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The design of novel carbon dots with ad hoc properties requires a comprehensive understanding of their formation mechanism, which is a complex task considering the number of variables involved, such as reaction time, structure of precursors or synthetic protocol employed. Herein, we systematically investigated the formation of carbon nanodots by tracking structural, chemical and photophysical features during the hydrothermal synthesis. We demonstrate that the formation of carbon nanodots consists of 4 consecutive steps: (i) aggregation of small organic molecules, (ii) formation of a dense core with an extended shell, (iii) collapse of the shell and (iv) aromatization of the core. In addition, we provide examples of routes towards tuning the core-shell design, synthesizing five novel carbon dots that all consist of an electron-dense core covered by an amine rich ligand shell. Studying the formation processes of carbon nanodots remains crucial for understanding their properties and chemical structure. Here, the authors investigate the steps involved in their formation process and provide examples for tuning the core-shell design.

Scanning tunnelling microscopy (STM) is commonly used to identify on-surface molecular self-assembled structures. However, its limited ability to reveal only the overall shape of molecules and their relative positions is not always enough to fully solve a supramolecular structure. Here, we analyse the assembly of a brominated polycyclic aromatic molecule on Au(111) and demonstrate that standard STM measurements cannot conclusively establish the nature of the intermolecular interactions. By performing high-resolution STM with a CO-functionalised tip, we clearly identify the location of rings and halogen atoms, determining that halogen bonding governs the assemblies. This is supported by density functional theory calculations that predict a stronger interaction energy for halogen rather than hydrogen bonding and by an electron density topology analysis that identifies characteristic features of halogen bonding. A similar approach should be able to solve many complex 2D supramolecular structures, and we predict its increasing use in molecular nanoscience at surfaces. Scanning tunnelling microscopy (STM) is commonly used to study 2D molecular self-assembly but is not always enough to fully solve a supramolecular structure. Here, the authors combine a high-resolution version of STM with first-principles simulations to precisely identify halogen bonding in polycyclic aromatic molecules.

Carbon nanodots with opposite chirality possess the same major physicochemical properties such as optical features, hydrodynamic diameter, and colloidal stability. Here, a detailed analysis about the comparison of the concentration of both carbon nanodots is carried out, putting a threshold to when differences in biological behavior may be related to chirality and may exclude effects based merely on differences in exposure concentrations due to uncertainties in concentration determination. The present study approaches this comparative analysis evaluating two basic biological phenomena, the protein adsorption and cell internalization. We find how a meticulous concentration error estimation enables the evaluation of the differences in biological effects related to chirality. Chirality is known to impact the biological activity of materials but concentration differences can often lead to errors in analysis. Here, the authors report on detailed concertation analysis of different chiral carbon nanodots to accurately investigate chiral effects on the protein absorption and cell internalisation.

Photoluminescent carbon nanoparticles, or carbon dots, are an emerging class of materials that has recently attracted considerable attention for biomedical and energy applications. They are defined by characteristic sizes of <10 nm, a carbon-based core and the possibility to add various functional groups at their surface for targeted applications. These nanomaterials possess many interesting physicochemical and optical properties, which include tunable light emission, dispersibility and low toxicity. In this Review, we categorize how chemical tools impact the properties of carbon dots. We look for pre- and postsynthetic approaches for the preparation of carbon dots and their derivatives or composites. We then showcase examples to correlate structure, composition and function and use them to discuss the future development of this class of nanomaterials. This Review discusses synthetic strategies to functionalize photoluminescent carbon nanomaterials, or carbon dots, for targeted applications.

Carbon-based dots (CDs) and their functionalized (nano)composites have recently attracted attention due to their seemingly easy preparation and numerous potential applications, ranging from those in the biomedical field (i.e., imaging and drug delivery) to those in (opto)electronics (i.e., solar cells and LEDs). This protocol details step-by-step procedures for synthesis, purification, functionalization and characterization of nitrogen-doped carbon nanodots (NCNDs), which we have been preparing for the past few years. First, we describe the bottom-up synthesis of NCNDs, starting with the use of molecular precursors (arginine (Arg) and ethylenediamine (EDA)) and making use of microwave-assisted hydrothermal heating. We also provide guidelines for the purification of these materials, through either dialysis or low-pressure size-exclusion chromatography (SEC). Second, we outline post-functionalization procedures for the surface modification of NCNDs, such as alkylation and amidation reactions. Third, we provide instructions for the preparation of NCNDs with different properties, such as color emission, electrochemistry and chirality. Given the fast evolution of preparations and applications of CDs, issues that might arise from artifacts, errors and impurities should be avoided. In this context, the present protocol aims to provide details and guidelines for the synthesis of high-quality nanomaterials with high reproducibility, for various applications. Furthermore, specific needs might require the CDs to be prepared by different synthetic procedures and/or from different molecular precursors, but such CDs can still benefit from the purification and characterization procedures outlined in this protocol. The sample preparation takes various time frames, ranging from 4 to 18 d, depending on the adopted synthesis and purification steps. This protocol describes the synthesis, purification, functionalization and characterization of nitrogen-doped carbon nanodots (NCNDs). In addition, examples of how to tailor the color emission, electrochemistry and chirality of NCNDs are provided.

This paper explores the application of predictive maintenance (PdM) to address paraffin deposition in sucker rod pump systems used for oil production. System maintenance has become critical for enhancing efficiency and reducing costs, while PdM, supported by advanced analytics and sensors, enables downtime prediction and maintenance optimization. Paraffin deposition is a significant problem in the oil industry, as it diminishes production capacity and increases expenses. This paper presents the use of the SCADA system, which enables the collection and analysis of data in real time. Furthermore, it proposes diagnostic methods for early detection of paraffin deposition using predictive maintenance, offering timely warnings to prevent production delays. While the proposed framework relies on interpretable statistical and physics-informed predictive models, the results indicate that further improvements could be achieved by integrating advanced artificial intelligence techniques to enhance adaptability, automation, and decision support in predictive maintenance systems.

The preparation and characterisation of a novel three‐dimensional organic material consisting of porphyrin arrays on carbon nanotubes embedded in an organogel is reported. Firstly, the porphyrin array was prepared through metal‐ligand coordination of a ditopic ligand (1,2‐bis(4‐pyridyl)ethane) and two bis‐Zn(II) porphyrins, linked through a pyrene core, and was studied through UV‐Vis, NMR and diffusion spectroscopies. Secondly, the porphyrin supramolecular architecture was adsorbed on pristine carbon nanotubes, greatly improving the dispersibility of the latter in organic solvents. The hybrid material was characterised by means of UV‐Vis spectroscopy, microscopic techniques and thermogravimetric analysis. Finally, by exploiting the anisotropic magnetic susceptibility of carbon nanotubes, the hybrid material was aligned under a magnetic field, the organisation of which could be maintained by in situ gelation. The resultant hybrid organogel exhibited notable optical anisotropy, suggesting an anisotropic arrangement of the porphyrin‐CNTs architectures in the macroscopic material. Controlled organization: A three‐dimensional organogel, which consists of porphyrin arrays adsorbed on carbon nanotubes, was prepared and characterized (see Figure). The magnetic susceptibility of the nanotubes was exploited to prepare an organogel with notable optical anisotropy.

The chirality of (nano)structures is paramount in many phenomena, including biological processes, self-assembly, enantioselective reactions, and light or electron spin polarization. In the quest for new chiral materials, metallo-organic hybrids have been attractive candidates for exploiting the aforementioned scientific fields. Here, we show that chiral carbon nanoparticles, called carbon nanodots, can be readily prepared using hydrothermal microwave-assisted synthesis and easily purified. These particles, with a mean particle size around 3 nm, are highly soluble in water and display mirror-image profile both in the UV–Vis and in the infrared regions, as detected by electronic and vibrational circular dichroism, respectively. Finally, the nanoparticles are used as templates for the formation of chiral supramolecular porphyrin assemblies, showing that it is possible to use and transfer the chiral information. This simple (and effective) methodology opens up exciting opportunities for developing a variety of chiral composite materials and applications. A promising and efficient route to chiral materials involves the transfer of chirality across length scales. Here, the authors use chiral molecular precursors to synthesize chiral carbon nanodots, which in turn can template the formation of chiral supramolecular assemblies.

The production of polymers from ethylene requires the ethylene feed to be sufficiently purified of acetylene contaminant. Accomplishing this task by thermally hydrogenating acetylene requires a high temperature, an external feed of H 2 gas and noble-metal catalysts. It is not only expensive and energy-intensive, but also prone to overhydrogenating to ethane. Here we report a photocatalytic system that reduces acetylene to ethylene with ≥99% selectivity under both non-competitive (no ethylene co-feed) and competitive (ethylene co-feed) conditions, and near 100% conversion under the latter industrially relevant conditions. Our system uses a molecular catalyst based on earth-abundant cobalt operating under ambient conditions and sensitized by either [Ru(bpy) 3 ] 2+ or an inexpensive organic semiconductor (metal-free mesoporous graphitic carbon nitride) under visible light. These features and the use of water as a proton source offer advantages over current hydrogenation technologies with respect to selectivity and sustainability. The acetylene contaminant present in ethylene feeds used to produce polymers is typically removed by thermal hydrogenation. Now, it has been shown that the conversion of acetylene to ethylene at room temperature can be achieved in a visible-light-driven process using an earth-abundant metal (cobalt) catalyst and a water proton source.

Donor–acceptor (D–A) architectures underpin many high-performance conjugated polymers but remain largely unexplored in atomically precise nanoribbons. Here, we report the on-surface synthesis of ultra-narrow D–A nanoribbons using two complementary brominated precursors based on the electron donor peri-xanthenoxanthene and the acceptor anthanthrone. High-resolution scanning tunnelling microscopy, non-contact atomic force microscopy and scanning tunnelling spectroscopy reveal submolecular structural and electronic features of the resulting nanoribbons. Homopolymerisation of each precursor yields structurally well-defined donor-only and acceptor-only nanoribbons, whose electronic character strengthens with length. Co-deposition of both precursors produces mixed D–A nanoribbons with tuneable electronic structures governed by monomer sequence. The spatial character and energetic alignment of their frontier orbitals match gas-phase density functional theory calculations, while a simplified linear combination of molecular orbitals model captures dominant trends. This bottom-up synthetic strategy enables precise control over nanoribbon composition and functionality, offering a versatile platform for engineering π-conjugated nanostructures with tailored optoelectronic properties. Donor–acceptor architectures underpin many high-performance conjugated polymers but remain largely unexplored in atomically precise nanoribbons. Here, the authors report an on-surface strategy to synthesize ultra-narrow donor–acceptor nanoribbons with sequence-controlled electronic structure.