76 results match your criteria: "University of Amsterdam Science Park 904[Affiliation]"

The development of sustainable synthetic methods for converting alcohols to amines is of great interest due to their widespread use in pharmaceuticals and fine chemicals. In this work, we present an electrochemical approach by using green electrons for the selective oxidation of benzyl alcohol to benzaldehyde using a NiOOH catalyst, followed by its reductive amination to form benzyl--butylamine. The number of Ni monolayer equivalents on the catalyst was found to significantly influence selectivity, with 2 monolayers achieving up to 90% faradaic efficiency (FE) for benzaldehyde in NaOH, while 10 monolayers performed best in a -butylamine solution (pH 11), yielding 100% FE for benzaldehyde.

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Inflammatory diseases of the human gastrointestinal tract are affected by the microbes that reside in the mucosal surfaces. Patients with inflammatory bowel diseases (IBD) have altered bacterial and fungal intestinal compositions, including higher levels of fecal Candida yeasts. Ongoing research indicates that genetic and phenotypic diversity of Candida albicans may be linked with disease severity.

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Giese-type alkylation of dehydroalanine derivatives via silane-mediated alkyl bromide activation.

Beilstein J Org Chem

December 2024

Department of Chemical and Geological Sciences, University of Cagliari, S.S. 554, bivio per Sestu, 09042 Monserrato (CA), Italy.

The rising popularity of bioconjugate therapeutics has led to growing interest in late-stage functionalization (LSF) of peptide scaffolds. α,β-Unsaturated amino acids like dehydroalanine (Dha) derivatives have emerged as particularly useful structures, as the electron-deficient olefin moiety can engage in late-stage functionalization reactions, like a Giese-type reaction. Cheap and widely available building blocks like organohalides can be converted into alkyl radicals by means of photoinduced silane-mediated halogen-atom transfer (XAT) to offer a mild and straightforward methodology of alkylation.

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Near-infrared light-activated photocages enable controlling molecules with tissue penetrating light. Understanding the structural aspects that govern the photouncaging process is essential to enhancing their efficacy, crucial for practical applications. Here we explore the impact of thermodynamic stabilization on contact ion pairs in cyanine photocages by quaternarization of the carbon reaction centers.

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Enhancement of the ionic conductivity and reduction of diffusion barriers of lithium-ion batteries are crucial for improving the performance of the fast-growing energy storage devices. Recently, the fast-charging capability of commercial-like lithium-ion anodes with the smallest modification of the current manufacturing technology has been of great interest. We used first principles methods computations with density functional theory and the climbing image-nudged elastic band method to evaluate the impact of an external electric field on the stability, electronic band gap, ionic conductivity, and lithium-ion diffusion coefficient of penta-graphene nanoribbons upon lithium adsorption.

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Renewable polyesters with a good balance between impact strength and elastic modulus (stiffness) are not very common, especially when combined with high glass transition temperature ( ). Achieving such high performance properties would enable the substitution of high performance polymers like ABS and polycarbonate with chemically recyclable polyesters from bio-based or recycled sources. One of the challenges in developing these materials is to select the right composition of the right monomers/comonomer ratios and making these materials with high molecular weight, which can be challenging since some of the most promising rigid diols, such as isosorbide, are unreactive.

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Photoinduced halogen-atom transfer (XAT) has rapidly emerged as a programmable approach to generate carbon-centered radical intermediates, mainly relying on silyl and α-aminoalkyl radicals as halogen abstractors. More recently, ligated boryl radicals have also been proposed as effective halogen abstractors under visible-light irradiation. In this study, we describe the use of this approach to enable C(sp)-C(sp) bond formation radical addition of carbon-centered radicals generated XAT onto chloroalkynes.

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Visible-light-operated photoswitches are of growing interest in reversibly controlling molecular processes, enabling for example the precise spatiotemporal focusing of drug activity and manipulating the properties of materials. Therefore, many research efforts have been spent on seeking control over the (photo)physical properties of photoswitches, in particular the absorption maxima and the half-life. For photopharmacological applications, photoswitches should ideally be operated by visible light in at least one direction, and feature a metastable isomer with a half-life of 0.

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Plastic material performance is strongly correlated to the polymer's molecular weight. Obtaining a sufficiently high molecular weight is therefore a key goal of polymerization processes. The most important polyester polyethylene terephthalate (PET) and the new polyethylene furanoate (PEF) require metal catalysts and time-consuming production processes to reach sufficiently high molecular weights.

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The local coordination environment of single atom catalysts (SACs) often determines their catalytic performance. To understand these metal-support interactions, we prepared Pt SACs on cerium dioxide (CeO) cubes, octahedra and rods, with well-structured exposed crystal facets. The CeO crystals were characterized by SEM, TEM, pXRD, and N sorption, confirming the shape-selective synthesis, identical bulk structure, and variations in specific surface area, respectively.

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NiO electrodes are widely applied in p-type dye-sensitized solar cells (DSSCs) and photoelectrochemical cells, but due to excessive charge recombination, the efficiencies of these devices are still too low for commercial applications. To understand which factors induce charge recombination, we studied electrodes with a varying number of NiO layers in benchmark P1 p-DSSCs. We obtained the most efficient DSSCs with four layers of NiO (0.

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The light-induced photocycloaddition of 9,10-phenanthrenequinone (PQ) with electron-rich alkenes (ERA), known as the PQ-ERA reaction, is a highly attractive photoclick reaction characterized by its operational simplicity and high biocompatibility. One essential aspect of photoclick reactions is their high rate, however the limited solubility of PQs often requires the use of a co-solvent. Evaluating the effect of different co-solvents on the PQ-ERA reaction and their influence on the reaction rate, we discovered that sulfur-containing compounds, in particular the frequently used solubilizing co-solvent DMSO, quench the triplet state of the PQ.

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Molecular photoswitches are potent tools to construct dynamic functional systems and responsive materials that can be controlled in a non-invasive manner. As P-type photoswitches, stiff-stilbenes attract increasing interest, owing to their superiority in quantum yield, significant geometric differences between isomers, excellent thermostability and robust switching behavior. Nevertheless, the UV-light-triggered photoisomerization of stiff-stilbenes has been a main drawback for decades as UV light is potentially harmful and has low penetration depth.

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The adsorptive separation of ternary propyne (CH)/propylene (CH)/propane (CH) mixtures is of significant importance due to its energy efficiency. However, achieving this process using an adsorbent has not yet been accomplished. To tackle such a challenge, herein, we present a novel approach of fine-regulation of the gradient of gate-opening in soft nanoporous crystals.

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To reduce global CO emissions in line with EU targets, it is essential that we replace fossil-derived plastics with renewable alternatives. This provides an opportunity to develop novel plastics with improved design features, such as better reusability, recyclability, and environmental biodegradability. Although recycling and reuse of plastics is favoured, this relies heavily on the infrastructure of waste management, which is not consistently advanced on a worldwide scale.

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Caged complexes can provide impressive selective catalysts. Due to the complex shapes of such caged catalysts, however, the level of selectivity control of a single substrate cannot be extrapolated to other substrates. Herein, the substrate scope using 41 terminal alkene substrates is investigated in the hydroformylation reaction with an encapsulated rhodium catalyst [Rh(H)(CO)(P(Py(ZnTPP)))] ().

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Article Synopsis
  • Hydrogen peroxide (HO) is a green oxidant with potential as an energy carrier, and its photochemical production is a more sustainable alternative to traditional methods that are wasteful and energy-intensive.* -
  • Researchers developed iron oxide nanoparticles that effectively produce HO using visible light, achieving over 99% purity and allowing for catalyst recycling up to four times.* -
  • The study demonstrated a productivity rate of at least 1.7 mmol g L h for HO production, with further feasibility under sunlight and seawater conditions, and introduced a proposed mechanism based on experimental and computational findings.*
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In this contribution, we describe a post-assembly modification approach to selectively coordinate transition metals in PdL cuboctahedra. The herein reported approach involves the preparation of PdL nanospheres with protonated nitrogen donor ligands that are covalently linked at the interior. The so obtained Pd(LH) nanospheres are shown to be suitable for coordinative post-modification after deprotection by deprotonation.

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Surface engineering on a microporous metal-organic framework to boost ethane/ethylene separation under humid conditions.

Chem Sci

November 2023

College of Chemistry and Materials Science, Guangdong Provincial Key Laboratory of Functional Supramolecular Coordination Materials and Applications, Jinan University Guangzhou 510632 P. R. China

Recently, examples of metal-organic frameworks (MOFs) have been identified displaying ethane (CH) over ethylene (CH) adsorption selectivity. However, it remains a challenge to construct MOFs with both large CH adsorption capacity and high CH/CH adsorption selectivity, especially under humid conditions. Herein, we reported two isoreticular MOF-5 analogues (JNU-6 and JNU-6-CH) and their potential applications in one-step separation of CH from CH/CH mixtures.

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Article Synopsis
  • Supramolecular cages are gaining popularity because they can hold catalysts that benefit from confinement effects, enhancing their performance in chemical reactions.
  • The study focuses on a PdL cage that has gold complexes fixed at its windows, showing improved reactivity and selectivity in cyclization reactions compared to standalone catalysts due to effective substrate arrangement.
  • The unique structure of the cage prevents the formation of less effective dinuclear gold complexes, improving stability in water and suggesting a catalytic mechanism similar to enzymatic processes.
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Nanoconfined Water Clusters in Zinc White Oil Paint.

J Phys Chem C Nanomater Interfaces

September 2023

Van 't Hoff Institute for Molecular Sciences, University of Amsterdam Science Park 904, 1098 XH Amsterdam, The Netherlands.

Pigments in oil paint are bound by a complex oil polymer network that is prone to water-related chemical degradation. We use cryo-Fourier-transform infrared spectroscopy and differential scanning calorimetry to study how water distributes inside zinc white oil paint. By measuring water freezing and melting transitions, we show that water-saturated zinc white oil paint contains both liquid-like clustered water and nonclustered water.

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We present a class of visible-light-driven molecular motors based on barbituric acid. Due to a serendipitous reactivity we observed during their synthesis, these motors possess a tertiary stereogenic centre on the upper half, characterised by a hydroxy group. Using a combination of femto- and nanosecond transient absorption spectroscopy, molecular dynamics simulations and low-temperature H NMR experiments we found that these motors operate similarly to push-pull second-generation overcrowded alkene-based molecular motors.

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Article Synopsis
  • The PQ-ERA reaction is a promising light-activated reaction that combines 9,10-phenanthrenequinone with electron-rich alkenes, noted for its selectivity, control with light, and compatibility with biological systems.
  • Researchers found that substituting thiophene at the 3-position of the PQ structure significantly increases the reactivity of the PQ triplet state, overcoming limitations in traditional PQ compounds.
  • This enhancement leads to impressive outcomes, including high reaction efficiency (quantum yield up to 98%), increased reaction rates, and good performance in the presence of oxygen, supported by experimental and theoretical findings.
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There is an increasing interest in the application of metal-organic cages (MOCs) in a biomedicinal context, as they can offer non-classical distribution in organisms compared to molecular substrates, while revealing novel cytotoxicity mechanisms. Unfortunately, many MOCs are not sufficiently stable under conditions, making it difficult to study their structure-activity relationships in living cells. As such, it is currently unclear whether MOC cytotoxicity stems from supramolecular features or their decomposition products.

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