JACS Au

Journal: JACS Au

Abbreviation

JACS Au

Publisher

American Chemical Society

ISSN

2691-3704

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Publications 1 - 10 of 35

Multifunctional Catalyst Combination for the Direct Conversion of CO2 to Propane
Ramirez Galilea, Adrian; Ticali, Pierfrancesco; Salusso, Davide; et al. (2021)
JACS Au
The production of carbon-rich hydrocarbons via CO2 valorization is essential for the transition to renewable, non-fossil-fuel-based energy sources. However, most of the recent works in the state of the art are devoted to the formation of olefins and aromatics, ignoring the rest of the hydrocarbon commodities that, like propane, are essential to our economy. Hence, in this work, we have developed a highly active and selective PdZn/ZrO2+SAPO-34 multifunctional catalyst for the direct conversion of CO2 to propane. Our multifunctional system displays a total selectivity to propane higher than 50% (with 20% CO, 6% C1, 13% C2, 10% C4, and 1% C5) and a CO2 conversion close to 40% at 350 °C, 50 bar, and 1500 mL g–1 h–1. We attribute these results to the synergy between the intimately mixed PdZn/ZrO2 and SAPO-34 components that shifts the overall reaction equilibrium, boosting CO2 conversion and minimizing CO selectivity. Comparison to a PdZn/ZrO2+ZSM-5 system showed that propane selectivity is further boosted by the topology of SAPO-34. The presence of Pd in the catalyst drives paraffin production via hydrogenation, with more than 99.9% of the products being saturated hydrocarbons, offering very important advantages for the purification of the products.
Solid-state NMR spectra of protons and quadrupolar nuclei at 28.2 T: Resolving signatures of surface sites with fast magic angle spinning
Berkson, Zachariah J.; Björgvinsdóttir, Snædís; Yakimov, Alexander; et al. (2022)
JACS Au
Advances in solid-state nuclear magnetic resonance (NMR) methods and hardware offer expanding opportunities for analysis of materials, interfaces, and surfaces. Here, we demonstrate the application of a very high magnetic field strength of 28.2 T and fast magic-angle-spinning rates (MAS, >40 kHz) to surface species relevant to catalysis. Specifically, we present as case studies the 1D and 2D solid-state NMR spectra of important catalyst and support materials, ranging from a well-defined silica-supported organometallic catalyst to dehydroxylated γ-alumina and zeolite solid acids. The high field and fast-MAS measurement conditions substantially improve spectral resolution and narrow NMR signals, which is particularly beneficial for solid-state 1D and 2D NMR analysis of 1H and quadrupolar nuclei such as 27Al at surfaces.
Uncovering the CO2 Capture Mechanis of NaNO3-Promoted MgO by O-18 Isotope Labeling
Landuyt, Annelies; Kumar, Priyank V.; Yuwono, Jodie A.; et al. (2022)
JACS Au
MgO-based CO2 sorbents promoted with molten alkali metal nitrates (e.g., NaNO3) have emerged as promising materials for CO2 capture and storage technologies due to their low cost and high theoretical CO2 uptake capacities. Yet, the mechanism by which molten alkali metal nitrates promote the carbonation of MgO (CO2 capture reaction) remains debated and poorly understood. Here, we utilize O-18 isotope labeling experiments to provide new insights into the carbonation mechanism of NaNO3-promoted MgO sorbents, a system in which the promoter is molten under operation conditions and hence inherently challenging to characterize. To conduct the O-18 isotope labeling experiments, we report a facile and large-scale synthesis procedure to obtain labeled MgO with a high O-18 isotope content. We use Raman spectroscopy and in situ thermogravimetric analysis in combination with mass spectrometry to track the O-18 label in the solid (MgCO3), molten (NaNO3), and gas (CO2) phases during the CO2 capture (carbonation) and regeneration (decarbonation) reactions. We discovered a rapid oxygen exchange between CO2 and MgO through the reversible formation of surface carbonates, independent of the presence of the promoter NaNO3. On the other hand, no oxygen exchange was observed between NaNO3 and CO2 or NaNO3 and MgO. Combining the results of the O-18 labeling experiments, with insights gained from atomistic calculations, we propose a carbonation mechanism that, in the first stage, proceeds through a fast, surface-limited carbonation of MgO. These surface carbonates are subsequently dissolved as [Mg2+center dot center dot center dot CO32-] ionic pairs in the molten NaNO3 promoter. Upon reaching the solubility limit, MgCO3 crystallizes at the MgO/NaNO3 interface.
Designing a Multifunctional Catalyst for the Direct Production of Gasoline-Range Isoparaffins from CO2
Dokania, Abhay; Ould-Chikh, Samy; Ramirez Galilea, Adrian; et al. (2021)
JACS Au
The production of carbon-neutral fuels from CO2 presents an avenue for causing an appreciable effect in terms of volume toward the mitigation of global carbon emissions. To that end, the production of isoparaffin-rich fuels is highly desirable. Here, we demonstrate the potential of a multifunctional catalyst combination, consisting of a methanol producer (InCo) and a Zn-modified zeolite beta, which produces a mostly isoparaffinic hydrocarbon mixture from CO2 (up to ∼85% isoparaffin selectivity among hydrocarbons) at a CO2 conversion of >15%. The catalyst combination was thoroughly characterized via an extensive complement of techniques. Specifically, operando X-ray absorption spectroscopy (XAS) reveals that Zn (which plays a crucial role of providing a hydrogenating function, improving the stability of the overall catalyst combination and isomerization performance) is likely present in the form of Zn6O6 clusters within the zeolite component, in contrast to previously reported estimations.
Engineering the Distinct Structure Interface of Subnano-alumina Domains on Silica for Acidic Amorphous Silica–Alumina toward Biorefining
Wang, Zichun; Buechel, Robert; Jiang, Yijiao; et al. (2021)
JACS Au
Amorphous silica–aluminas (ASAs) are important solid catalysts and supports for many industrially essential and sustainable processes, such as hydrocarbon transformation and biorefining. However, the wide distribution of acid strength on ASAs often results in undesired side reactions, lowering the product selectivity. Here we developed a strategy for the synthesis of a unique class of ASAs with unvarying strength of Brønsted acid sites (BAS) and Lewis acid sites (LAS) using double-flame-spray pyrolysis. Structural characterization using high-resolution transmission electron microscopy (TEM) and solid-state nuclear magnetic resonance (NMR) spectroscopy showed that the uniform acidity is due to a distinct nanostructure, characterized by a uniform interface of silica–alumina and homogeneously dispersed alumina domains. The BAS population density of as-prepared ASAs is up to 6 times higher than that obtained by classical methods. The BAS/LAS ratio, as well as the population densities of BAS and LAS of these ASAs, could be tuned in a broad range. In cyclohexanol dehydration, the uniform Brønsted acid strength provides a high selectivity to cyclohexene and a nearly linear correlation between acid site densities and cyclohexanol conversion. Moreover, the concerted action of these BAS and LAS leads to an excellent bifunctional Brønsted–Lewis acid catalyst for glucose dehydration, affording a superior 5-hydroxymethylfurfural yield.
A Perspective on Unintentional Fragments and Their Impact on the Dark Metabolome, Untargeted Profiling, Molecular Networking, Public Data, and Repository Scale Analysis
El Abiead, Yasin; Mohanty, Ipsita; Xing, Shipei; et al. (2025)
JACS Au
In/postsource fragments (ISFs) arise during electrospray ionization or ion transfer in mass spectrometry when molecular bonds break, generating ions that can complicate data interpretation. Although ISFs have been recognized for decades, their contribution to untargeted metabolomics-particularly in the context of the so-called "dark matter" (unannotated MS or MS/MS spectra) and the "dark metabolome" (unannotated molecules)-remains unsettled. This ongoing debate reflects a central tension: while some caution against overinterpreting unidentified signals lacking biological evidence, others argue that dismissing them too quickly risks overlooking genuine molecular discoveries. These discussions also raise a deeper question: what exactly should be considered part of the metabolome? As metabolomics advances toward large-scale data mining and high-throughput computational analysis, resolving these conceptual and methodological ambiguities has become essential. In this perspective, we propose a refined definition of the "dark metabolome" and present a systematic overview of ISFs and related ion forms, including adducts and multimers. We examine their impact on metabolite annotation, experimental design, statistical analysis, computational workflows, and repository-scale data mining. Finally, we provide practical recommendations-including a set of dos and do nots for researchers and reviewers-and discuss the broader implications of ISFs for how the field explores unknown molecular space. By embracing a more nuanced understanding of ISFs, metabolomics can achieve greater rigor, reduce misinterpretation, and unlock new opportunities for discovery.
SNAPpa: A Photoactivatable SNAP-tag for the Spatiotemporal Control of Protein Labeling
Mandl, Sabrina; Maiwald, Barbara; Adlmanninger, Elena; et al. (2025)
JACS Au
SNAP-tag is one of the most commonly used self-labeling protein tags for cell imaging studies. To achieve selective spatiotemporal imaging of cells, we set out to engineer a photoactivatable SNAP-tag. For this, we incorporated the well-established and readily available photocaged unnatural amino acid o-nitrobenzyl-O-tyrosine (ONBY) into all three tyrosine positions of SNAP. In-gel imaging analysis and fluorescence polarization measurements revealed that placing ONBY in position Y114 of the SNAP-tag facilitates the most effective and most efficient photoactivation of the irreversible self-labeling reaction with (sulfonated) benzyl guanine substrates, which is why we dubbed this photoactivatable SNPA-tag variant "SNAPpa". To demonstrated its potential for live-cell imaging, we further tested SNAPpa in HEK293 cells, either fused to a nuclear localization domain for intracellular imaging or fused to either a transmembrane region or the glucagon-like peptide 1 receptor for extracellular imaging. Each SNAPpa construct produced no fluorescence signal when ONBY remained in its photocaged state by keeping the cells in the dark. However, a clear fluorescence signal appeared after light-induced decaging of ONBY. Applying a localized light beam thereby highlighted the precise spatiotemporal control of cell imaging. In conclusion, SNAPpa can be used for the efficient light-induced activation of fluorescence labeling and can be easily established, readily implemented and effectively combined with the broad repertoire of substrates that is already available for SNAP.
Unexpected Disparity in Photoinduced Reactions of C60 and C70 in Water with the Generation of O2•– or 1O2
Liosi, Korinne; Stasyuk, Anton J.; Masero, Fabio; et al. (2021)
JACS Au
Well-defined fullerene-PEG conjugates, C60-PEG (1) and two C70-PEG (2 and 3 with the addition sites on ab-[6,6] and cc-[6,6]-junctions), were prepared from their corresponding Prato monoadduct precursors. The resulting highly water-soluble fullerene-PEG conjugates 1–3 were evaluated for their DNA-cleaving activities and reactive oxygen species (ROS) generation under visible light irradiation. Unexpectedly, photoinduced cleavage of DNA by C60-PEG 1 was much higher than that by C70-PEG 2 and 3 with higher absorption intensity, especially in the presence of an electron donor (NADH). The preference of photoinduced ROS generation from fullerene-PEG conjugates 1–3 via the type II (energy transfer) or the type I (electron transfer) photoreaction was found to be dependent on the fullerene core (between C60 and C70) and functionalization pattern of C70 (between 2 and 3). This was clearly supported by the electron transfer rate obtained from cyclic voltammetry data and computationally estimated relative rate of each step of the type II and the type I reactions, with the finding that type II energy transfer reactions occurred in the inverted Marcus regime while type I electron transfer reactions proceeded in the normal Marcus regime. This finding on the disparity in the pathways of photoinduced reactions (type I versus type II) provides insights into the behavior of photosensitizers in water and the design of photodynamic therapy drugs.
Xanthene[n]arenes: Exceptionally Large, Bowl Shaped Macrocyclic Building Blocks Suitable for Self-Assembly
Pfeuffer-Rooschüz, Jonathan; Schmid, Lucius; Prescimone, Alessandro; et al. (2021)
JACS Au
A new class of macrocycles denoted as "xanthene[n]arenes" was synthesized. In contrast to most other macrocycles, they feature a conformationally restricted bowl shape due to the attached alkyl groups at the linking methylene units. This facilitates the synthesis of cavitands and the self-assembly to molecular capsules via noncovalent interactions. The derivatization potential of the novel macrocycles was demonstrated on the xanthene[3]arene scaffold. Besides a deep cavitand and an oxygen-embedded zigzag hydrocarbon belt[12]arene, a modified macrocycle was synthesized that self-assembles into a hydrogen-bonded tetrameric capsule, demonstrating the potential of xanthene[n]arenes as a new set of macrocydic building blocks.
Role of Na2CO3 as Nucleation Seeds to Accelerate the CO2 Uptake Kinetics of MgO-Based Sorbents
Landuyt, Annelies; Kochetygov, Ilia; McMonagle, Charles J.; et al. (2024)
JACS Au
There is an urgent need for inexpensive, functional materials that can capture and release CO2 under industrial conditions. In this context, MgO is a highly promising, earth-abundant CO2 sorbent. However, despite its favorable carbonation thermodynamics and potential for high gravimetric CO2 uptakes, MgO-based CO2 sorbents feature slow carbonation kinetics, limiting their CO2 uptake during typical industrial contact times. The addition of molten alkali metal nitrate promoters, such as NaNO3, can partially mitigate the slow kinetics. Here, we investigate how the CO2 uptake kinetics of NaNO3-promoted MgO can be increased further through the addition of finely dispersed Na2CO3. The incorporation of Na2CO3 significantly increases the CO2 uptake rate from 1.4 to 14.6 mmol MgCO3 (mol MgO)−1 s–1. Using in situ synchrotron X-ray powder diffraction (XRD), we track the formation of MgCO3 and elucidate the mechanism through which Na2CO3 promotes the CO2 uptake of MgO. Our findings demonstrate that Na2CO3 rapidly converts within seconds into Na2Mg(CO3)2 during carbonation, acting subsequently as nucleation seeds for MgCO3 formation, in turn significantly enhancing CO2 uptake kinetics. Further, the presence of Na2Mg(CO3)2 considerably enhances the mobility of ions in the sorbent, leading to sintering of MgCO3. Importantly, Na2Mg(CO3)2 promotes MgCO3 formation even in the presence of molten RbNO3, a salt with a limited ability to dissolve [Mg2+···CO32–] ion pairs, indicating that Na2Mg(CO3)2 lowers the critical ion pair concentration required for MgCO3 nucleation. Additionally, the partial dissolution of Na2CO3 in NaNO3 may increase the concentration of carbonate ions in the melt, further accelerating carbonation kinetics in MgO-(Na2CO3/NaNO3)

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