrates the difficulties associated with attaching well-defined molecular hydride complexes to metal oxide surfaces.

Methyl Termination of p-Type Silicon Enables Selective Photoelectrochemical CO2 Reduction by a Molecular Ruthenium Catalyst

“…Linear sweep and cyclic voltammetry studies showed that this system achieves a 460 mV photovoltage, which mitigates most of the electrochemical energy requirement necessary to activate this high-overpotential catalyst. This is a significant photovoltage in comparison with similar single-junction p-Si systems with a molecular catalyst. ,− Controlled potential photoelectrolysis over 1 h in a CO 2 -saturated solution yielded CO as the singular product with 87% Faradaic efficiency, consistent with the reactivity obtained at metallic electrodes. The CH 3 -Si performance was stable over the course of the experiment, sustaining a consistent current density.…”

Photoelectrochemical Proton-Coupled Electron Transfer of TiO2 Thin Films on Silicon

“…As part of efforts in The Center for Hybrid Approaches in Solar Energy to Liquid Fuels (CHASE), we have been exploring the immobilization of molecular catalysts on silicon (Figure a). ,, The combination of tunable molecular catalysts with robust and abundant light absorbers such as silicon has the potential for selective and durable solar energy conversions. Silicon surfaces, however, are reactive under ambient conditions and often require a thin protective layer to avoid the formation of an insulating SiO 2 layer.…”

Tricarbonyl rhenium(i) complexes with 8-hydroxyquinolines: structural, chemical, antibacterial, and anticancer characteristics

“…Tricarbonyl rhenium( i ) complexes are the most frequently studied Re compounds, and the 2 + 1 mixed-ligand arrangement of Re(CO) 3 complexes (one ligand is bidentate, and the other is monodentate) is the most frequently considered. 18–26 Several investigations showed the potential anticancer activity of Re(CO) 3 , better than used Pt-drugs, as well as their significant antimicrobial effects. 27–33 On the other hand, 8-hydroxyquinoline and its derivatives are popular organic compounds used as medicines, e.g.…”