Chiral induction by the solvent phase offers a promising route to achieve homochirality in self-assembled molecular networks. In this work, we examine solvent-driven chiral induction at the solid-liquid interface, where an enantiopure solvent biases the handedness of two-dimensional (2D) networks formed by achiral molecules physisorbed on the basal plane of highly oriented pyrolytic graphite. Using scanning tunneling microscopy at the liquid-solid interface, we visualize the 2D organization of the achiral monomer 10,12-pentacosadiynoic acid in chiral liquid environments. We compare the induction efficiencies of several enantiopure citronellyl-derived solvents that differ in their capacities for specific solute-solvent interactions. Complementary molecular dynamics simulations provide molecular-level insight into the possible mechanisms of solvent-mediated chiral induction.

Controlling ionic transport in crystalline covalent organic frameworks (COFs) is hindered by long diffusion paths and tortuous pore geometries, limiting their efficacy in ion separations such as sulfate removal from water. Herein, we introduce an ultrasound-assisted synthesis of guanidinium-functionalized ionic COFs, yielding uniform nanospheres (15-120 nm) embedded in larger aggregates with radially accessible pores, in contrast to the fibrous morphologies obtained via conventional hydrothermal methods. This non-equilibrium sonochemical approach, conducted under ambient conditions, affords frameworks with comparable crystallinity and porosity but superior morphological control. The nanospherical COFs exhibit enhanced sulfate adsorption performance, achieving a capacity of 102 mg g-1, rapid equilibration within 20 min (similar to 2.2 & times; faster initial rates than hydrothermal analogs), and a sulfate-chloride selectivity coefficient of 3.6 in mixed solutions. Mechanistic investigations, supported by ball-milling controls, density functional theory calculations (revealing a similar to 5.5-fold stronger binding energy for SO42- over Cl-), and comparative isotherms, demonstrate that the compact morphology minimizes interlayer dislocations and shortens diffusion pathways, enabling monotonic uptake and homogeneous pore accessibility for hydrated multivalent ions. This work establishes a green, energy-efficient strategy for morphology-engineered ionic COFs, providing a generalizable framework to overcome diffusion bottlenecks in 2D porous materials. The insights pave the way for advanced applications in water purification, ion-selective membranes, and electrochemical systems where structure-dynamics coupling is critical.

Diacetylene monomers are known to undergo solid-state 1,4-addition polymerization when their crystal packing satisfies strict geometric criteria; however, the influence of bulky terminal protecting groups on the lattice adjustments required for bond formation remains insufficiently understood. Here, we synthesized amide derivatives of 2,4-hexadiyne-1,6-diamine, crystallized them via antisolvent vapor diffusion, and evaluated their thermal and photochemical reactivity. Single-crystal analysis shows that Boc-protected monomers (Boc-DA) form hydrogen-bond-directed parallel stacks that align diyne units in geometries nominally consistent with topochemical polymerization, yet they exhibit negligible photoreactivity under ambient UV irradiation. Structural inspection indicates that steric congestion from the tert-butoxycarbonyl termini restricts the subtle axial contraction and molecular shifts required for bond formation. Reducing steric bulk or applying combined thermal and photochemical activation enables polymerization of these diacetylenes. These findings demonstrate that globally favorable packing arrangements can coexist with local steric barriers that impose kinetic constraints on reactivity. Modulating terminal-group size and applying multimodal activation therefore provide a simple and tunable strategy to control diacetylene polymerization, offering design principles for switchable polydiacetylene materials in crystal engineering.

Reversible transitions of surface-adsorbed molecules under external stimuli hold great promise for advancing nanotechnology. Electric fields, in particular, can provide highly localized and tunable forces, enabling on-demand manipulation of molecular assembly and reactivity. However, despite extensive studies, the mechanism governing bias-induced phase transitions in surface-confined systems, particularly those involving neutral molecules like boronic acids, remains ambiguous. Addressing this gap is crucial for the rational design of tunable molecular assemblies. Here, we employ a competitive adsorption strategy to investigate the electric field-mediated switching of multicomponent systems comprising boronic acids and an inert reference compound at the liquid-solid interface. Using scanning tunneling microscopy (STM), we uncovered distinct bias-dependent behaviors, including reversible dynamic exchange and phase transitions. Our findings identify partial ionization as a key mechanism driving the dynamic exchange and structural transformations of boronic acids.

The performance of electrochemical (bio)sensors is fundamentally determined by the precise engineering of interfacial layers that govern (bio)analyte–surface interactions. However, elucidating structure–function relationships remains challenging due to the complex architecture of modern sensors and the irregular nanoscale morphology of many high-performance materials. In this study, we present a strategy for designing custom functional interfaces as well-defined platforms for probing interfacial processes. Focusing on epinephrine (EP) detection as an important representative of catecholamines, we compare the interfacial behavior of two carboxy-functionalized electrodes—grafted with either para-aminobenzoic acid (PAB) or 3,4,5-tricarboxybenzenediazonium (ATA)—against atomically flat highly oriented pyrolytic graphite (HOPG) as a control. While both modifiers introduce carboxyl groups, PAB forms disordered multilayers that inhibit surface responsiveness, whereas ATA yields an ultrathin monolayer with accessible COOH groups. Electrochemical analysis reveals that ATA-HOPG significantly enhances EP detection at sub-micromolar levels, facilitated by electrostatic interactions between surface-bound COO− and protonated EP and its redox products. These results demonstrate that nanoscale control of diazonium grafting is crucial for optimizing bioanalyte recognition. More broadly, this work highlights how molecular-level surface engineering on high-quality carbon substrates can serve as a test-bed platform for the rational design of advanced electrochemical sensing interfaces.

Gentle annealing and photopolymerization under inert atmospheres strongly enhance the quality of polydiacetylene monolayers. These simple measures not only triple the average degree of polymerization but also alter the preferred photoexcitation mode and cause pronounced nano-alignment during the early stages of polymerization.

A simple, inexpensive and versatile patterned removal of C–C grafts has been realized for scalable multicomponent micropatterned functionalization.

Since 2012, when triboelectric nanogenerators (TENGs) were first reported by Wang and co-workers, various applications have taken advantage of their ability to transform mechanical energy into electrical energy. TENG applications cover many fields, including electronics, physics, materials science, and engineering. The differences in the language used in various research fields makes understanding TENG concepts rather challenging for those outside of the domain. This article provides a practical introduction to triboelectric nanogenerators by applying an inquiry-based learning (IBL) strategy to the assembly and characterization of easily customizable paper-based TENGs. This will allow junior researchers from different fields of materials chemistry to become familiar with the terminology and basic concepts of TENGs, experimentally validate the triboelectric properties of different materials, and construct their first electromechanical sensors and micropower generators.

Chemical upcycling that catalyzes waste plastics back to high-purity chemicals holds great promise in end-of-life plastics valorization. One of the main challenges in this process is the thermodynamic limitations imposed by the high intrinsic entropy of polymer chains, which makes their adsorption on catalysts unfavorable and the transition state unstable. Here, we overcome this challenge by inducing the catalytic reaction inside mesoporous channels, which possess a strong confined ability to polymer chains, allowing for stabilization of the transition state. This approach involves the synthesis of p-Ru/SBA catalysts, in which Ru nanoparticles are uniformly distributed within the channels of an SBA-15 support, using a precise impregnation method. The unique design of the p-Ru/SBA catalyst has demonstrated significant improvements in catalytic performance for the conversion of polyethylene into high-value liquid fuels, particularly diesel. The catalyst achieved a high solid conversion rate of 1106 g ⋅ g Ru −1  ⋅ h −1 at 230 °C. Comparatively, this catalytic activity is 4.9 times higher than that of a control catalyst, Ru/SiO 2 , and 14.0 times higher than that of a commercial catalyst, Ru/C, at 240 °C. This remarkable catalytic activity opens up immense opportunities for the chemical upcycling of waste plastics.

Self-assembled molecular networks (SAMNs) are formed by the spontaneous assembly of molecules on surfaces. On conductive atomically flat surfaces, and also at the liquid-solid interface, scanning tunneling microscopy (STM) can follow their growth dynamics. Desorption and adsorption dynamics are difficult to probe through the liquid-solid interface. Porous molecular networks are of particular interest because they may act as platforms for sensing and host-guest chemistry. Very little is known though about their stability, particularly in a liquid environment. To this end, we have investigated the desorption/adsorption dynamics of supramolecular porous monolayers of alkoxylated dehydrobenzo[12]annulene (DBA) derivatives at the interface between highly oriented pyrolytic graphite, the substrate, and 1-phenyloctane, the liquid. To trace the dynamics, structurally analogous chiral DBA derivatives were used as marker molecules, which co-assemble with the achiral ones forming the supramolecular network. This approach reveals the time scales of the adsorption/desorption dynamics, the significance of temperature, and the important role of the STM tip in inducing dynamics.

Herein we report the impact of covalent modification (grafting), inducing lateral nanoconfinement conditions, on the self-assembly of a quinonoid zwitterion derivative into self-assembled molecular networks at the liquid/solid interface. At low concentrations where the compound does not show self-assembly behaviour on bare highly oriented pyrolytic graphite (HOPG), close-packed self-assembled structures are visualized by scanning tunneling microscopy on covalently modified HOPG. The size of the self-assembled domains decreases with increasing the density of grafted molecules, i.e. the molecules covalently bound to the surface. The dynamics of domains are captured with molecular resolution, revealing not only time-dependent growth and shrinkage processes but also the orientation conversion of assembled domains. Grafted pins play a key role in initiating the formation of on-surface molecular self-assembly and their stabilization, providing an elegant route to study various aspects of nucleation and growth processes of self-assembled molecular networks.

We report on the detection and stabilization of a previously unknown two-dimensional (2D) pseudopolymorph of an alkoxy isophthalic acid using lateral nanoconfinement. The self-assembled molecular networks formed by the isophthalic acid derivative were studied at the interface between covalently modified graphite and an organic solvent. When self-assembled on graphite with moderate surface coverage of covalently bound aryl groups, a previously unknown metastable pseudopolymorph was detected. This pseudopolymorph, which was presumably "trapped" in between the surface bound aryl groups, underwent a time-dependent phase transition to the stable polymorph typically observed on pristine graphite. The stabilization of the pseudopolymorph was then achieved by using an alternative nanoconfinement strategy, where the domains of the pseudopolymorph could be formed and stabilized by restricting the self-assembly in nanometer-sized shallow compartments produced by STM-based nanolithography carried out on a graphite surface with a high density of covalently bound aryl groups. These experimental results are supported by molecular mechanics and molecular dynamics simulations, which not only provide important insight into the relative stabilities of the different structures, but also shed light onto the mechanism of the formation and stabilization of the pseudopolymorph under nanoscopic lateral confinement.

Structurally precision graphene nanoribbons (GNRs) are promising candidates for next-generation nanoelectronics due to their intriguing and tunable electronic structures. GNRs with hybrid edge structures often confer them unique geometries associated with exotic physicochemical properties. Herein, a novel type of cove-edged GNRs with periodic short zigzag-edge segments is demonstrated. The bandgap of this GNR family can be tuned using an interplay between the length of the zigzag segments and the distance of two adjacent cove units along the opposite edges, which can be converted from semiconducting to nearly metallic. A family member with periodic cove-zigzag edges based on N = 6 zigzag-edged GNR, namely 6-CZGNR-(2,1), is successfully synthesized in solution through the Scholl reaction of a unique snakelike polymer precursor (10) that is achieved by the Yamamoto coupling of a structurally flexible S-shaped phenanthrene-based monomer (1). The efficiency of cyclodehydrogenation of polymer 10 toward 6-CZGNR-(2,1) is validated by FT-IR, Raman, and UV-vis spectroscopies, as well as by the study of two representative model compounds (2 and 3). Remarkably, the resultant 6-CZGNR-(2,1) exhibits an extended and broad absorption in the near-infrared region with a record narrow optical bandgap of 0.99 eV among the reported solution-synthesized GNRs. Moreover, 6-CZGNR-(2,1) exhibits a high macroscopic carrier mobility of ∼20 cm2 V-1 s-1 determined by terahertz spectroscopy, primarily due to the intrinsically small effective mass (m*e = m*h = 0.17 m0), rendering this GNR a promising candidate for nanoelectronics.

A convenient covalent functionalization approach and nanopatterning method of graphite and graphene is developed. In contrast to expectations, electrochemically activated dediazotization of a mixture of two aryl diazonium compounds in aqueous media leads to a spatially inhomogeneous functionalization of graphitic surfaces, creating covalently modified surfaces with quasi-uniform spaced islands of pristine graphite or graphene, coined nanocorrals. Cyclic voltammetry and chronoamperometry approaches are compared. The average diameter (45-130 nm) and surface density (20-125 corrals/μm2) of these nanocorrals are tunable. These chemically modified nanostructured graphitic (CMNG) surfaces are characterized by atomic force microscopy, scanning tunneling microscopy, Raman spectroscopy and microscopy, and X-ray photoelectron spectroscopy. Mechanisms leading to the formation of these CMNG surfaces are discussed. The potential of these surfaces to investigate supramolecular self-assembly and on-surface reactions under nanoconfinement conditions is demonstrated.

By using a novel protocol to spatially confine molecules in well-defined small 2D areas, the so-called nanocorrals, we show using scanning tunneling microscopy (STM) how this kind of confinement affects self-assembled molecular network (SAMN) formation at a liquid-solid interface. The 2D lateral confinement, imposed by the size of the nanocorrals, has a clear impact on the phase selectivity of a molecule that can form both low-density and high-density SAMNs, the high-density phase being promoted by the confinement.

Halogen bonding has emerged as a promising tool in two-dimensional (2D) crystal engineering. Since halogen bonds are similar to hydrogen bonds in a number of aspects, the existing knowledge of hydrogen bonded systems can be applied to halogenated systems. Here we evaluate the applicability of a retrosynthetic approach based on topological similarity between hydrogen and halogen bonds to obtain predictable halogen bonded networks. The self-assembly of 1,3-dibromo-5-alkoxybenzene derivatives was studied in analogy with well-explored alkoxy isophthalic acids using a combination of experimental and theoretical tools. Scanning tunneling microscopy (STM) characterization of the networks formed at the liquid-graphite interface revealed that while the retrosynthetic approach works at the level of small clusters of molecules within the 2D network, the overall structure of the network deviates from the anticipated structure. The monolayers consist of fractured rows of halogen-bonded modules instead of the expected continuous lamellar structure. Each module consists of a discrete number of halogen-bonded molecules. The interactions responsible for the stabilization of halogen bonded dimers are delineated through detailed density functional theory (DFT) calculations coupled with natural bonding orbitals (NBO) and perturbation analysis. A modified force field that includes an extra charged site to imitate the σ hole on the halogen atom was developed and applied to extract total potential energies of the anticipated and observed networks. Plausible reasons for the deviation from the anticipated structure are discussed. Finally, a modified molecular design that allows successful application of the hydrogen bond-halogen bond analogy was tested experimentally.

Halogen bonding has emerged as a promising tool in two-dimensional (2D) crystal engineering. Since halogen bonds are similar to hydrogen bonds in a number of aspects, the existing knowledge of hydrogen bonded systems can be applied to halogenated systems. Here we evaluate the applicability of a retrosynthetic approach based on topological similarity between hydrogen and halogen bonds to obtain predictable halogen bonded networks. The self-assembly of 1,3-dibromo-5-alkoxybenzene derivatives was studied in analogy with well-explored alkoxy isophthalic acids using a combination of experimental and theoretical tools. Scanning tunneling microscopy (STM) characterization of the networks formed at the liquid–graphite interface revealed that while the retrosynthetic approach works at the level of small clusters of molecules within the 2D network, the overall structure of the network deviates from the anticipated structure. The monolayers consist of fractured rows of halogen-bonded modules instead of the expected continuous lamellar structure. Each module consists of a discrete number of halogen-bonded molecules. The interactions responsible for the stabilization of halogen bonded dimers are delineated through detailed density functional theory (DFT) calculations coupled with natural bonding orbitals (NBO) and perturbation analysis. A modified force field that includes an extra charged site to imitate the s hole on the halogen atom was developed and applied to extract total potential energies of the anticipated and observed networks. Plausible reasons for the deviation from the anticipated structure are discussed. Finally, a modified molecular design that allows successful application of the hydrogen bond–halogen bond analogy was tested experimentally.

We demonstrate ultrasensitive detection of malaria aptamers performed with the help of graphene protected copper plasmonics. Using better morphology of copper surface as compared to gold, phase sensitive surface plasmon resonance schemes and graphene functionalization protocol for attaching end-tethering of DNA probes we were able to improve the detection level of malaria aptamers by an order of magnitude. This opens a way to associate a dormant bacterial population with chronic inflammatory diseases in blood samples using simple label-free optical detection.

In this chapter we give an overview of different chemical transformations that can be done on graphene layers and characterized using scanning tunneling (STM) and atomic force microscopies (AFM). We place particular emphasis on the diversity of reactions, systems and synthetic strategies that are now available to surface scientists working in various fundamental and applied research fields. Using imine formation as the model reaction we discuss common principles of building block design and reaction outcomes specific to interfacial synthesis. Then other reactions are briefly overviewed, including: photo- and electrochemically assisted processes, transformations initiated by STM, and finally, reactions involving the covalent modification of graphene layers.