Nitrogen Moieties Research Articles

Engineering cobalt-pyridinic N moieties on hybrid interfaces for alkaline hydrogen evolution

Efficient establishment of transition-metal electrocatalysts is critical for the advancement of clean energy. Herein, we utilize laser ablation to controllably fabricate plenty of cobalt (Co)-pyridinic nitrogen (N) moieties on the hybrid interface between CoO and N-modified graphene with mesoporous-rich architectures. This approach results in a tri-functional catalyst with excellent performance in three crucial electrocatalytic reactions, i.e., hydrogen and oxygen evolution (HER and OER), and oxygen reduction (ORR). More importantly, subsequent control experiments highlight the essential role of Co-pyridinic N bonds in boosting HER. As we previously reported, the catalyst exhibited exceptional performance for oxygen-related catalysis (ORR/OER) in 1.0 M KOH. In this study, it only requires a low exterior voltage of 1.64 V to fulfill the current density of 10 mA cm−2 for driving overall water splitting in the same electrolyte. The Co-pyridinic N moieties present in the catalyst are credited for the superior performance, as they can facilitate the protons adsorption with a decreased Gibbs free energy, and also serve as reaction centers for promoting water dissociation. This study will pave a new avenue for the installation of highly sought-after electrochemical energy technologies.

Application of 15N-Edited 1H-13C Correlation NMR Spectroscopy─Toward Fragment-Based Metabolite Identification and Screening via HCN Constructs.

Many key building blocks of life contain nitrogen moieties. Despite the prevalence of nitrogen-containing metabolites in nature, 15N nuclei are seldom used in NMR-based metabolite assignment due to their low natural abundance and lack of comprehensive chemical shift databases. However, with advancements in isotope labeling strategies, 13C and 15N enriched metabolites are becoming more common in metabolomic studies. Simple multidimensional nuclear magnetic resonance (NMR) experiments that correlate 1H and 15N via single bond 1JNH or multiple bond 2-3JNH couplings using heteronuclear single quantum coherence (HSQC) or heteronuclear multiple bond coherence are well established and routinely applied for structure elucidation. However, a 1H-15N correlation spectrum of a metabolite mixture can be difficult to deconvolute, due to the lack of a 15N specific database. In order to bridge this gap, we present here a broadband 15N-edited 1H-13C HSQC NMR experiment that targets metabolites containing 15N moieties. Through this approach, nitrogen-containing metabolites, such as amino acids, nucleotide bases, and nucleosides, are identified based on their 13C, 1H, and 15N chemical shift information. This approach was tested and validated using a [15N, 13C] enriched Daphnia magna (water flea) metabolite extract, where the number of clearly resolved 15N-containing peaks increased from only 11 in a standard HSQC to 51 in the 15N-edited HSQC, and the number of obscured peaks decreased from 59 to just 7. The approach complements the current repertoire of NMR techniques for mixture deconvolution and holds considerable potential for targeted metabolite NMR in 15N, 13C enriched systems.

CO electroreduction on single-atom copper.

Electroreduction of carbon dioxide (CO2) or carbon monoxide (CO) toward C2+ hydrocarbons such as ethylene, ethanol, acetate and propanol represents a promising approach toward carbon-negative electrosynthesis of chemicals. Fundamental understanding of the carbon─carbon (C-C) coupling mechanisms in these electrocatalytic processes is the key to the design and development of electrochemical systems at high energy and carbon conversion efficiencies. Here, we report the investigation of CO electreduction on single-atom copper (Cu) electrocatalysts. Atomically dispersed Cu is coordinated on a carbon nitride substrate to form high-density copper─nitrogen moieties. Chemisorption, electrocatalytic, and computational studies are combined to probe the catalytic mechanisms. Unlike the Langmuir-Hinshelwood mechanism known for copper metal surfaces, the confinement of CO adsorption on the single-copper-atom sites enables an Eley-Rideal type of C-C coupling between adsorbed (*CO) and gaseous [CO(g)] carbon moxide molecules. The isolated Cu sites also selectively stabilize the key reaction intermediates determining the bifurcation of reaction pathways toward different C2+ products.

Structure-Function Analysis of the S-Glycosylation Reaction in the Biosynthesis of Lincosamide Antibiotics.

The S-glycosyltransferase LmbT, involved in the biosynthesis of lincomycin A, is the only known enzyme that catalyzes the enzymatic incorporation of rare amino acid L-ergothioneine (EGT) into secondary metabolites. Here, we show the structure and function analyses of LmbT. Our in vitro analysis of LmbT revealed that the enzyme shows promiscuous substrate specificity toward nitrogenous base moieties in the generation of unnatural nucleotide diphosphate (NDP)-D-α-D-lincosamides. Furthermore, the X-ray crystal structures of LmbT in its apo form and in complex with substrates indicated that the large conformational changes of the active site occur upon binding of the substrates, and that EGT is strictly recognized by salt-bridge and cation-π interactions with Arg260 and Trp101, respectively. The structure of LmbT in complex with its substrates, the docking model with the EGT-S-conjugated lincosamide, and the structure-based site-directed mutagenesis analysis revealed the structural details of the LmbT-catalyzed SN 2-like S-glycosylation reaction with EGT.

Structure‐Function Analysis of the S‐Glycosylation Reaction in the Biosynthesis of Lincosamide Antibiotics

AbstractThe S‐glycosyltransferase LmbT, involved in the biosynthesis of lincomycin A, is the only known enzyme that catalyzes the enzymatic incorporation of rare amino acid L‐ergothioneine (EGT) into secondary metabolites. Here, we show the structure and function analyses of LmbT. Our in vitro analysis of LmbT revealed that the enzyme shows promiscuous substrate specificity toward nitrogenous base moieties in the generation of unnatural nucleotide diphosphate (NDP)‐D‐α‐D‐lincosamides. Furthermore, the X‐ray crystal structures of LmbT in its apo form and in complex with substrates indicated that the large conformational changes of the active site occur upon binding of the substrates, and that EGT is strictly recognized by salt‐bridge and cation‐π interactions with Arg260 and Trp101, respectively. The structure of LmbT in complex with its substrates, the docking model with the EGT‐S‐conjugated lincosamide, and the structure‐based site‐directed mutagenesis analysis revealed the structural details of the LmbT‐catalyzed SN2‐like S‐glycosylation reaction with EGT.

Understanding ecotoxicological drivers and responses of freshwater green algae, Raphidocelis subcapitata, to cationic polyquaternium polymers

Cationic polymer (CP) ecotoxicity is important to understand and investigate as they are widely used in industrial and consumer applications and have shown toxic effects in some aquatic organisms. CPs are identified as “polymers of concern” and are to be prioritized in upcoming regulatory reviews, (e.g., REACH). Algae have generally been found to be the most sensitive trophic level to CP. This study aimed at elucidating the magnitude of cationic polyquaternium toxicity towards algae and to understand key toxicological drivers. A suite of polyquaterniums with varying charge density (charged nitrogen moieties) and molecular weight were selected. Highly charged polyquaternium-6 and -16 were toxic towards the freshwater green microalgae Raphidocelis subcapitata with ErC50-values ranging between 0.12 and 0.41 mg/L. Lower charge density polyquaternium-10 materials had much lower toxicity with ErC50 > 200 mg/L, suggesting that charge density is an important driver of algal toxicity. These levels of toxicity were in line with historic CP data in literature. Algal agglomeration was observed in all tests but was not linked with impacts on algal growth rate. However, agglomeration can pose challenges in the technical conduct of tests and can impair interpretation of results. The toxicity mitigation potential of humic acid was also explored. The addition of 2–20 mg/L humic acid completely mitigated PQ6 and PQ16 toxicity at concentrations higher than clean water ErC50-values. CP toxicity mitigation has also been observed in fish and invertebrate tests, suggesting that CP mitigation should be accounted for in all trophic levels within an environmental safety framework.

Binuclear transition metal complexes containing 6 N moieties Schiff base ligand: Synthesis, characterization and microbicide activities

ABSTRACT. Complexes of Co(II), Ni(II) and Cu(II) ions with tetra amine hydrazide ligand [H4L] were prepared and characterized using physical and spectral methods. Analytical data showed that the complexes found in (1:2) ligand:metal ratio. Spectral studies revealed that the ligand bonded to the metal ion in neutral tetradentate or tetrabasic tetradentate manner through azomethine nitrogen atom, protonated/deprotonated hydroxyl group. From the electronic spectral data together with magnetic susceptibility values a distorted octahedral structure can be proposed for all complexes except complex 2 which has square planar structure. Electron spin resonance spectra for Co(II) complex 6 revealed axial symmetry with g|| > g⊥ > ge, indicating distorted octahedral or square planar structures and the unpaired electron exists in a d(x2−y2) orbital with marked covalent bond feature. Quantum chemical calculations have been performed to study structures and energetics of the ligand and its complexes. The prepared complexes showed good to excellent antimicrobial activity, and the most active complexes against Aspergillus niger were 3 with zone of inhibition of 23 mm. Complex 7 showed interesting activity against Escherichia coli with zone of inhibition of 23 mm.
 
 KEY WORDS: Metal complexes, Nitrogen moiety, Antimicrobicide activity
 
 Bull. Chem. Soc. Ethiop. 2023, 37(4), 901-915. 
 DOI: https://dx.doi.org/10.4314/bcse.v37i4.8

Ligand engineering with heterocyclic aromatic thiol doped carbon quantum dots

Insights on the origin of photoluminescence (PL) in carbon quantum dots (CQDs) are useful to explore its application in the technological and biomedical fields. Herein, we demonstrate the use of three heterocyclic aromatic thiol ligands (namely, 2-mercaptobenzimidazole (MBI), 2-mercaptobenzothiazole (MBT) and 2-mercaptobenzoxazole (MBO)) doped CQDs (CQDs-MBI, CQDs-MBT and CQDs-MBO) to address the significance of heteroatoms in the optical and electrochemical characteristics of CQDs. Interestingly, we found that nitrogen moieties played a vital role in tailoring the optical and electrochemical properties of CQDs-MBI, CQDs-MBT and CQDs-MBO. Owing to the enriched nitrogen moieties and less surface trap states in CQDs-MBI, which exhibits superior quantum yield (QY) and lifetime than CQDs-MBT and CQDs-MBO. Moreover, for the CQDs-MBI and CQDs-MBT we achieved two sets of emission whereas for the CQDs-MBO attained three sets, also all these CQDs display both excitation independent and dependent emission behavior due to the distinct surface states which is peculiar to existing literature reports. To substantiate the importance of ligand engineering with these three different CQDs, we further investigated the electrochemical characteristics as well. These tunable optical and electrochemical properties of the three different CQDs suggest great scope in the development of new luminescent and sensor materials.

Coordination number engineering of Zn single-atom sites for enhanced transfer hydrogenation performance

Metal single-atom catalysts (SACs) have great potential to replace traditional nanoparticle catalysts in practical applications, however, the task-specific construction of SACs containing metal–nitrogen (M−N) moiety with tunable M−N coordination number remains a colossal challenging issue. Herein, we report a facile strategy to modulate the s-band of Zn by constructing N-coordinated Zn SACs (denoted as Zn–N–C–T, T stands for the pyrolysis temperature) with tunable nitrogen coordination number (denoted as Zn–Nx, x = 2, 3, and 4) and Zn loadings (ranging from 0.8 to 6.8% by weight) via a metal–organic framework-mediated pyrolysis method. The catalytic activity of Zn–N–C–T is found to be closely related to the coordination number of Zn single atomic sites for the transfer hydrogenation of nitroarene to arylamine, using hydrazine hydrate as a hydrogen source under environmental benign conditions, among which the under-coordinated Zn–N3 with defect and asymmetric electron distribution in Zn–N–C–1223 exhibits the best catalytic activity, followed by lower-coordinated Zn–N2 with defect in Zn–N–C–1273 and saturated coordination Zn–N4 in Zn–N–C–1123. Experimental results and theoretical analysis uncover that appropriately lowering the coordination number increases the electron density of Zn single atoms and simultaneously introduces H-acceptor sites, which cooperatively contribute to the enhancement of the performance for transfer hydrogenation.

Operando Studies of Electrochemical Denitrogenation and Its Mitigation of N-Doped Carbon Catalysts in Alkaline Media.

N-doped carbons (NCs) have excellent electrocatalytic performance in oxygen reduction reaction, particularly in alkaline conditions, showing great promise of replacing commercial Pt/C catalysts in fuel cells and metal-air batteries. However, NCs are vulnerable when biased at high potentials, which suffer from denitrogenation and carbon corrosion. Such material degradation drastically undermines the activity, yet its dynamic evolution in response to the applied potentials is challenging to examine experimentally. In this work, we used differential electrochemical mass spectroscopy coupled with an optimized cell and observed the dynamic behaviors of NCs under operando conditions in KOH electrolyte. The corrosion of carbon occurred at ca. 1.2 V vs RHE, which was >0.3 V below the measured onset potential of water oxidation. Denitrogenation proceeded in parallel with carbon corrosion, releasing both NO and NO2. Combined with the ex situ characterizations and density-functional theory calculations, we identified that the pyridinic nitrogen moieties were particularly in peril. Three denitrogenation pathways were also proposed. Finally, we demonstrated that transferring the oxidation reaction sites to the well-deposited metal hydroxide with optimized loading was effective in suppressing the N leaching. This work showed the dynamic evolution of NC under potential bias and might cast light on understanding and mitigating NC deactivation for practical applications.

Conjugated Microporous Polymer Hybrid Microparticles for Enhanced Applicability in Silica‐Boosted Diclofenac Adsorption

Diclofenac (DCF) is one of the most widespread and consumed analgesics, thereby causing contamination of water bodies on a global scale. A common approach to tackle this pressing issue is the adsorption of DCF exploiting highly hydrophobic polymers. However, controlling the morphology of such polymers is essential. Adsorption capacities of the presented conjugated microporous polymer (CMP) in bulk‐form, for DCF (qsat) are as low as 13.0 mg g−1 despite exhibiting additional nitrogen moieties to specifically target DCF. Herein, an approach to drastically increase the DCF adsorption by increasing the accessible hydrophobic surface area by coating it around mesoporous silica microspheres is shown. These microspheres do not attribute to the adsorption of DCF themselves, but increase the accessibility of the CMP. Simultaneously, the applicability of the hybrid material is enhanced through higher wettability and more facile separation. As a consequence, an effective adsorbent is formed featuring an adsorption of up to 422 mg DCF per 1 × g CMP for the optimized silica/monomer ratio — comparable to expensive state‐of‐art materials. As the approach combines the advantages of the nano‐ and the micro‐dimension and does not depend on the actual adsorbent material, it holds great potential for general adsorption problems requiring highly engineered systems.

Urea-doped hierarchical porous carbons derived from sucrose precursor for highly efficient CO2 adsorption and separation

Over the past few years, heteroatom-doped microporous carbons have engrossed significant interest as emergent CO2 adsorbents. However, the clear role of small-sized micropores and heteroatom content on CO2 adsorption is rarely been reported. In this study, a single-step synthetic approach is proposed to prepare a series of sucrose-derived porous carbons by choosing different ratios of KOH and urea (as nitrogen dopant) content (up to ∼ 11 at.%). The role of both KOH and urea variation on textural features (such as specific surface area: SSA, and pore volume: PV) and resultant CO2 adsorption capacity has been studied. Based on KOH and urea content variation, the prepared carbons achieved a remarkable surface area (342-2231 m2g−1), and a large micropore volume (0.24-1.32 cm3g−1). The optimized sample “SUK-113” with sucrose: urea: KOH ratio of 1:1:3 demonstrated a CO2 uptake of 8.19 mmol g−1 at 273K/1 bar. Such remarkable capacity value is accredited to the presence of the highest micropore volume for pores < 1nm for the investigated material. Furthermore, the calculated isosteric heat of adsorption (28.7-34.5 kJ mol−1) and CO2/N2 selectivity (28-137) revealed the significance of nitrogen moieties which offers quadrupole interactions for CO2 molecules and therefore, improved selective separation of CO2 from N2 gases. Conclusively, the narrow micropores and optimum nitrogen content played a decisive role in achieving excellent CO2 adsorption performance in these carbons.

Potential Nitrogen-Based Heterocyclic Compounds for Treating Infectious Diseases: A Literature Review.

Heterocyclic compounds are considered as one of the major and most diverse family of organic compounds. Nowadays, the demand for these compounds is increasing day-by-day due to their enormous synthetic and biological applications. These heterocyclic compounds have unique antibacterial activity against various Gram-positive and Gram-negative bacterial strains. This review covers the antibacterial activity of different heterocyclic compounds with nitrogen moiety. Some of the derivatives of these compounds show excellent antibacterial activity, while others show reasonable activity against bacterial strains. This review paper aims to bring and discuss the detailed information on the antibacterial activity of various nitrogen-based heterocyclic compounds. It will be helpful for the future evolution of diseases to synthesize new and effective drug molecules.

MEGAMOX MEDIATES ECO-FRIENDLY SYNTHESIS OF SELENIUM NANOPARTICLES AS IMMUNOMODULATORY, ANTIOXIDANT AND ANTIMICROBIAL AGENTS

The research herein includes methodology for eco-friendly preparation of selenium nanoparticles (SeNPs) using the broad-spectrum antibiotic, Megamox (Mega.). Characterization of SeNPs was done using UV-Visible spectroscopy, FTIR, XRD, DLS and TEM imaging. Additionally, the immunomodulatory, antioxidant and antimicrobial activities of both SeNPs and Mega. were checked against different strains of bacteria and fungi. TEM and DLS images showed that SeNPs are polydisperse spheres with mean diameter of 22.4 nm. FTIR analysis indicated that the hydroxyl and nitrogen moieties in Mega. were effective for reduction plus binding manner. According to the results of the nitro blue tetrazolium reduction test, both SeNPs and Mega. presented high intracellular killing activity, which confirmed their immunostimulatory effect. Antioxidant activity of SeNPs and Mega. were 90 and 82 %, respectively. SeNPs presented great activity facing multi-drug resistant bacteria and TB. SeNPs are considered promising cost-effective and eco-friendly anti-bacterial and anti-fungal agents that can represent a new potential nano-platform in both medical and infectious diseases control.

Proximity Electronic Effect of Ni/Co Diatomic Sites for Synergistic Promotion of Electrocatalytic Oxygen Reduction and Hydrogen Evolution

AbstractThe modulation effect manifests an encouraging potential to enhance the performance of single‐atom catalysts; however, the in‐depth study about this effect for the isolated diatomic sites (DASs) remains a great challenge. Herein, a proximity electronic effect (PEE) of Ni/Co DASs is proposed that is anchored in N‐doped carbon (N‐C) substrate (NiCo DASs/N‐C) for synergistic promoting electrocatalytic oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). Benefiting from the PEE of adjacent Ni anchored by four nitrogen (Ni‐N4) moiety, NiCo DASs/N‐C catalyst exhibits superior ORR and HER activity. In situ characterization results suggest Co anchored by four nitrogen (Co‐N4) as main active site for O2 adsorption‐activation process, which promotes the formation of key *OOH and the desorption of *OH intermediate to accelerate the multielectron reaction kinetics. Theoretical calculation reveals the adjacent Ni‐N4 site as a modulator can effectively adjust the electronic localization of proximity Co‐N4 site, promoting the *OH desorption and *H adsorption on Co‐N4 site, thereby boosting ORR and HER process significantly. This study opens a new opportunity for rationally regulating the electronic localization of catalytic active centers by proximity single‐atom moiety, as well as provides guidance for designing high‐efficiency bifunctional electrocatalysts for promising applications.

A facile one pot synthesis of biocarbon derived from water hyacinth and development of pellets for CO2 capture applications

In the present work, porous biocarbon with inherent nitrogen is synthesized using a noxious aquatic weed, water hyacinth (Eichhornia crassipes) using a facile and green route. A one-step ZnCl2 activation method, using minimum amount of activating agent at different carbonization temperatures 500 and 600 °C were employed for the production of water hyacinth biocarbon to study the effect of temperature on CO2 adsorption capacity. It is observed that by maintaining an optimum carbonization temperature, the microporosity as well as the nitrogen moieties on the carbon surface can be tuned which in turn influences the CO2 adsorption capacity. The obtained biocarbon was pelletized using non-toxic binders such as sepiolite and carboxymethyl cellulose (CMC) and the effect of binders on thermal stability as well textural properties was evaluated. It is observed that there is a reduction in surface area as well as micropore volume after binder addition due to pore blockage which caused a decline in CO2 adsorption capacity. The water hyacinth biocarbon shows maximum adsorption capacity of 3.2 mmol/g, while water hyacinth biocarbon pellets possess maximum adsorption capacity of 2.6 mmol/g at 298 K and 3 bar. To the best of our knowledge, the development of pellets from water hyacinth as well as its utilization for CO2 capture has not been explored yet.

Nitrogen‐containing heterocycles as topoisomerase II inhibitors for targeting cancer: Recent updates

AbstractCancer is a broad word for a set of diseases that can begin in virtually any organ or tissue of the body and spread to other organs. In 2020, cancer was the largest cause of death worldwide, accounting for 10 million fatalities, or one in every six deaths. Nitrogen containing heterocyclic compounds are a massive research focus because it has a unique position and is a cherished source of a wide range of bioactive molecules in medicinal chemistry. Over 75% of the currently accessible market is covered by FDA‐approved drugs containing nitrogen moieties. DNA topoisomerase II is a reassuring approach for novel anticancer heterocyclic medicines because it plays a crucial role in DNA metabolism, replication, recombination, and repair. Given the importance of topo II in chemotherapy, there is a pressing necessity to boost topo II or multi‐target topo II inhibitors in order to combat drug resistance and minimize toxicity. Following the trend of researching the advancement of effective topo II inhibitors with minimal toxicity, the current review article consolidates a detailed account of nitrogen‐containing heterocyclic compounds and categorizes them into different classes based on structural characterization, such pyrimidine, triazine, pyridine, quinazoline, fluoroquinolones, quinones, pyrazoles, quinoline, carbazoles, β‐carboline, quinolone, naphthalimide, acridone, benzoxazole, pyridophenoxazine, pyrrole, piperazine and imidazole, along with their structure activity relationship, mechanistic aspects, and docking studies (wherever appropriate) were explored. We are certain that the current review paper will help future medical researchers investigate prospective topoisomerase inhibitors as anticancer medicines in a variety of clinical settings.

Discovery of Compounds That Selectively Repress the Amyloidogenic Processing of the Amyloid Precursor Protein: Design, Synthesis and Pharmacological Evaluation of Diphenylpyrazoles

The rationale to define the biological and molecular parameters derived from structure-activity relationships (SAR) is mandatory for the lead selection of small drug compounds. Several series of small molecules have been synthesized based on a computer-assisted pharmacophore design derived from two series of compounds whose scaffold originates from chloroquine or amodiaquine. All compounds share similar biological activities. In vivo, Alzheimer's disease-related pathological lesions are reduced, consisting of amyloid deposition and neurofibrillary degeneration, which restore and reduce cognitive-associated impairments and neuroinflammation, respectively. Screening election was performed using a cell-based assay to measure the repression of Aβ1-x peptide production, the increased stability of APP metabolites, and modulation of the ratio of autophagy markers. These screening parameters enabled us to select compounds as potent non-competitive β-secretase modulators, associated with various levels of lysosomotropic or autophagy modulatory activities. Structure-activity relationship analyses enabled us to define that (1) selectively reducing the production of Aβ1-x, and (2) little Aβx-40/42 modification together with (3) a decreased ratio of p62/(LC3-I/LC3-II) enabled the selection of non-competitive β-secretase modulators. Increased stability of CTFα and AICD precluded the selection of compounds with lysosomotropic activity whereas cell toxicity was associated with the sole p62 enhanced expression shown to be driven by the loss of nitrogen moieties. These SAR parameters are herein proposed with thresholds that enable the selection of potent anti-Alzheimer drugs for which further investigation is necessary to determine the basic mechanism underlying their mode of action.

Nitrogen-Doped Carbon Nanosphere Supports for Platinum-Decorated Oxygen Reduction Reaction Catalysts

Carbonaceous materials are widely used as supports for platinum-based oxygen reduction reaction (ORR) catalysts that are prevalent in proton exchange membrane fuel cells (PEMFC). In particular, a variety of carbon blacks are popular due to factors such as commercial availability and high surface area. However, as applications of PEMFCs shift towards heavy-duty vehicle deployment, durability of the supports has become an important criterion when evaluating materials. Carbon support corrosion can lead to Pt nanoparticle detachment and agglomeration, both of which decrease the electrochemically active surface area of the catalyst. Recently, nitrogen-doping of carbon supports has shown promising results towards improving stability in fuel cell operating conditions1. Graphitization is another strategy that mitigates carbon corrosion, as graphitic carbon is more resistant to oxidation than amorphous carbon2. In this work, we present a set of nitrogen-doped carbon nanosphere supports obtained via a one-pot colloidal synthesis and then decorated with Pt nanoparticles for ORR catalysis (Pt/NCS). The nitrogen-doped supports are monodispersed, contain a mesoporous pore structure, and show a higher level of bulk graphitization than commercial carbon blacks. Our work also elucidates how differences in certain nitrogen moieties on the carbon support’s surface impact catalytic activity. The Pt/NCS catalysts exhibit similar mass activity and improved specific activity in rotating disk electrode measurements compared to a commercial Pt/C catalyst at similar Pt weight loadings.(1) Ott, S.; Orfanidi, A.; Schmies, H.; Anke, B.; Nong, H. N.; Hübner, J.; Gernert, U.; Gliech, M.; Lerch, M.; Strasser, P. Ionomer Distribution Control in Porous Carbon-Supported Catalyst Layers for High-Power and Low Pt-Loaded Proton Exchange Membrane Fuel Cells. Nat. Mater. 2020, 19 (1), 77–85.(2) Yu, P. T.; Gu, W.; Zhang, J.; Makharia, R.; Wagner, F. T.; Gasteiger, H. A. Carbon-Support Requirements for Highly Durable Fuel Cell Operation. In Polymer Electrolyte Fuel Cell Durability; Büchi, F. N., Inaba, M., Schmidt, T. J., Eds.; Springer New York: New York, NY, 2009; pp 29–53.

Structural Studies on Diverse Betacyanin Classes in Matured Pigment-Rich Fruits of Basella alba L. and Basella alba L. var. 'Rubra' (Malabar Spinach).

Identification of betacyanins in Basella alba L. and Basella alba L. var. ‘Rubra’ fruits was performed by low- and high-resolution mass spectrometry (LRMS and HRMS) as well as 1H, 13C and two-dimensional NMR which revealed hitherto completely not known betacyanin classes in the plant kingdom. Especially, the presence of unique nitrogenous acyl moieties in the structures of the pigments was ascertained by the HRMS Orbitrap detection. Except for detected polar betacyanin glycosylated derivatives, presence of a series of previously not reported pigments such as malonylated betanidin 6-O-β-glusosides with their acyl migration isomers along with the evidence of the 3′′-hydroxy-butyrylated betacyanins is reported. The first complete NMR data were obtained for novel and principal acylated gomphrenins with hydroxycinnamic acids: 6′-O-E-caffeoyl-gomphrenin (malabarin), 6′-O-E-sinapoyl-gomphrenin (gandolin), 6′-O-E-4-coumaroyl-gomphrenin (globosin) and 6′-O-E-feruloyl-gomphrenin (basellin).