Molecular Confinement Research Articles

Vertically Expanded Crystalline Porous Covalent Organic Frameworks.

Covalent organic frameworks (COFs) can be developed for molecular confinement and separation. However, their proximate π stacks limit the interlayer distance to be only 3-6 Å, which is too small for guests to enter. As a result, COFs block access to the x-y space and limit guest entry/exit strictly to only the pores along the z direction. Therefore, the extended faces of each layer are hidden between layers, precluding any interactions with guest molecules. Here, we report a strategy for opening interlayer spaces of COFs to attain newly accessible nanospaces between layers. This becomes possible using coordination bonds to replace the conventional π-π stacks between layers. We demonstrate this concept by synthesizing two-dimensional covalent cobalt(II) porphyrin layers through topology-guided polymerization, which were piled up by bidentate axial pillars through coordination bonds with cobalt(II) porphyrin along the z direction, assembling vertically expanded COFs via a one-pot reaction. The resultant frameworks separate the layers with axial pillars and create discrete apertures between layers defined by the molecular length of the pillars. Consequently, the originally inaccessible interlayers are open for guest access, while the polygonal π planes are exposed to trigger various supramolecular interactions. Vapor sorption, breakthrough experiments, and computational studies mutually revealed that the vertically expanded frameworks with optimal interlayer slits induce additional interactions to discriminate benzene and cyclohexane and separate their mixtures efficiently under ambient conditions.

Molecular Confinement Engineering Induced Super Thermostable and RT‐Adjustable Gel for Tri‐Heat‐Channeled Smart Window

AbstractThermochromic hydrogel‐based smart windows hold great potential for building energy‐saving. However, most of thermochromic hydrogels possess high response temperatures (RT) and poor size stability under heat, resulting in limited energy‐saving performance for smart windows. Here, a printable thermochromic gel (PNC) is reported with low thermal shrinkage and tunable RT for smart windows applications via molecular confinement engineering. The RT of PNC gel is well within the comfort temperature zone of the human body and can be modulated (26.5–31.5 °C) by the introduced support networks. Importantly, the resultant gel exhibits a super transmittance (95%) in visible light and an outstanding modulation (87%) for sunlight. Based on PNC gel, a tri‐heat‐channeled smart window is fabricated using a multilevel thermal regulation strategy that couples conduction, radiation, and evaporative cooling. The tri‐heat‐channeled smart window demonstrates outstanding daytime cooling (10 °C lower than conventional windows) and can cut off 30% of annual heating, ventilation, and air‐conditioning (HAVC) energy consumption. Furthermore, a novel smart window is designed with invisible shutters that appear only when needed. This work offers novel clues for constructing versatile gels and innovative smart windows for building energy‐saving.

Ultrathin Self-Healing Nanofibrous Membrane with a Hierarchical Confined Structure for Biomimetic Epidermal Electrodes.

Integrating self-healing capabilities into epidermal electrodes is crucial to improving their reliability and longevity. Self-healing nanofibrous materials are considered an ideal candidate for constructing ultrathin, long-lasting wearable epidermal electrodes due to their lightweight and high breathability. However, due to the strong interaction between fibers, self-healing nanofiber membranes cannot exist stably. Therefore, the development of self-healing and breathable nanofibrous epidermal electrodes still remains a major challenge. Here, a hierarchical confinement strategy that combines molecular and spatial confinement to overcome supramolecular hydrogen bonding between self-healing nanofibers is reported, and an ultrathin self-healing nanofibrous epidermal electrode with a neural net-like structure is developed. It can achieve real-time monitoring of electrophysiological signals through long-term conformal attachment to skin or plants and has no adverse effects on skin health or plant growth. Given the almost imperceptible nature of epidermal electrodes to users and plants, it lays the foundation for the development of biocompatible, self-healing, wearable, flexible electronics.

Synthesis of nitrogen-rich porous carbon via a molecular confinement strategy for activating peroxymonosulfate in bisphenol A degradation: Role of singlet oxygen and electron transfer process

Nitrogen-doped porous carbon (NPC) catalysts show potential for activating peroxymonosulfate (PMS) to treat water pollution. However, nitrogen (N) experiences significant loss during pyrolysis, posing challenges for synthesizing N-rich carbon catalysts. This study innovatively proposed a molecular confinement strategy using the C−S−C bond formed between graphitic carbon nitride and mercaptan. Under this confinement, we successfully synthesized NPC-15 with a high N content (21.4 at%), surpassing most catalysts reported in the literature. NPC-15/PMS system showed excellent performance in degrading bisphenol A (BPA), achieving complete degradation within 3 min (kobs = 1.771 min−1), surpassing the effectiveness of most previously reported catalysts. The NPC-15/PMS system exhibited excellent performance and stability under various conditions, reducing BPA toxicity to ecological and human embryonic kidney cells. Moreover, it maintained stability during long-term continuous operation in a fixed-bed reactor, showing promise for practical applications. Through experiments and theoretical calculations, the mechanism of NPC-15 activating PMS was comprehensively investigated. The NPC/PMS system operated via a dual non-radical pathway involving singlet oxygen and electron transfer process induced by pyridinic N and graphitic N dual active sites. Pyridinic N promoted the generation of 1O2, while graphitic N supported the electron transfer process. This study introduced a new strategy for the preparation of N-rich carbon catalysts and proposed a novel method for the removal of emerging pollutants in water.

Fluorescent carbon dots for sensing applications: a review.

Luminescent carbon dots (CDs) are important class of nanomaterials with fantastic photoluminescence (PL) properties, great biocompatibility, extraordinary solubility in water, minimal expense, and so on. There are many methods for their preparation and they are mainly classed into two groups, top-down and bottom-up approaches. In order to understand the origin of fluorescence in quantum CDs, three mechanisms have been proposed namely molecular state, surface state, and quantum confinement phenomenon. Fluorescent CDs have significant application in the fields of biochemical sensing, photocatalysis, bioimaging, delivery of drugs, and other related fields. In this review article the application of quantum dots as detecting component, for the sensing of different targets, has been summed up. In fact, the detection of several analytes including, anions, cations, small molecules, polymers, cells, and microscopic organisms has been discoursed. Moreover, the future aspects of CDs as detecting resources have been explored.

Polymethylene trisulfide/reduced graphene oxide nanocomposite electrodes: Deciphering microstructure/electrochemistry relationship

Flexible polysulfide electrodes can play a crucial role in the future development of wearable energy storage devices. Understanding the electrochemical energy storage mechanism in these electrodes can guide the engineering of polysulfides and their composites to design high-performance flexible energy storage devices. Polymethylene trisulfide (PMTS) and PMTS/reduced graphene oxide (rGO) nanocomposites, synthesized via in-situ interfacial polymerization, are introduced as active materials for developing high-performance electrodes. The fundamental scientific objective of this study is to uncover the correlation between the microstructural properties of linear polysulfides and the electrochemical behavior of low molecular weight intermediate polysulfide species. Based on microstructural studies, Coulomb interactions between rGO and PMTS macromolecules dictate PMTS chain confinements. Such molecular confinements affect the glass transition temperature and the crystallinity of PMTS, hence controlling the electrochemistry of electrodes. A high specific capacity of 366 mAh/g (5 μA) is reached using the flexible PMTS/0.5 wt% rGO nanocomposite electrode in Li-PMTS cells. The suggested mechanism for the anodic and cathodic polarizations in Li-PMTS cells is based on the formation of low molecular weight sulfide polymeric species. Therefore, the crystallinity and moveability of polymeric chains are introduced as structural features of polysulfide electrodes that can be utilized to improve the performance of energy storage systems based on these active materials.

Ab initio informed machine learning potential for tribochemistry and mechanochemistry: Application for eco–friendly gallate lubricant additive

Mechanochemistry and tribochemistry processes involve multiple physical/chemical interactions induced by extreme conditions including molecular confinement, high temperatures and mechanical stress applied. Simulating these processes by molecular dynamics is very challenging. While force fields fall short reproducing the enhanced reactivity arising by quantum effects, ab initio molecular dynamics is severely limited by the complexity of the systems of interest, their sizes, and the long-time scale on which relevant events take place. In this work using an active learning approach, a landmark deep neural network potential has been developed which reproduces the accuracy of ab initio interactions at the classical molecular dynamics computational cost and permits to successfully simulate the tribochemical processes occurring at the interface between butyl gallate molecules and iron substrates under tribological conditions. The simulations of the dynamics of the Fe-gallate system when sliding under an imposed external load reveal the key atomistic mechanisms underlying the formation of the friction reducing lubricant tribofilm and permit to characterize the tribological properties of the explored systems, clearly exposing the shortcoming of reactive force field based approaches. The successful development of neural network potentials, making it possible to push the limits of molecular dynamics marrying accuracy with system sizes and long time scales, paves the route toward a new area in computational tribochemistry.

Optimizing particle morphology: Atomic iron–nitrogen centers with graphitic‐N for highly efficient CO2 electroreduction

AbstractTransition metal‐coordinated nitrogen sites on carbon catalysts (M‐N‐C) hold potential for CO2 electroreduction (CO2ER), but optimal morphology and active sites are unclear. We introduce a novel approach, developing zeolitic imidazolate framework‐8 (ZIF‐8)‐derived carbon catalysts with Fe‐N and graphitic‐N sites (Fe2‐NC) via molecular confinement and thermal activation. Fine‐tuning ZIF‐8 size and activation temperature yielded 44.98% active N sites. The 300 nm Fe2‐NC catalyst displayed outstanding CO2‐to‐CO conversion, with a 170 mV overpotential and 94.3% Faradaic efficiency at −0.5 V, outperforming state‐of‐the‐art materials. Enhanced CO2ER kinetics and conductivity contributed to this superiority. Results highlight the correlation between maximum CO Faradaic efficiency and cumulative Fe‐N/graphitic‐N sites, dependent on size and activation. The 300 nm Fe2‐NC in a gas diffusion electrode‐loaded flow cell achieved a 15.3‐fold CO partial current density increase. In a Zn‐CO2 battery, the 300 nm Fe2‐NC demonstrated a peak power density of 0.618 mW cm−2, showcasing energy storage potential.

Density and confinement effects on fluid velocity slip

Understanding the velocity slip of fluids in channels of molecular length scales is essential for accurately manipulating their flow in engineering applications, such as in water desalination or, by reversing the process, osmotic power generation. This study addresses two major open questions, namely (a) the range of validity of the Navier-Stokes equations with slip boundary conditions in describing fluid flows within channels of molecular confinement, and (b) the effect of fluid density and confinement as well as surface properties, such as microscopic roughness and curvature, on fluid slippage along walls. Using a hard-sphere fluid model and describing the fluid-wall interactions by the Maxwell scattering kernel, an event-driven molecular dynamics simulation study was performed in planar and cylindrical channels of different sizes and accommodation coefficients with varying fluid densities. The results show that the well-known criterion for the slip solution, which is valid in rarefied conditions, also holds for a dense gas, i.e., the predictive accuracy improves with decreasing Knudsen numbers, as long as the channel size is larger than about ten molecular diameters. We also find that the key quantity influencing the friction coefficient of a fluid is the peak density at the walls, rather than the nominal density, the fluid confinement, or the channel curvature, as found in previous studies. In particular, higher nominal densities lead to higher density peaks, and therefore a decrease in slip, while tighter confinements lead to lower density peaks, and therefore an increase in slip, regardless of channel geometry. Furthermore, the velocity slip depends on the microscopic roughness via the Smoluchowski factor. These findings are a stepping stone towards a deeper understanding of the molecular mechanisms underlying fluid velocity slip in molecular-scale channels. Published by the American Physical Society 2024

Confinement effect of inter-arm interactions on glass formation in star polymer melts.

We utilized molecular dynamic simulation to investigate the glass formation of star polymer melts in which the topological complexity is varied by altering the number of star arms (f). Emphasis was placed on how the "confinement effect" of repulsive inter-arm interactions within star polymers influences the thermodynamics and dynamics of star polymer melts. All the characteristic temperatures of glass formation were found to progressively increase with increasing f, but unexpectedly the fragility parameter KVFT was found to decrease with increasing f. As previously observed, stars having more than 5 or 6 arms adopt an average particle-like structure that is more contracted relative to the linear polymer size having the same mass and exhibit a strong tendency for intermolecular and intramolecular segregation. We systematically analyzed how varying f alters collective particle motion, dynamic heterogeneity, the decoupling exponent ζ phenomenologically linking the slow β- and α-relaxation times, and the thermodynamic scaling index γt. Consistent with our hypothesis that the segmental dynamics of many-arm star melts and thin supported polymer films should exhibit similar trends arising from the common feature of high local segmental confinement, we found that ζ increases considerably with increasing f, as found in supported polymer films with decreasing thickness. Furthermore, increasing f led to greatly enhanced elastic heterogeneity, and this phenomenon correlates strongly with changes in ζ and γt. Our observations should be helpful in building a more rational theoretical framework for understanding how molecular topology and geometrical confinement influence the dynamics of glass-forming materials more broadly.

Molecularly Confined Topochemical Transformation of MXene Enables Ultrathin Amorphous Metal-Oxide Nanosheets.

Two-dimensional (2D) amorphous nanosheets with ultrathin thicknesses have properties that differ from their crystalline counterparts. However, conventional methods for growing 2D materials often produce either crystalline flakes or amorphous nanosheets with an uncontrollable thickness. Here, we report that ultrathin amorphous metal-oxide nanosheets featuring superior flatness can be realized through the molecularly confined topochemical transformation of MXene. Using MXene Ti2CTx as an example, we show that surface modification of Ti2CTx nanosheets with molecular ligands, such as oleylamine (OAm) and oleic acid (OA), not only imparts notable colloidal dispersity to Ti2CTx nanosheets in nonpolar organic solvents but also confines their subsequent oxidation to in-plane configurations. We demonstrate that unlike the drastic oxidation conventionally observed for pristine MXene, hydrophobizing MXene with OAm and OA ligands enables individual Ti2CTx nanosheets to undergo independent oxidation in a nondestructive manner, resulting in amorphous titanium oxide (am-TiO2) nanosheets that faithfully retain the dimension and flatness of pristine MXene. These am-TiO2 nanosheets exhibit exceptional activity as substrates for surface-enhanced Raman scattering. Importantly, this molecular confinement strategy can be extended to other MXene materials, providing a versatile approach for synthesizing ultrathin amorphous metal-oxide nanosheets with tailored compositions and functionalities.

Molecular Engineering and Confinement Effect Powered Ultrabright Nanoparticles for Improving Sensitivity of Lateral Flow Immunoassay.

The application of traditional lateral flow immunoassay (LFIA)-based gold nanoparticles (AuNPs) to measure traces of target chemicals is usually challenging. In this study, we developed an integrated strategy based on molecular engineering and the spatial confinement of nanoparticles (NPs) to obtain ultrahigh quantum yields (QYs) of aggregation-induced emission (AIE) fluorescence NPs and employed them for the highly sensitive detection of T-2 toxin on the LFIA platform. Tetraethyl-4,4',4″,4‴-(ethene-1,1,2,2-tetrayl)tetrabenzoate (TCPEME), an AIE luminogen, was designed using molecular engineering to lower the energy gap, achieving higher QYs (26.26%) than previous AIEgens (13.02%). Subsequently, TCPEME-doped fluorescence NPs (TFNPs) achieved ultrahigh QYs, up to 84.55%, which were generated from the strong restriction of the NP state, efficiently suppressing nonradiative relaxation channels verified by ultrafast electron dynamics. On the LFIA platform, the sensitivity of the designed TFNP-based LFIA (TFNP-LFIA) was 10.4-fold and 4.3-fold more sensitive than that of the AuNP-LFIA and TPENP-LFIA for detecting the T-2 toxin, respectively. In addition, TFNP-LFIA was used for detecting T-2 toxin in samples and showed satisfactory recoveries (79.5 to 122.0%) with CV (1.49 to 11.75%), which implied excellent application potential for TFNP-LFIA. Overall, dual improvement of the molecule in fluorescence performance originating from the molecular engineering and spatial confinement of NPs could be an efficient tool for promoting the development of high-performance reporters in LFIA.

Collective Effects of Multiple Fluorine Atoms Causing π-philic Characteristic within a Caged Polyoxometalate Framework.

Perfluorination brings about distinctive properties arising from the unusual nature of the F element, which have been extensively developed in materials science and chemistry. Herein we report that the construction of F-rich inner space within a hollowed Mo132 O372 cage ([Mo132 O372 (OCOR)30 (H2 O)72 ]42- ) leads to the emergence of unique guest binding activities in encapsulation. Prominently, the trifluoroacetate-modified cage (R=CF3 , 2) having as many as 90 F groups inside favors trapping cyclopentadiene (Cp), which is hardly trapped by the non-fluorinated counterpart (R=CH3 , 1). Systematic studies using related hydrocarbons show that the amount of the encapsulated guest is correlated with the unsaturation degree of the guests, implying the involvement of the attractive interaction of the CF3 -modified interior wall with the guest π-electron clouds. Control experiments using the semi-fluorinated analogues (R=CF2 H, CFH2 ) reveal that the perfluorination is a critical factor to facilitate the Cp encapsulation by 2, indicating that collective effects of polar C-F bonds spreading over the interior surface, rather than the polarity of the individual C-F bonds, are responsible. We also provide a successful example of the physical molecular confinement within the cage through the "ship-in-a-bottle" Diels-Alder reaction between trapped diene and dienophile.

Rapid plasma membrane isolation via intracellular polymerization-mediated biomolecular confinement

Plasma membrane isolation is a foundational process in membrane proteomic research, cellular vesicle studies, and biomimetic nanocarrier development, yet separation processes for this outermost layer are cumbersome and susceptible to impurities and low yield. Herein, we demonstrate that cellular cytosol can be chemically polymerized for decoupling and isolation of plasma membrane within minutes. A rapid, non-disruptive in situ polymerization technique is developed with cell membrane-permeable polyethyleneglycol-diacrylate (PEG-DA) and a blue-light-sensitive photoinitiator, lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP). The photopolymerization chemistry allows for precise control of intracellular polymerization and tunable confinement of cytosolic molecules. Upon cytosol solidification, plasma membrane proteins and vesicles are rapidly derived and purified as nucleic acids and intracellular proteins as small as 15 kDa are stably entrapped for removal. The polymerization chemistry and membrane derivation technique are broadly applicable to primary and fragile cell types, enabling facile membrane vesicle extraction from shorted-lived neutrophils and human primary CD8 T cells. The study demonstrates tunable intracellular polymerization via optimized live cell chemistry, offers a robust membrane isolation methodology with broad biomedical utility, and reveals insights on molecular crowding and confinement in polymerized cells. Statement of significanceIsolating the minute fraction of plasma membrane proteins and vesicles requires extended density gradient ultracentrifugation processes, which are susceptible to low yield and impurities. The present work demonstrates that the membrane isolation process can be vastly accelerated via a rapid, non-disruptive intracellular polymerization approach that decouples cellular cytosols from the plasma membrane. Following intracellular polymerization, high-yield plasma membrane proteins and vesicles can be derived from lysis buffer and sonication treatment, respectively. And the intracellular content entrapped within the polymerized hydrogel is readily removed within minutes. The technique has broad utility in membrane proteomic research, cellular vesicle studies, and biomimetic materials development, and the work offers insights on intracellular hydrogel-mediated molecular confinement.

Insights into the Mechanism of Tryptophan Fluorescence Quenching due to Synthetic Crowding Agents: A Combined Experimental and Computational Study.

Intrinsic tryptophan fluorescence spectroscopy is an important tool for examining the effects of molecular crowding and confinement on the structure, dynamics, and function of proteins. Synthetic crowders such as dextran, ficoll, polyethylene glycols, polyvinylpyrrolidone, and their respective monomers are used to mimic crowded intracellular environments. Interactions of these synthetic crowders with tryptophan and the subsequent impact on its fluorescence properties are therefore critically important for understanding the possible interference created by these crowders. In the present study, the effects of polymer and monomer crowders on tryptophan fluorescence were assessed by using experimental and computational approaches. The results of this study demonstrated that both polymer and monomer crowders have an impact on the tryptophan fluorescence intensity; however, the molecular mechanisms of quenching were different. Using Stern-Volmer plots and a temperature variation study, a physical basis for the quenching mechanism of commonly used synthetic crowders was established. The quenching of free tryptophan was found to involve static, dynamic, and sphere-of-action mechanisms. In parallel, computational studies employing Kohn-Sham density functional theory provided a deeper insight into the effects of intermolecular interactions and solvation, resulting in differing quenching modes for these crowders. Taken together, the study offers new physical insights into the quenching mechanisms of some commonly used monomer and polymer synthetic crowders.

Drastic Photoemission Color Alternation from a Single Molecule as a Starting Material Introduced in Acid-Treated Zeolites: From Pure Blue to White.

Since high-purity blue- and white-light emitters are an indispensable group of materials for the creation of next-generation optical devices, a number of light-emitting materials have been developed from both inorganic and organic synthetic chemistry. However, these synthetic chemical methods are far from the perspective of green chemistry due to the multistep synthetic process and the use of toxic reagents and elements. Herein, we demonstrate that the introduction of simple unsubstituted anthracenes into zeolite-like pores can create a wide variety of luminescent materials, from ultrapure blue luminescent materials (emission peak at 465 nm with a full width of half-maximum of 8.57 nm) to efficient white luminescent materials [CIE coordination at (0.31, 0.33) with a quantum efficiency of 11.0% under 350 nm excitation light]. The method for rational design of the luminescent materials consists of the following two key strategies: one is molecular orbital confinement of the anthracene molecules in the zeolite nanocavity for regulating the molecular coordination associated with photoexcitation and emission and the other is the interaction of unsubstituted anthracenes with extra-framework aluminum species to stabilize the 2-dehydride anthracene cation in the zeolite cavity.

Intergrowth Zeolites, Synthesis, Characterization, and Catalysis.

Microporous zeolites that can act as heterogeneous catalysts have continued to attract a great deal of academic and industrial interest, but current progress in their synthesis and application is restricted to single-phase zeolites, severely underestimating the potential of intergrowth frameworks. Compared with single-phase zeolites, intergrowth zeolites possess unique properties, such as different diffusion pathways and molecular confinement, or special crystalline pore environments for binding metal active sites. This review first focuses on the structural features and synthetic details of all the intergrowth zeolites, especially providing some insightful discussion of several potential frameworks. Subsequently, characterization methods for intergrowth zeolites are introduced, and highlighting fundamental features of these crystals. Then, the applications of intergrowth zeolites in several of the most active areas of catalysis are presented, including selective catalytic reduction of NOx by ammonia (NH3-SCR), methanol to olefins (MTO), petrochemicals and refining, fine chemicals production, and biomass conversion on Beta, and the relationship between structure and catalytic activity was profiled from the perspective of intergrowth grain boundary structure. Finally, the synthesis, characterization, and catalysis of intergrowth zeolites are summarized in a comprehensive discussion, and a brief outlook on the current challenges and future directions of intergrowth zeolites is indicated.

Activation of Solid-State Emission and Photostability through Molecular Confinement: The Case of Triptycene-Fused Quinacridone Dyes.

We report the facile, metal-free convergent synthesis and the characterization of novel quinacridone dyes in which two triptycene units end-cap and sterically confine the quinacridone chromophore. A precise comparison of the confined dyes with their known homologues reveals that the reduction of π-π interactions in triptycene-fused quinacridone dyes compared to classical quinacridone results not only in an increase of solubility and processability but also in an enhancement of fluorescence quantum yield and photostability in the solid state.

A controllable interface design and manufacturing strategy for embossed glass hierarchical nano-lens

Constructing nanostructured surfaces on the macro/micro-scale optical lens is of great importance in the improvement of light transmittance, reflection, and surface functionality of optical devices. In this paper, a flexible and novel material interface design and manufacturing method for hierarchical macro/nano optical glass lenses is proposed. To verify the feasibility of the presented manufacturing strategy, the deformation history and flow driving mechanism of multiscale structured surfaces during second hot embossing were studied by simulations and experiments. The results showed that solid-like glass preform exhibits a higher nanoscale deformation resistance and elastic recovery, which can reduce the distortion levels of the nanostructured surface. At small scales, molecular confinement greatly reduces the tectonic deformation of nanostructured surface at relatively low applied heat and pressure. However, beyond a specific thermal energy threshold, nanostructured convex surfaces are easily compressed into a smooth flattened surface. By collaborative control of embossing conditions, the nano-surface integrity of multiscale structured surface can be ensured during second hot embossing. Compared to the smooth macroscale optical lens, the hierarchical macro/nano glass lens exhibited better optical transmittance and antireflection properties. The proposed design and manufacturing strategy provides a facile and flexible solution for building the hierarchical macro/micro/nanostructure functional optics.

Anomalous ionic transport in tunable angstrom-size water films on silica

Liquid and ionic transport through nanometric structures is central to many phenomena, ranging from cellular exchanges to water resource management or green energy conversion. While pushing down toward molecular scales progressively unveils novel transport behaviors, reaching ultimate confinement in controlled systems remains challenging and has often involved 2D Van der Waals materials. Here, we propose an alternative route which circumvents demanding nanofabrication steps, partially releases material constraints, and offers continuously tunable molecular confinement. This soft-matter-inspired approach is based on the spontaneous formation of a molecularly thin liquid film onto fully wettable substrates in contact with the vapor phase of the liquid. Using silicon dioxide substrates, water films ranging from angstrom to nanometric thicknesses are formed in this manner, and ionic transport within the film can then be measured. Performing conductance measurements as a function of confinement in these ultimate regimes reveals a one-molecule thick layer of fully hindered transport nearby the silica, above which continuum, bulk-like approaches account for experimental results. Overall, this work paves the way for future investigations of molecular scale nanofluidics and provides insights into ionic transport nearby high surface energy materials such as natural rocks and clays, building concretes, or nanoscale silica membranes used for separation and filtering.