Modular Assembly of Vibrationally and Electronically Coupled Rhenium Bipyridine Carbonyl Complexes on Silicon

Abstract

Hybrid inorganic/organic heterointerfaces are promising systems for next-generation photocatalytic, photovoltaic, and chemical-sensing applications. Their performance relies strongly on the development of robust and reliable surface passivation and functionalization protocols with (sub)molecular control. The structure, stability, and chemistry of the semiconductor surface determine the functionality of the hybrid assembly. Generally, these modification schemes have to be laboriously developed to satisfy the specific chemical demands of the semiconductor surface. The implementation of a chemically independent, yet highly selective, standardized surface functionalization scheme, compatible with nanoelectronic device fabrication, is of utmost technological relevance. Here, we introduce a modular surface assembly (MSA) approach that allows the covalent anchoring of molecular transition-metal complexes with subnanometer precision on any solid material by combining atomic layer deposition (ALD) and selectively self-assembled monolayers of phosphonic acids. ALD, as an essential tool in semiconductor device fabrication, is used to grow conformal aluminum oxide activation coatings, down to sub-nanometer thicknesses, on silicon surfaces to enable a selective step-by-step layer assembly of rhenium(I) bipyridine tricarbonyl molecular complexes. The modular surface assembly of molecular complexes generates precisely structured spatial ensembles with strong intermolecular vibrational and electronic coupling, as demonstrated by infrared spectroscopy, photoluminescence, and X-ray photoelectron spectroscopy analysis. The structure of the MSA can be chosen to avoid electronic interactions with the semiconductor substrate to exclusively investigate the electronic interactions between the surface-immobilized molecular complexes.

The Puzzling Question about the Origin of the Second Electron in the Molecular Photocatalytic Reduction of CO2

“…As well as RuRe and RuRe2 , the new supramolecular photocatalysts RuRe3 contains at least one fac ‐Re(dmb)(CO) 3 Cl‐moiety. These groups cause three characteristic Re‐carbonyl vibrational stretching modes, i. e ., the in‐phase symmetric a‘(1), antisymmetric a“, and out of‐phase symmetric a‘(2), present in the FT‐IR spectra (Figure S3) of all three molecules between 1730–2040 cm −1 [11a,13] . Two of these signals (a“, a‘(2)) are not resolved well enough to appear separated.…”

Spatially‐Modulated Silicon Interface Energetics Via Hydrogen Plasma‐Assisted Atomic Layer Deposition of Ultrathin Alumina

“…In this way, the oxide conversion process can be exploited for subsequent (area‐selective) chemical functionalization of the AlO x ‐terminated surface, as recently reported by our group. [ 14e,23 ]…”

Radical-Driven Crystal–Amorphous–Crystal Transition of a Metal–Organic Framework

“…Organic radicals possess one or more unpaired electrons that can endow these molecules with unique properties, including magnetism, electronic conductivity, and optical and redox activities. , Importantly, spin-pairing or through-space electron delocalization through the π-orbital overlap of planar organic radicals provides a unique opportunity to achieve novel structural supramolecular self-assembly. , For example, redox-active molecules such as methyl viologen, bi/terpyridine, , tetrathiafulvalene, tetracyanoquinodimethane, naphthalenediimide (NDI), − and their derivatives have been widely employed for radical-induced supramolecular self-assemblies. The resulting supramolecules showed enhanced radical stabilities and magnified radical-induced optical, electronic, and magnetic properties compared to individual molecules. , …”