Molecular Electronics Research Articles

A strategy for covalent anchoring of self-assembling β3 oligoamide nanorods to gold surfaces

Abstract Oligopeptides stand out for their remarkable structural variability, ease of synthesis, and amenability to functionalization, making them exceedingly appealing for crafting functional nanostructured materials. The low metabolic stability of natural peptides can be overcome by replacing α-amino acids with β3- amino acids, to yield artificial peptides best described as substituted β3-oligoamides. Controlling the morphology of such structures by varying the amino acid residues and altering the oligoamide termini makes it possible to adapt the core design to a range of hierarchical structures and function. Conductivity is a desired property in such nanomaterials; preferably conductive materials should be chemically anchored to a highly conductive metal, such as gold surface to connect to macroscopic electronics. It is preferable to use thiol functionality, however β3 cysteine is not synthetically achieveable. In this study β3 [SLIA] oligoamide has been synthesized and functionalized at the N terminus with a thiol moiety. After successful synthesis and purification, the thiolated oligoamide was physically characterized to confirm binding to gold, self-assembly and hetero assembly on these anchor points. It was demonstrated with a quartz crystal microbalance (QCM) that self-assembling monolayers can be formed on a gold surface and the formation of a S-Au bond was confirmed with X-ray photoelectron spectroscopy. Growth of Ac-β3[WKLWEL] fibres on these anchor points was confirmed by using atomic force microscopy and QCM. Hence, a viable metal anchor has been established that lays the foundations for the future development of molecular electronics based on β3 oligoamides.

The role of microfaceting in heteroepitaxial interfaces

We investigate the effects of microfaceting on the orientation and interface structure of fcc films on fcc substrates by molecular dynamics simulations and atomic resolution electron microscopy. For (110) substrates, the simulations reveal a misorientation between film and substrate lattices that undergoes a sudden change when interfacial facets approach the “magic size”, where a lattice dislocation minimizes the strain energy by compensating the misfit between film and substrate. For a large misfit, the angle of misorientation varies between zero and several degrees, depending on the size and sequence of microfacets. Experimental observations of interfaces in Ag/Ni near the Ni(110) orientation uncover the presence of magic-size {111} facets and show how microfaceting controls the partitioning of misfit dislocations. For facets smaller than the magic size, misfit may be compensated by partial rather than perfect dislocations. In vicinal {hhl} interfaces, made of {111} terraces separated by single-layer steps, a partial dislocation per terrace leads to film growth in the heterotwin orientation. This concept explains a range of previous results on interface structures in a variety of heteroepitaxial systems.

Synthesis, Molecular Electron Density Theory Study, Molecular Docking, and Pharmacological Evaluation of New Coumarin-Sulfonamide-Nitroindazolyl-Triazole Hybrids as Monoamine Oxidase Inhibitors.

Inhibitors of monoamine oxidases (MAOs) are of interest for the treatment of neurodegenerative disorders and other human pathologies. In this frame, the present work describes different synthetic strategies to obtain MAO inhibitors via the coupling of the aminocoumarin core with arylsulfonyl chlorides followed by copper azide-alkyne cycloaddition, leading to coumarin-sulfonamide-nitroindazolyl-triazole hybrids. The nitration position on the coumarin moiety was confirmed through nuclear magnetic resonance spectroscopy and molecular electron density theory in order to elucidate the molecular mechanism and selectivity of the electrophilic aromatic substitution reaction. The coumarin derivatives were evaluated for their inhibitory potency against monoamine oxidases and cholinesterases. Molecular docking calculations provided a rational binding mode of the best compounds in the series with MAO A and B. The work identified hybrids 14a-c as novel MAO inhibitors, with a selective action against isoform B, of potential interest to combat neurological diseases.

Novel series of hydrazones carrying pyrazole and triazole moiety: Synthesis, structural elucidation, quantum computational studies and antiviral activity against SARS-Cov-2

The novel series of hydrazones carrying both pyrazole and triazole moiety were synthesized and characterized using single crystal X-ray diffraction studies. It is found that the compound crystallizes in the triclinic system in the space group P1̅. Hirshfeld analysis was carried out to visualize the noncovalent intermolecular interactions which are responsible for molecular packing in the crystal. Further, density functional theory (DFT) calculations were used to calculate optimized molecular structure, stability, and a few of the quantum chemical parameters. Derived results are in good agreement with the experimentally obtained results. Analysis of frontier molecular orbitals (HOMO and LUMO) and their energy gap of the optimized structure revealed that the compound is stable in the gaseous state. Molecular electron densities, and electrostatic potential maps provide the reactive site and charge distribution of triazole group. Quantum theory of atoms in molecules (QTAIM) and reduced density gradient (RDG) analysis were carried out to explore the weak interactions present in the molecule. In addition, the synthesized compound was investigated as an inhibitor for SARS CoV-2 protease using in-silico molecular docking analysis to understand the mode of binding. The docking results showed the good binding score with Mpro protease 6LU7. Further, molecular dynamics (MD) were carried out for the best hit docked complexes.

ESIPT-associated fluorescent property and AIE characteristic of multifunctional nanoprobe DPNAP

The DPNAP is a multifunctional nanoprobe designed for selective illumination of fungi and targeted antimicrobial applications. By introducing hydroxyl groups into the DPNAP, the aggregation-induced emission (AIE) characteristic can be obtained. However, its optical properties and underlying theoretical mechanisms are not fully understood. In this work, we explored the stable DPNAP configurations by constructing the potential energy surfaces and elucidated the mechanism of the proton transfer reaction. Our findings indicate that proton transfer occurs through a stepwise reaction with energy barriers of < 10 kcal/mol, owing to the variation in hydrogen-bonding strength as revealed by hydrogen-bond parameters and infrared vibrational analyses. The theoretical fluorescence peak (λcal = 541 nm) based on the optimized structures is consistent with the experimental peak (λexp = 500 nm). The experimental single-fluorescence band is attributed to the overlap of emission spectra of normal structure and single- and double-proton transfer isomers. Moreover, the hydroxyl-induced AIE mechanism is attributed to increased molecular planarity and restricted intramolecular charge transfer in the aggregate state. Understanding of the AIE characteristic and ESIPT mechanism is of fundamental importance in molecular electronics and photonics, and is also beneficial to the development of novel biomedical materials.

Optical Laser Tweezer‐Directed Single Particle Solvatochromism of Conjugated Polydiacetylene

Solvatochromism plays a pivotal role in various scientific and technological fields including those that explore molecular interactions, sensing technologies, and organic electronics. Notably, despite their ease of manipulation, direct visualization, and potential for single particle‐based sensing, micro‐sized solid particles have been the focus of a surprisingly low number of solvatochromism investigations. In this study, polydiacetylene (PDA) particles are synthesized and their solvatochromism is investigated at the single particle level using optical laser tweezers‐based methods. The findings reveal that unpolymerized monomers within PDA particles at the water/n‐decane interface undergo dissolution in the n‐decane phase to form internal voids in the particles. This phenomenon leads to structural deformation of the PDA which triggers a solvatochromic response. Studies that integrate this phenomenon with established particle‐based methodologies should provide deeper insights into diverse chromism behaviors and potential applications of solvatochromic materials.

Low-Migration Compounds with Amine Functionality as Coinitiators of Radical Polymerization.

The utilization of two-component systems comprising camphorquinone (CQ) and aromatic amines has become prevalent in the photopolymerization. However, there are still concerns about the safety of this CQ/amine system, mainly because of the toxicity associated with the leaching of aromatic amines. In light of these concerns, this study aims to develop novel coinitiator combinations featuring CQ and amines which cannot be leached out of materials, enabling free radical polymerization of representative dentalmethacrylate resins under blue light irradiation. This approach involves the initial design and analysis of hydrogen donors with low C─H bond dissociation energy through molecular modeling. Subsequently, copolymerizable methacrylate functional groups are incorporated via chemical modification, allowing it to act as both coinitiator and copolymerization monomer to achieve low migrationand leachability properties. This work presents, for the first time, the synthesis of the innovative coinitiator and compares its performance with the benchmark CQ/ethyl-4-dimethylaminobenzoate (EDB)-based photoinitiation system (PIS). The results demonstrate the effectiveness of the newly proposed PIS. Finally, an in-depth investigation is conducted into the reaction mechanism associated with this PIS through molecular orbital calculations and electron spin resonance studies.

The laser pump X-ray probe system at LISA P08 PETRA III.

Understanding and controlling the structure and function of liquid interfaces is a constant challenge in biology, nanoscience and nanotechnology, with applications ranging from molecular electronics to controlled drug release. X-ray reflectivity and grazing incidence diffraction provide invaluable probes for studying the atomic scale structure at liquid-air interfaces. The new time-resolved laser system at the LISA liquid diffractometer situated at beamline P08 at the PETRA III synchrotron radiation source in Hamburg provides a laser pump with X-ray probe. The femtosecond laser combined with the LISA diffractometer allows unique opportunities to investigate photo-induced structural changes at liquid interfaces on the pico- and nanosecond time scales with pump-probe techniques. A time resolution of 38 ps has been achieved and verified with Bi. First experiments include laser-induced effects on salt solutions and liquid mercury surfaces with static and varied time scales measurements showing the proof of concept for investigations at liquid surfaces.

Long-Range Gating in Single-Molecule One-Dimensional Topological Insulators.

Single-molecule one-dimensional topological insulator (1D TI) is a class of molecular wires that exhibit increasing conductance with wire length. This unique trend is due to the coupling between the two low-lying topological edge states of 1D TIs described by the Su-Schrieffer-Heeger model. In principle, this quantum phenomenon within 1D TIs can be utilized to achieve long-range gating in molecular conductors. Here, we study electron transport through a single-edge state of doubly oxidized oligophenylene bis(triarylamine) to understand the effect of the edge state coupling on conductance. We find that conductance is elevated by approximately 1 order of magnitude compared to a control molecule with the same conductance pathway. Density function theory calculations further support that the increase in conductance is due to the interaction between the edge states of 1D TIs. This work demonstrates a new gating paradigm in molecular electronics, while also providing a deeper understanding of how edge states interact and affect electron transport within 1D TIs.

Empagliflozin Improves Diastolic Function in HFpEF by Restabilizing the Mitochondrial Respiratory Chain.

Clinical studies demonstrated beneficial effects of sodium-glucose-transporter 2 inhibitors on the risk of cardiovascular death in patients with heart failure with preserved ejection fraction (HFpEF). However, underlying processes for cardioprotection remain unclear. The present study focused on the impact of empagliflozin (Empa) on myocardial function in a rat model with established HFpEF and analyzed underlying molecular mechanisms. Obese ZSF1 (Zucker fatty and spontaneously hypertensive) rats were randomized to standard care (HFpEF, n=18) or Empa (HFpEF/Empa, n=18). ZSF1 lean rats (con, n=18) served as healthy controls. Echocardiography was performed at baseline and after 4 and 8 weeks, respectively. After 8 weeks of treatment, hemodynamics were measured invasively, mitochondrial function was assessed and myocardial tissue was collected for either molecular and histological analyses or transmission electron microscopy. In HFpEF Empa significantly improved diastolic function (E/é: con: 17.5±2.8; HFpEF: 24.4±4.6; P<0.001 versus con; HFpEF/Empa: 19.4±3.2; P<0.001 versus HFpEF). This was accompanied by improved hemodynamics and calcium handling and by reduced inflammation, hypertrophy, and fibrosis. Proteomic analysis demonstrated major changes in proteins involved in mitochondrial oxidative phosphorylation. Cardiac mitochondrial respiration was significantly impaired in HFpEF but restored by Empa (Vmax complex IV: con: 0.18±0.07 mmol O2/s/mg; HFpEF: 0.13±0.05 mmol O2/s/mg; P<0.041 versus con; HFpEF/Empa: 0.21±0.05 mmol O2/s/mg; P=0.012 versus HFpEF) without alterations of mitochondrial content. The expression of cardiolipin, an essential stability/functionality-mediating phospholipid of the respiratory chain, was significantly decreased in HFpEF but reverted by Empa (con: 15.9±1.7 nmol/mg protein; HFpEF: 12.5±1.8 nmol/mg protein; P=0.002 versus con; HFpEF/Empa: 14.5±1.8 nmol/mg protein; P=0.03 versus HFpEF). Transmission electron microscopy revealed a reduced size of mitochondria in HFpEF, which was restored by Empa. The study demonstrates beneficial effects of Empa on diastolic function, hemodynamics, inflammation, and cardiac remodeling in a rat model of HFpEF. These effects were mediated by improved mitochondrial respiratory capacity due to modulated cardiolipin and improved calcium handling.

Rational Design and Engineering of Terminal Functional Groups in Dibenzothiophene‐Diphenylamine Small Molecular Electron Donors for Enhanced Photovoltaic Efficiency in All‐Small‐Molecule Organic Solar Cells

AbstractAll‐small‐molecule organic solar cells (ASM‐OSCs) offer advantages like well‐defined molecular structures and excellent reproducibility. However, lower photovoltaic efficiencies hinder their adoption due to limitations in designing small molecular electron donors (SMEDs) with optimal energy levels, light absorption, and optoelectronic properties. The present study addresses this gap by rationally designing a series of SMEDs (DBT‐2FA1 to DBT‐2FA6) through terminal acceptors engineering into dibenzothiophene core with diphenylamine side donors for potential applications in ASM‐OSCs. Density functional theory simulations are carried‐out to establish structure‐property relationships based on structural, electrochemical, photophysical, and charge transfer (CT) properties. Results show that the SMEDs exhibit low‐lying HOMOs for suitable energy level alignment with benchmark Y6 acceptor, promoting open‐circuit voltage and charge separation. The panchromatic absorption spectra covering Vis‐NIR region and maximum light harvesting efficiency are beneficial for high current‐density in ASM‐OSCs. Notably, the push‐pull mechanism within SMEDs results in dominant intramolecular CT with above 70% CT excitations. Whereas, a moderate variation in dipole moments and electrostatic potential differences with acceptor material led to 99.9% intermolecular CT, thus ensuring robust exciton dissociation and efficient photocurrent generation. Overall, this work provides a molecular‐level understanding of designing novel SMEDs and their compatibility with acceptor materials for developing future high‐performance ASM‐OSCs.

DFT, Molecular Docking, Bioactivity and ADME Analyses of Vic-dioxim Ligand Containing Hydrazone Group and its Zn(II) Complex.

Cancer is one of the diseases affecting a large population worldwide and resulting in death. Finding new anti-cancer drugs that are target-focused and have low toxicity is of great importance. This study aimed to investigate the effects of vic-dioxime derivatives carrying hydrazone group and its Zn(II) complex on cancer using molecular docking, bioactivity and quantum chemical calculations. Molecular docking studies were performed on epidermal growth factor receptor and vascular endothelial growth factor receptor 2 target proteins. Furthermore, molecular geometry was performed, and the frontier molecular orbitals, Mulliken charges and molecular electron density distribution were evaluated using density functional theory. Also, the bioactivity parameters of the compounds were evaluated, and ADME analysis was performed using web-based tools. Higher binding affinity was observed for Zn(II) complex with target proteins vascular endothelial growth factor receptor 2 and against epidermal growth factor receptor when compared with LH2. Only the Zn(II) complex against the epidermal growth factor receptor had ligand efficiency and fit quality in the valid range. Furthermore, LH2 has the most potent electrophilic ability (acceptor) among other compounds. Moreover, both LH2 and Zn(II) complexes strongly satisfy Lipinski's rule of five. In conclusion, these novel compounds, especially Zn(II) complex, can be new candidates for anticancer drug development studies which are target-focused and have low toxicity.

Three distinct conductance states in polycyclic aromatic hydrocarbon derivatives.

Tight-binding model (TBM) and density functional theory (DFT) calculations were employed. Both simulations have demonstrated that the electrical conductance for eight polycyclic aromatic hydrocarbons (PAHs) can be modulated by varying the number of aromatic rings (NAR) within the aromatic derivatives. TBM simulations reveal three distinct conductance states: low, medium and high for the studied PAH derivatives. The three distinct conductance states suggested by TBM are supported by DFT transmission curves, where the low conductance evidenced by T(E) = 0, for benzene, naphthalene, pyrene and anthracene. While azulene and anthanthrene exhibit a medium conductance as T(E) = 1, and tetracene and dibenzocoronene possess a high conductance with T(E) = 2. Low, medium and high values were elucidated according to the energy gap E g and E g gaps are strongly dependent on the NAR in the PAH derivatives. This study also suggests that any PAH molecules are a conductor if E g < 0.20 eV. A linear relationship between the conductance and NAR (G ∝ NAR) was found and conductance follows the order G (benzene, 1 NAR) < G (anthanthrene, 4 NAR) < G (dibenzocoronene, 9 NAR). The proposed study suggests a relevant step towards the practical application of molecular electronics and future device application.

Alternant Hydrocarbon Diradicals as Optically Addressable Molecular Qubits.

High-spin molecules allow for bottom-up qubit design and are promising platforms for magnetic sensing and quantum information science. Optical addressability of molecular electron spins has also been proposed in first-row transition-metal complexes via optically detected magnetic resonance (ODMR) mechanisms analogous to the diamond-nitrogen-vacancy color center. However, significantly less progress has been made on the front of metal-free molecules, which can deliver lower costs and milder environmental impacts. At present, most luminescent open-shell organic molecules are π-diradicals, but such systems often suffer from poor ground-state open-shell characters necessary to realize a stable ground-state molecular qubit. In this work, we use alternancy symmetry to selectively minimize radical-radical interactions in the ground state, generating π-systems with high diradical characters. We call them m-dimers, referencing the need to covalently link two benzylic radicals at their meta carbon atoms for the desired symmetry. Through a detailed electronic structure analysis, we find that the excited states of alternant hydrocarbon m-diradicals contain important symmetries that can be used to construct ODMR mechanisms leading to ground-state spin polarization. The molecular parameters are set in the context of a tris(2,4,6-trichlorophenyl)methyl (TTM) radical dimer covalently tethered at the meta position, demonstrating the feasibility of alternant m-diradicals as molecular color centers.

Revealing the mechanism, Regio- and stereo selectivity and solvent effects of [3 + 2] cycloaddition reactions involving N-benzyl fluoro nitrone and electron-deficient alkynes

The [3 + 2] cycloaddition reactions (32CA) between N-benzyl fluoro nitrone and electron-deficient dipolarophiles alkynes have been studied using molecular electron density theory at the B3LYP-D3/6-31G(d) level. The findings indicate that, in these 32CA reactions, a one-step mechanism is in play with asynchronous transition states. The topological analyses of these transition states are consistent with the presence of non-covalent interactions at the bonding regions between atoms. The analysis of the energy profile in gas phase and in the presence of solvents indicates a preference for a specific site addition over the others. Parr functions were thus used to justify such regioselectivity. In addition, we show that solvents do not modify the regioselectivity achieved, but it increases the activation energies and reduces the exothermic nature of this 32CA reaction. The present findings are in agreement with the experimental results.

Unraveling redox pathways of the disulfide bond in dimethyl disulfide: Ab initio modeling.

In cellular environments, the reduction of disulfide bonds is pivotal for protein folding and synthesis. However, the intricate enzymatic mechanisms governing this process remain poorly understood. This study addresses this gap by investigating a disulfide bridge reduction reaction, serving as a model for comprehending electron and proton transfer in biological systems. Six potential mechanisms for reducing the dimethyl disulfide (DMDS) bridge through electron and proton capture were explored. Thermodynamic and kinetic analyses elucidated the sequence of proton and electron addition. MD-PMM, a method that combines molecular dynamics simulations and quantum-chemical calculations, was employed to compute the redox potential of the mechanism. This research provides valuable insights into the mechanisms and redox potentials involved in disulfide bridge reduction within proteins, offering an understanding of phenomena that are challenging to explore experimentally. All calculations used the Gaussian 09 software package at the MP2/6-311 + g(d,p) theory level. Visualization of the molecular orbitals and electron densities was conducted using Gaussview6. Molecular dynamics simulations were performed using GROMACS with the CHARMM36 force field. The PyMM program (Python Program for QM/MM Simulations Based on the Perturbed Matrix Method) is used to apply the Perturbed Matrix Method to MD simulations.

Unveiling [3 + 2] cycloaddition reactions of diphenyl diazomethane to thiobenzophenone and cycloaliphatic thioketones in the light of molecular electron density theory

The reactivity, regiochemistry and substituent effects observed in the [3 + 2] cycloaddition (32CA) reactions of diphenyldiazomethane (PDM) with thiobenzophenone and a series of cycloaliphatic thioketones (TKs) have been studied within the molecular electron density theory at the ωB97XD/6-311G(d,p) computational level. The cycloaliphatic TK series shows remarkable substituent effects, changing from a non-polar 32CA reaction to a highly polar one, with the electron density flowing from PDM to the corresponding TK in a reaction classified as a forward electron density flux (FEDF). These 32CA reactions follow a one-step mechanism through earlier asynchronous transition state structures in which the formation of the two new single bonds has not yet begun, and the energetically predicted regiochemistry towards the generation of 1,3,4-thiadiazole is in complete agreement with the experimental outcome.

Defect controlled spin state transitions in FePc adsorbed CrI3

Our study employs first principles to explore the impact of spin on iron phthalocyanine (molecule) upon adsorption onto defect-functionalized CrI3. We focus on three stable vacancy defects commonly found in CrI3, created by the removal of ‘-Cr-’, ‘-I-’ and ‘-CrI3-’ units from the pristine CrI3 lattice, analyzing their electronic and magnetic characteristics in both FM and AFM scenarios. Notably, these defects predominantly affect the electronic structure near the Fermi level. The adsorption of FePc, on defect-functionalized CrI3, exhibits reduced stability compared to the pristine substrate. FePc demonstrates two stable spin states, a 2 μB low spin state and a 4 μB high spin state. We present two spin-control mechanisms when FePc adsorbs onto these defect-functionalized substrates. We name these — substrate-induced and molecular spin vector-induced control. The former involves manipulating the magnetic order of the substrate (FM/AFM), leading to molecular spin state transitions. The latter mechanism involves modifying the spin orientation on the molecular Fe atom relative to the substrate’s spin (parallel/antiparallel), resulting in molecular spin state transitions. This research proposes novel effective methods to control the spin states of magnetic metal complexes during adsorption onto magnetic substrates, offering potential applications in molecular electronics and spintronics.

Exploring the neuroprotective role of artesunate in mouse models of anti-NMDAR encephalitis: insights from molecular mechanisms and transmission electron microscopy

BackgroundThe pathway involving PTEN-induced putative kinase 1 (PINK1) and PARKIN plays a crucial role in mitophagy, a process activated by artesunate (ART). We propose that patients with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis exhibit insufficient mitophagy, and ART enhances mitophagy via the PINK1/PARKIN pathway, thereby providing neuroprotection.MethodsAdult female mice aged 8–10 weeks were selected to create a passive transfer model of anti-NMDAR encephalitis. We conducted behavioral tests on these mice within a set timeframe. Techniques such as immunohistochemistry, immunofluorescence, and western blotting were employed to assess markers including PINK1, PARKIN, LC3B, p62, caspase3, and cleaved caspase3. The TUNEL assay was utilized to detect neuronal apoptosis, while transmission electron microscopy (TEM) was used to examine mitochondrial autophagosomes. Primary hippocampal neurons were cultured, treated, and then analyzed through immunofluorescence for mtDNA, mtROS, TMRM.ResultsIn comparison to the control group, mitophagy levels in the experimental group were not significantly altered, yet there was a notable increase in apoptotic neurons. Furthermore, markers indicative of mitochondrial leakage and damage were found to be elevated in the experimental group compared to the control group, but these markers showed improvement following ART treatment. ART was effective in activating the PINK1/PARKIN pathway, enhancing mitophagy, and diminishing neuronal apoptosis. Behavioral assessments revealed that ART ameliorated symptoms in mice with anti-NMDAR encephalitis in the passive transfer model (PTM). The knockdown of PINK1 led to a reduction in mitophagy levels, and subsequent ART intervention did not alleviate symptoms in the anti-NMDAR encephalitis PTM mice, indicating that ART’s therapeutic efficacy is mediated through the activation of the PINK1/PARKIN pathway.ConclusionsAt the onset of anti-NMDAR encephalitis, mitochondrial damage is observed; however, this damage is mitigated by the activation of mitophagy via the PINK1/PARKIN pathway. This regulatory feedback mechanism facilitates the removal of damaged mitochondria, prevents neuronal apoptosis, and consequently safeguards neural tissue. ART activates the PINK1/PARKIN pathway to enhance mitophagy, thereby exerting neuroprotective effects and may achieve therapeutic goals in treating anti-NMDAR encephalitis.

Formation of Organic Monolayers on KF-Etched Si Surfaces

Silicon is the most commonly used material in the microelectronics industry, due to its inherent advantages of high natural abundance, low cost, and high purity, coupled with the chemical and electrical stability at the interface with its oxide. For molecular electronics applications, oxide-free Si surfaces are widely used because of the relative ease of removing the oxide (SiOx) by chemical means, yielding a surface which forms strong covalent bonds with a wide range of chemical functional groups; another advantage is that these surfaces remain oxide-free in the absence of oxidising agents. Standard procedures require the use of either HF, NH4F, or a mixture of both as the etching solution; however, these two chemicals are highly corrosive and toxic, posing a significant risk to the experimentalist. Here, we report that for silicon wafers etched by using potassium fluoride, a less toxic chemical, the resulting surface is free of oxides and can be functionalized by self-assembled monolayers of 1,8-nonadiyne. To demonstrate this, Si/SiOx wafers were etched by using either KF or NH4F, followed by hydrosilylation with 1,8-nonadiyne and a click reaction of the terminal alkyne with azidomethylferrocene. The surface coverages and electron transfer kinetics of the ferrocene-terminated KF-etched surfaces are comparable to those formed by acidic fluoride etching procedures. This is the first study comparing the differences between surfaces functionalized by self-assembled monolayers of 1,8-nonadiyne which were etched by KF and NH4F. KF could be used as a replacement chemical for etching silicon wafers when a less corrosive and toxic chemical is required.