The present work provides insight into the effect of connectivity within isomeric 3,5-bis-(pyridin-2-yl)-phenyl (N^C^N) platinum and palladium complexes on their electron transmission properties within gold|molecule|gold junctions. The ligands 3,5-bis-(4-(methylthio)-pyridin-2-yl)-phenyl hexanoate (L m H) and 3,5-bis-(5-(methylthio)-pyridin-2-yl)-phenyl hexanoate (L p H) were synthesized and coordinated with either PtCl or PdCl to form complexes Pt m , Pt p , Pd m and Pd p . X-ray photoelectron spectroscopy (XPS) measurements evaluated the contacting modes of the molecules in the junctions. A combination of scanning tunneling microscopy-break junction (STM-BJ) measurements and density functional theory (DFT) calculations demonstrate that for the single-molecule S···S contacted junctions metal coordination enhanced the conductance compared with the free ligands. Notably, the higher degree of orbital mixing between the metal center and the ligand π-orbitals in the metal complexes plays a greater role than quantum interference to the extent that the complexes that incorporate ligands substituted with thiomethyl groups in meta positions relative to the pyridine-benzene linkages have a higher conductance than their para-analogs, e.g., Pt p -3.8 log-(G/G 0) and Pt m -3.3 log-(G/G 0), in contrast to the usual conductance trend (para > meta) for purely organic π-electron systems.

Achieving a comprehensive understanding and precise control of non-covalent interactions is crucial in molecular design and the development of functional molecular electronic devices, where supramolecular interactions enable the control of the local environment in molecular assemblies. Here, intermolecular interactions are used to create a complex supramolecular assembly by pi stacking of 1,1 '-bis(4-(methylthio)-phenyl)-[4,4 '-bipyridine]-1,1 '-diium chloride (1[Cl]2) and tetracyanoquinodimethane radical anion (TCNQ-), whose crystal structure is determined by an electron diffraction technique, showing the presence of stacked 12+- 2(TCNQ-) units. This solid dissolves in aqueous solutions of cucurbit[8]uril (CB[8]), which acts as the host, to form a supramolecular five-molecule {12+-2(TCNQ-)@2CB[8]} assembly. Its transport properties result in a significant enhancement of conductance. Theoretical studies confirm the stability of the supramolecular assembly and corroborate the enhancement in conductance. These results present a simple and effective method for stabilizing and enhancing charge transport efficiency through a combination of non-covalent and supramolecular interactions, with significant implications for the development of future (opto)electronic devices.

Large-area molecular junctions offer a promising pathway toward the scalable implementation of molecular electronic devices, where charge transport is strongly governed by molecular structure and supramolecular organization. In this work, two diketopyrrolopyrrole (DPP) derivatives featuring tailored alkyl chain lengths designed to isolate the DPP moiety from the anchor groups, are used to form well-ordered Langmuir-Blodgett (LB) films. By bridging the gap between single-molecule behavior and collective transport in large-area devices, molecular junctions were first characterized using the 'scanning tunneling microscopy (STM) touch-to-contact' method. These junctions exhibit higher conductance than conventional single molecule I(s) measurements, attributed to intermolecular charge-transfer processes enabled by the ordered LB assemblies. Consistent with this enhanced conductance, low transition voltages (Vtrans) indicate favorable alignment between the metal electrode Fermi level and the frontier molecular orbitals. To assess device-relevant performance, large-area molecular junctions were fabricated using Eutectic Gallium-Indium (EGaIn) alloy as a soft top electrode. These junctions exhibit high yield and reproducibility, confirming the formation of robust and high-quality junctions that mirror the transport behavior observed at the single-molecule scale. Together, these results establish a consistent transport picture across both small- and large-area junctions identifying the DPP moiety as a highly effective molecular wire. This effectiveness stems from the capability of these DPP derivatives to form well-ordered films exhibiting intermolecular charge-transfer processes, which, combined with a favorable energy-level alignment with the electrodes, ultimately results in high device conductance.

Spin-coated films based on silver butyrate precursor solutions are submitted to focused Ga+ irradiation for the direct fabrication of Ag-enriched nanostructures. We report that, through the optimization of the solutions' concentration, the spin-coating conditions, and the irradiation parameters, Ag-enriched patterned films with a tunable microstructure are obtained. In the case of a microstructure consisting of large and continuous Ag-enriched platelets, the patterned film is metallic, with resistivity down to 90 µΩ·cm. In the case of a microstructure consisting of small and discontinuous Ag-enriched nanoparticles, the corresponding patterned film is found to be suitable as a Surface-Enhanced Raman Spectroscopy (SERS) substrate. As proof of concept, the SERS signals produced by thiophenol solutions are measured and compared to a rough Ag film grown by sputtering, leading to a 200 times higher signal. Given the low Ga+ irradiation fluence required to produce tunable Ag nanostructures with metallic or SERS functionality, the obtained results highlight the potential of silver butyrate precursor solutions for the high-throughput printing of a nanomaterial with applications in nanoelectronics (metallic interconnects) and nanophotonics (SERS substrates).

Dynamic, raft-like nanodomains are considered key regulators of membrane architecture and function, playing crucial roles in cell signaling, membrane trafficking, and protein localization. However, the mechanisms underlying their formation and stabilization remain poorly understood. In this contribution, we investigate raft-like nanodomains in pseudobinary supported lipid membranes (SLMs) composed of 1,2-dipalmitoyl-sn-glycero-3phosphocholine (DPPC) and cholesterol (CHOL) in a 1:1 ratio, and a synthetic glucosylceramide (GSL1). By integrating interfacial thermodynamic analysis of pseudobinary (DPPC:CHOL 1:1 + GSL1) Langmuir films with atomic force microscopy (AFM) of Langmuir-Blodgett films, we uncover a dual behavior of GSL1: it exhibits strong attractive interactions and efficient packing with CHOL, but poor miscibility with DPPC. This leads to preferential segregation of GSL1 away from DPPC and its incorporation into CHOL-rich domains, which are interpreted here as GSL1-enriched lipid raft-like nanodomains. These findings are corroborated by AFM topographical analysis. Beyond advancing our understanding of glycosphingolipid-cholesterol interactions, this work offers a versatile framework for engineering complex SLMs that more faithfully replicate the structural and functional complexity of biological membranes, with potential applications in fundamental membrane research and drug delivery systems.

The growth of functional materials at precise locations using focused electron irradiation has recently attracted considerable attention, including techniques such as Focused Electron Beam Induced Deposition (FEBID), growth by decomposition of spin-coated organometallic films, ice lithography, and others. Ice lithography requires lowering the substrate temperature, which can be achieved by means of a cryogenic module or a Peltier accessory. The same approach is applied to FEBID growth under cryogenic conditions (Cryo-FEBID) and to the related technique Cryo-FIBID, where ions constitute the irradiating charge instead of electrons. These techniques outperform their corresponding room-temperature processes due to their higher speed. In this manuscript, we present the optimization of cobalt-based deposit growth using Cryo-FEBID. For the first time, a conductive material grown using Cryo-FEBID is demonstrated, opening the possibility of applying this technique to create nanoscale electrical contacts. These cobalt-based Cryo-FEBID deposits are used to fabricate the top-contact electrode in vertical, large-area molecular electronic devices, achieving state-of-the-art yield and performance. Importantly, this nanofabrication method offers unique advantages, including direct-writing with precise control over substrate location, size, shape and thickness, paving the way for the integration of molecular-scale functionalities into conventional microelectronic platforms.

The present work provides insight into how the conformations of flexible molecules can impact their single-molecule conductance. Six thiol-substituted carbazole-based molecules are synthesized and characterized. In four, two carbazole groups are joined by a linking group (1,3-propane or meta-xylene) while the remaining two are model monocarbazoles. Using a combination of X-ray photoelectron spectroscopy (XPS), single-molecule conductance measurements, and density functional theory (DFT) calculations, we demonstrate that upon transitioning from a self-assembled monolayer (SAM) to a single-molecule junction, the intermolecular interactions give way to intramolecular interactions. This resulted in the flexible bicarbazole molecular wire switching conductance mechanisms, which occurred primarily via the covalent conjugated aromatic part of the molecule in the SAM to one including conductance via noncovalent π-π interactions in the single-molecule junction.

The electrical characteristics of a molecular junction are highly sensitive to the nature and uniformity of the molecule|electrode contacts. This gives rise to significant interest in the development of not only the active molecular structures that modulate charge transport and the anchor groups that contact them to the electrodes, but also methods for assembling uniform molecular monolayers on a substrate electrode and subsequent fabrication of a "top electrode" to achieve the reliable fabrication of viable molecular electronic devices. In this contribution, 4-(4-(4-(trimethylsilylethynyl)-phenylethynyl)-phenylethynyl)-aniline was converted to the corresponding diazonium salt and electrografted onto highly oriented pyrolytic graphite (HOPG), resulting in an organized monolayer covalently bonded to the HOPG "substrate" electrode. Subsequently, focused electron-beam-induced deposition was used to form an amorphous carbon top electrode (C-FEBID) onto the monolayer from a naphthalene precursor. By guiding the raster scanning of the electron beam, the position, shape, and thickness of the carbon electrode "written" onto the monolayer can be controlled with nanometer precision. In addition, as a proof-of-principle demonstration of the construction of the interconnects necessary for integration of molecular devices, platinum was deposited precisely on top of the C-FEBID electrodes, using focused-ion-beam-induced deposition of PtMe3CpMe (CpMe = η5-C5H4Me) (Pt-FIBID). The HOPG|molecule|C-FEBID|Pt-FIBID "large area" junctions produced in this manner exhibited excellent reproducibility and were free of short circuits for top-electrode dimensions ranging from 4 × 4 to 8 × 8 μm2. The electrical characteristics of these devices were measured and modeled by using quantum chemical approaches. These results illustrate alternative routes toward the fabrication of planar 2D devices based on molecular monolayers and carbon electrodes.

Focused ion beam (FIB) is a nanopatterning technique commonly used for material removal, but in combination with a precursor material it gives rise to additive nanomanufacturing, of great interest in nanotechnology and semiconductor applications. The precursor material can be delivered onto the substrate either in the gas form, through a gas-injection system, or in thin-film form, through spin coating. Recently, it has been found that the electrical resistance of spin-coated PdAc organometallic films submitted to FIB irradiation can be metallic at an optimized ion dose, without the need of any post-processing purification step. On the other hand, if such PdAc films are submitted to low-dose focused electron beam irradiation (FEB), they become an insulating material. Here, we combine the use of FIB and FEB irradiation to produce (additively) micro- and nano-structured materials that act as gates in electronic devices. Three different gate configurations have been explored, and applied to suppress superconductivity in metallic nanowires through electric-field effects, including lateral and top gating. This new fabrication technique for investigation of electrical gating effects at the micro- and nano-scales stands out by its precision and resolution (due to the use of focused charged beams), by the absence of sacrificial resist layers, and by the process speed.

A direct nanowriting procedure using helium- and neon-focused ion beams and spin-coated organometallic thin films is introduced and applied to the fabrication of Pd-enriched metallic structures in a single lithography step. This process presents significant advantages over multi-step resist-based lithography and focused beam-induced deposition using gaseous precursors, such as its simplicity and speed, respectively. The optimized process leads to Pd-rich structures with low electrical resistivity values of 141 and 152 mu Omega cm under Ne+ or He+ fluences of 1000 and 5000 mu C cm-2, respectively. These resistivity values correlate well with compositional and microstructural studies, indicating a high Pd metallic content in a dense structure with a few-nm grain size. The obtained results are compared to similar structures fabricated by direct electron and gallium beam nanowriting, demonstrating the full potential of nanopatterned Pd-based organometallic thin films under the most common focused charged beams. The practical applications of combining spin-coated organometallic thin films with focused beam nanowriting in micro- and nano-lithography modern procedures are also discussed in this contribution.

Cell membranes are crucial elements in living organisms, serving as protective barriers and providing structural support for cells. They regulate numerous exchange and communication processes between cells and their environment, including interactions with other cells, tissues, ions, xenobiotics, and drugs. However, the complexity and heterogeneity of cell membranes—comprising two asymmetric layers with varying compositions across different cell types and states (e.g., healthy vs. diseased)—along with the challenges of manipulating real cell membranes represent significant obstacles for in vivo studies. To address these challenges, researchers have developed various methodologies to create model cell membranes or membrane fragments, including mono- or bilayers organized in planar systems. These models facilitate fundamental studies on membrane component interactions as well as the interactions of membrane components with external agents, such as drugs, nanoparticles (NPs), or biomarkers. The applications of model cell membranes have extended beyond basic research, encompassing areas such as biosensing and nanoparticle camouflage to evade immune detection. In this review, we highlight advancements in the engineering of planar model cell membranes, focusing on the nanoarchitectonic tools used for their fabrication. We also discuss approaches for incorporating challenging materials, such as proteins and enzymes, into these models. Finally, we present our view on future perspectives in the field of planar model cell membranes.

Metal adatoms do not split, nor replace, the hydrogens at the coordination nodes of pyrazole derivates when forming metallophilic complexes on surfaces. The porous structures are driven by kinetics into divergent substrate dependent arrangements.

The present work provides insight into the effect of connectivity within isomeric 1,2-bis(2-pyridylethynyl)benzene (bpb) palladium complexes on their electron transmission properties within gold|single-molecule|gold junctions. The ligands 2,2 '-((4,5-bis(hexyloxy)-1,2-phenylene)bis(ethyne-2,1-diyl))bis(4-(methylthio)pyridine) (Lm ) and 6,6 '-((4,5-bis(hexyloxy)-1,2-phenylene)bis(ethyne-2,1-diyl))bis(3-(methylthio)pyridine) (Lp ) were synthesized and coordinated with PdCl2 to give the trans-Pd(Lm or p )Cl2 complexes. X-ray photoelectron spectroscopy (XPS) measurements shed light on the contacting modes of the molecules in the junctions. A combination of scanning tunneling microscopy-break junction (STM-BJ) measurements and density functional theory (DFT) calculations demonstrate that the typical lower conductance of meta- compared with para-connected isomers in a molecular junction was suppressed upon metal coordination. Simultaneously there was a modest increase in both conductance and Seebeck coefficient due to the contraction of the HOMO-LUMO gap upon metal coordination. It is shown that the low Seebeck coefficient is primarily a consequence of how the resonances shift relative to the Fermi energy.

Thermoelectric materials have garnered significant interest for their potential to efficiently convert waste heat into electrical energy at room temperature without moving parts or harmful emissions. This study investigated the impact of the HOMO-LUMO (H-L) gap on the thermoelectric properties of three distinct classes of organic compounds: conjugated aromatics (isoindigos (IIGs)), quinoidal molecules (benzodipyrrolidones (BDPs)), and donor-acceptor systems (bis(pyrrol-2-yl)squaraines (BPSs)). These compounds were chosen for their structural simplicity and linear pi-conjugated conductance paths, which promote high electrical conductance and minimize complications from quantum interference. Single-molecule thermoelectric measurements revealed that despite their low H-L gaps, the Seebeck coefficients of these compounds remain low. The alignment of the frontier orbitals relative to the Fermi energy was found to play a crucial role in determining the Seebeck coefficients, as exemplified by the BDP compounds. Theoretical calculations support these findings and suggest that anchor group selection could further enhance the thermoelectric behavior of these types of molecules.

Ginger is a culinary spice with a millennia-old tradition due to its extensive therapeutic applications, recently validated by scientific studies. In particular [6]-Gingerol, a key active molecule in ginger, exhibits extraordinary capabilities in addressing a wide spectrum of health issues. However, its therapeutic potential is limited by its rather low bioavailability. The incorporation of [6]-Gingerol into membrane systems of liposomes, micelles, or exosomes is a promising strategy to overcome this limitation. In this contribution, we report the hitherto unexplored surface properties of [6]-Gingerol at the air-water interface. Our comprehensive study, which includes a detailed analysis of surface pressure and surface potential vs. area per molecule isotherms, surface compression modulus, and Brewster Angle Microscopy, demonstrates the capability of [6]-Gingerol to form Langmuir films. These films can be transferred onto solid substrates, forming remarkably homogeneous Langmuir-Blodgett films which have been characterized by Quartz Crystal Microbalance and Atomic Force Microscopy. This study may be of interest as it paves the way for future research on introducing [6]-Gingerol into membrane systems and transporting it into living cells.

AbstractAttaining precise control over molecular arrangements is of paramount importance for numerous applications in nanotechnology, particularly in constructing molecular templates to accurately immobilize target materials on surfaces. A strategic combination of supramolecular and interfacial chemistry may serve to build a well‐organized molecular network, enabling the subsequent location of target molecules on specific positions of a surface. A supramolecular complex (compound 1) comprised of a melamine unit forming hydrogen bonds with dendritic arms terminated in a coumarin unit is utilized, which readily undergoes photodimerization. The research demonstrates the formation of well‐organized Langmuir films of compound 1 which can be transferred on substrates at low surface pressures adopting a lying‐flat orientation. Upon irradiation of the pristine films at 365 nm the coumarin units undergo photo‐cross linking, leading to the formation of a compact photo‐crosslinked film. Incubation of these photo‐crosslinked films in a solution containing 1‐hexanethiol results in the withdrawal of the melamine and the chemisorption of two thiol molecules per each melamine unit. The nanopores created by the removal of the melamine core are attributed to the disruption of hydrogen bonds in compound 1 by the thiols. This precisely defined molecular network holds significant promise as a template for orchestrating the arrangement of functional materials on surfaces.

The investigation of precursor classes for the fabrication of nanostructures is of specific interest for maskless fabrication and direct nanoprinting. In this study, the differences in material composition depending on the employed process are illustrated for focused-ion-beam- and focused-electron-beam-induced deposition (FIBID/FEBID) and compared to the thermal decomposition in chemical vapor deposition (CVD). This article reports on specific differences in the deposit composition and microstructure when the (H3Si)2Fe(CO)4 precursor is converted into an inorganic material. Maximum metal/metalloid contents of up to 90 at. % are obtained in FIBID deposits and higher than 90 at. % in CVD films, while FEBID with the same precursor provides material containing less than 45 at. % total metal/metalloid content. Moreover, the Fe:Si ratio is retained well in FEBID and CVD processes, but FIBID using Ga+ ions liberates more than 50% of the initial Si provided by the precursor. This suggests that precursors for FIBID processes targeting binary materials should include multiple bonding such as bridging positions for nonmetals. In addition, an in situ method for investigations of supporting thermal effects of precursor fragmentation during the direct-writing processes is presented, and the applicability of the precursor for nanoscale 3D FEBID writing is demonstrated.

Towards transparent and flexible large area molecular electronic devices.

Abstract Future applications of single‐molecular and large‐surface area molecular devices require a thorough understanding and control of molecular junctions, interfacial phenomena, and intermolecular interactions. In this contribution the concept of single‐molecule junction and host‐guest complexation to sheath a benchmark molecular wire–namely 4,4′‐(1,4‐phenylenebis(ethyne‐2,1‐diyl))dianiline – with an insulating cage, pillar[5]arene 1,4‐diethoxy‐2‐ethyl‐5‐methylbenzene is presented. The insertion of one guest molecular wire into one host pillar[5]arene is probed by 1H‐NMR (nuclear magnetic resonance), whilst the self‐assembly capabilities of the amine‐terminated molecular wire remain intact after complexation as demonstrated by XPS (X‐ray photoelectron spectroscopy) and AFM (atomic force microscopy). Encapsulation of the molecular wire prevents the formation of π‐ π stacked dimers and permits the determination of the true single molecule conductance with increased accuracy and confidence, as demonstrated here by using the STM–BJ technique (scanning tunneling microscopy– break junction). This strategy opens new avenues in the control of single‐molecule properties and demonstrates the pillararenes capabilities for the future construction of arrays of encapsulated single‐molecule functional units in large‐surface area devices.