NH Groups Research Articles

One‐Pot Multicomponent Reactions for the Synthesis and Biological Study of Novel Dihydrocyclopenta[b]pyrrole Employing Ag/Fe3O4@MWCNTs

ABSTRACTThe primary objective of this study was to explore the synthesis of novel dihydrocyclopenta[b]pyrrole derivatives with a high degree of efficiency. The work utilized a nanocatalyst composed of Ag/Fe3O4@MWCNTs in a multicomponent reaction including vinilydene aldehydes, ethyl 2‐amino‐4‐dioxo‐4‐arylbutanoates, and alkyl bromides. The reaction was carried out in aqueous solution at ambient temperature, leading to the formation of novel chemicals. The produced compounds exhibit antioxidant activity as a result of the evaluation processes performed on their NH group. Furthermore, an evaluation was performed on the antibacterial effectiveness of newly produced pyridines using a disk diffusion technique, utilizing two different strains of Gram‐negative bacteria. Significantly, the substances that were evaluated shown inhibitory effects on the development of Gram‐positive bacteria as well. This method has several benefits, including quick response times, high product yields, and easy separation of catalyst and product through simple procedures.

Superior proton conductivity of amino acid-modified UiO-66-(COOH)2 embedded in chitosan: Mechanistic insights into the acid-base interactions

We focus on optimizing acid-base interactions and hydrogen bonding networks to achieve enhanced proton conductivity under low relative humidity (RH) and high temperature. By functionalizing UiO-66-(COOH)2 with glutamic acid (Glu) and lysine (Lys), we generate Glu-UiO-66-(COOH)2 and Lys-UiO-66-(COOH)2. These modified materials are subsequently incorporated into chitosan (CS) to produce the composites Glu-UiO-66-(COOH)2@CS and Lys-UiO-66-(COOH)2@CS. The successful incorporation of amino acids and cross-linking between -COOH and -NH2 groups in the composites, confirmed by FTIR and PXRD analyses, significantly enhances the structural integrity and durability by strengthening the network, and reducing polymer chain mobility. Proton conductivity assessments reveal that Lys-UiO-66-(COOH)2@CS-7 exhibits a remarkable conductivity of 0.022 S/cm at 100 % RH and 363 K, outperforming Glu-UiO-66-(COOH)2@CS-7. The lower activation energy (Ea) of 0.28 eV for Lys-UiO-66-(COOH)2@CS-7, compared to 0.336 eV for Glu-UiO-66-(COOH)2@CS-7, highlights the significant improvement in intramolecular acid-base interactions and hydrogen bonding. Furthermore, Lys-UiO-66-(COOH)2@CS-7 maintains notable proton conductivity at 43 % RH, with an Ea of 0.216 eV, demonstrating its efficacy in low-humidity conditions. These findings underscore the profound impact of amino acid modifications and cross-linking on proton conductivity by reinforcing acid-base interactions, hydrogen bonding networks, and proton transfer efficiency.

Storehouse of Peculiar Supramolecular Architecture: Probing the Charge-Transfer Phenomenon and Effect of Altering the pH in a Meta-Oriented Single Donor-Double Acceptor Fluorophore.

The investigation of excited-state intramolecular charge transfer (ESICT) has been a fascinating area of research. Although the ESICT events have been studied mostly for para-disubstituted donor-acceptor type molecules, the meta-oriented donor-acceptor type molecules have also shown tremendous potential as ESICT active molecules. In the current work, a small fluorescent probe diethyl 5-amino isophthalate (DE-5A-IPA) was investigated as a potential model to investigate ESICT events in the solution as well as solid phase. DE-5A-IPA was synthesized easily starting from commercially available 5-amino isophthalic acid in excellent yield. In the solid state, differing extents of CH···π-type binding led to formation of fully planar and puckered "cyclobutane" mimic supramolecular architecture, as evidenced from the crystal structure analysis. In addition, the single crystal structure of DE-5A-IPA shows that the donor (-NH2) and acceptor (-CO2Et) are situated in the same plane, thereby assuring the prerequisites of a through-space charge transfer. DE-5A-IPA undergoes noticeable Stokes shift (in cm-1) when the polarity of the medium was changed (4820 cm-1 in hexane; 9375 cm-1 in water). The excited-state dipole moment (μe) was calculated to be 4.0 units higher than the ground-state dipole moment (μg). DE-5A-IPA had an appreciable quantum yield (0.10 ± 0.03 to 0.27 ± 0.04). The ESICT phenomenon was also investigated by ground- and excited-state structural calculations using Gaussian 16 software. The excited-state lifetime measured by the time correlated single photon counting technique was found to vary with the polarity of the solvent, thereby providing further support to the ESICT phenomenon being operative in DE-5A-IPA. Taking advantage of the -NH2 group (which is susceptible to protonation) in DE-5A-IPA, steady state and time-resolved photodynamics were investigated in solutions of varying pH values. Interestingly, the emission quantum yields as well as the emission lifetime increase with an increase in pH value, thereby establishing DE-5A-IPA as a pH-sensitive probe. The current findings shall boost the understanding of meta-oriented ESICT enabled compounds in terms of their excited-state photophysics.

Earth-abundant catalyst for modification of wheat straw to enhance ammonia mitigation from fertilized alkaline soil

In this study, inexpensive earth-abundant catalyst of Co/TiO2 is coupled with a low-temperature modification approach to enhance NH3 adsorption capacity on wheat straw (WS). The highest NH3 uptake achieved is 111.9 mg/g, with 80.8 % retention even after 3 h of desorption. Mechanistic investigation indicates that the enhanced adsorption capacity stems from Co/TiO2, which facilitates generation of reactive oxygen species, leading improved ultra-micropore structure that enhances the interaction between NH3 and oxygen-containing functional groups through a trapping effect. The robust stability of adsorbed NH3 is attributed to the formation of amides or amines. Incorporation of only 1 wt% WS-Co to urea-fertilized alkaline soil reduced NH3 volatilization by 83.1 %. The significant effect is primarily attributed to the excellent adsorption capacity of WS-Co, rather than alterations in the relative abundance of the microbial community. These findings present a novel approach for development of effective fertiliser additive to mitigate NH3 volatilization from alkaline soil.

Synthesis of CdS QDs/NH2-Nb2O5 via electrostatic self-assembly method for highly efficient photocatalytic removal of NO and synchronous inhibition of NO2

A two-step electrostatic self-assembly method was used to first graft –NH2 groups onto the Nb2O5 followed by loading of CdS QDs onto the NH2-Nb2O5 to obtain CdS/NH2-Nb2O5. The performance of the samples under visible light was evaluated under simulated conditions of 25 °C and varying relative humidity (RHs). The results showed that with the increase of RH, the NO removal efficiency by CdS/NH2-Nb2O5 increased first and then decreased, reaching the maximum NO removal efficiency when RH = 50 %. The selectivity of NO2 on CdS/NH2-Nb2O5 (9.01 %) was significantly lower compared to that of Nb2O5 (24.44 %) and NH2-Nb2O5 (19.72 %). The introduction of –NH2 groups and CdS QDs significantly enhanced visible light absorption and improved the separation efficiency of photogenerated charge carriers. In-situ DRIFTS analysis revealed that Cd2+ served as an additional active site for NO adsorption. Furthermore, CdS had a relatively negative conduction band position, which was conducive to the generation of O2–, further inhibiting the generation of NO2. This work provides a new approach to the design and preparation of catalysts for photocatalytic oxidation of NO.

Cationic-Modified diatomite as a novel carrier Material for enhanced Microbial-Induced carbonate precipitation in soil reinforcement

To address the low loading efficiency of mineralizing bacteria on conventional bio-carriers, a novel microbial carrier (SMD) was developed by cationically modifying diatomite with amino-modifying agents. The modification degree and surface potential of SMD were assessed using FT-IR and Zeta potential analysis, while thermogravimetric analysis and SEM evaluated the immobilization of mineralizing bacteria. The results indicated that SMD successfully grafted abundant –NH2 groups and, due to their protonation characteristics, carried a positive charge in solutions with a pH below 8.26. A significant amount of negatively charged Sporosarcina pasteurii (S.p) was firmly adsorbed onto the surface of SMD through Coulombic interactions. Compared to the unmodified carrier, the calcium carbonate content generated on the SMD surface after microbial-induced carbonate precipitation (MICP) treatment increased from 12.6% to 23.7%. Furthermore, soil reinforcement experiments demonstrated that this innovative bio-carrier significantly enhanced the repair efficiency of large-diameter pores in the soil, outperforming traditional MICP treatments.

Highly stable scalable production of porous graphene-polydopamine nanocomposites for drug molecule sensing

As atenolol overdosing can lead to severe health complications, the rapid detection of atenolol intake in point-of-care settings is highly desirable. The recent advancement of redox analytical methodologies has facilitated the efficacious quantification of these compounds for drug analysis, but their performance still presents challenges in practical applications. This study addresses these challenges by controlling the electropolymerization of polydopamine (PDA) on highly porous laser-induced graphene (LIG) electrodes with enhanced electrochemical redox activity for the detection of drug molecules such as atenolol, with minimized interference with the other active substances to induce variation of electrochemical behavior. The enhanced sensitivity of atenolol is attributed to the superhydrophilicity and increased number of active surface sites and -NH2 groups in the PDA polymer through a controlled polymerization process. Moreover, the simulation results further reveal that highly sensitive sensing of atenolol molecules relies on optimal adsorption of the atenolol molecule on dopamine or dopaminequinone structural units. The resulting sensors with high repeatability and reproducibility can achieve a low detection limit of 80 μM and a sensitivity of 0.020 ± 0.04 μA/μM within a linear range from 100 to 800 μM. The materials and surface chemistry in the electrode design based on highly porous LIG provide insights into the integration and application of future scalable and cost-effective electrochemical sensors for use in point-of-care or in-field applications.

The impact of organic matter and iron/calcium coupling on phosphorus retention in the hyporheic zone of the Danjiangkou area tributary: Evidence from bonding recognition

The coupling between organic matter (OM) and minerals considerably influences the phosphorus (P) cycle within the hyporheic zone, but the role of different geological mineral-organic complexes (MOCs) on P burial during hyporheic exchange remains under-explored. This study investigates the effects of OM and iron (Fe)/calcium (Ca) coupling on P migration within the hyporheic zone of an agricultural tributary to the Danjiangkou Reservoir. These relationships were explored by measuring hyporheic flow (q), organic and inorganic P forms, and sediment PO4-P adsorption capacity [following treatment with fulvic acid (FA), Fe-OM, or Ca-OM]. Multivariate statistical analysis, X-Ray Diffraction, Fourier-transform Infrared Spectroscopy, and X-ray Photoelectron Spectroscopy were employed to elucidate the underlying mechanisms. Results indicate that upward hyporheic flow transports dissolved porewater P into surface water, contributing 11.27–12.13 % of the total P flux. MOCs associated with Fe(III)/Ca silicate minerals, along with FA and labile OM, were identified as key OM fractions influencing P migration, contributing 5–24 %, 10–11.7 %, and 6–14.9 % to the overall flux, respectively. FA and labile OM facilitate P release, whereas MOCs enhance P retention. Ca-OM is the most efficient PO4-P adsorption [adsorption capacity (AC): 0.8980–0.9524 mg/g], followed by Fe-OM (AC: 0.5120–0.7020 mg/g), original sediment (AC: 0.4368–0.5596 mg/g), and FA (AC: 0.2657–0.2769 mg/g). Cation bridges, primarily formed by -OH and -NH2 groups within Ca-OM (outer-sphere complexes), promote greater P adsorption than Fe-OM (inner-sphere complexes, mainly associated with -COOH). However, Fe-OM-P exhibits a more stable structure. In high P environments, P adsorption onto Ca-OM may induce the release of labile OM, temporarily retaining P through resorption onto labile OM. Hyporheic flow with higher pH and Eh values promotes MOC formation, underscoring their significant P retention capacity. Therefore, strategic MOC use within the hyporheic zone is crucial for mitigating surface water eutrophication.

Modification of Chitosan Isolation Method from Pearl Oyster Shell (Pinctada maxima sp) as A Source of Natural Polymer

Abstract Chitosan is natural polymer with abundant availability and unique characteristics. The purpose of this study was to investigate the effects of various isolation methods on chitosan properties. Chitosan was obtained by isolation method using oyster pearl shell (Pinctada maxima sp.). The parameters of the deacetylation process are the comparison of heating method with microwave method and the comparison of microwave power. Chitosan was characterized for degree of deacetylation (DD) and functional groups by FTIR, and viscosity by Brookfield viscometer. The microwave method was faster than the heating method. Then, the larger mass of shell and %NaOH produced a higher DD of 89.75%. However, the use of 60g mass and 60% NaOH resulted in an already high DD of 81.96%. Furthermore, variation microwave power showed the highest DD at high power. FTIR spectrum analysis showed the appearance of chitosan functional groups, OH and NH2 groups. The viscosity value decreased as the microwave power increased. Based on this study, different isolation methods affect the quality of chitosan. However, it’s necessary to conduct more detailed research related to changes in chemical structure. Therefore, oyster shells can produce chitosan as a source of natural polymers with different characteristics.

Polydopamine modified carbon fiber to improve the comprehensive properties of carbon paper for proton exchange membrane fuel cell

In this study, polydopamine (PDA) was used to modify functional groups on the surface of carbon fiber (CF), and the effects of different dopamine hydrochloride (DPH) concentrations on the surface morphology, functional groups, contact angle and dispersion stability of CF were studied. Subsequently, the raw carbon paper (RCP), hot-pressed carbon paper (HPCP) and carbon paper (CP) were prepared successively using the modified CF through wet forming, impregnation/hot-pressing, and carbonization methods. The surface morphology, tensile strength, flexural strength, electrical resistivity, air permeability and pore size distribution were analyzed for these materials. It was observed that the introduction of −OH and − NH2 groups improved the hydrophilicity and dispersion of PDA modified CFs, resulting in an increase in formation index (FI) from 39.2 to 48.1 for RCP samples. With increasing DPH concentration, the tensile strength of CP initially increased but then decreased while its electrical resistivity showed an opposite trend. Finally, PDA modified CP was assembled into proton exchange membrane fuel cells (PEMFC). The PEMFC assembled from DPH-CP-2.5 achieved a maximum limiting current density of 1440.0 mA/cm2 and power density of 458.25 mW/cm2. Meanwhile, the lower material transmission impedance for DPH-CP-2.5 as well as excellent water management ability and gas transmission performance.

Synthesis, X-ray structures, and anion binding properties of 1,8-disulfonamidocarbazole-di(thio)amide hybrid macrocycles

An easy-to-prepare 1,8-disulfonamidocarbazole-diamide hybrid macrocycle 1 and its thioamide analogue 2 were reported, along with their anion recognition properties as determined by UV-vis and 1H NMR spectroscopic titrations as well as single crystal X-ray diffraction analyses. The conversion of amides into thioamides in the macrocyclic structures generated notable effects on the anion-binding affinity and selectivity. For example, amide-bearing macrocycle 1 was found to bind H2PO4- over one order of magnitude more strongly than thioamide-containing macrocycle 2, despite having more acidic NH groups for the latter. Additionally, macrocycle 1 displayed the highest affinity for PhCOO- in DMSO (Ka >105 M-1 for the formed 1:1 complex) followed by H2PO4- and AcO- ions, whereas a different binding order AcO- > PhCOO- >> H2PO4- was observed for macrocycle 2. More importantly, the single crystal X-ray diffraction analysis clearly revealed that macrocycle 1 indeed formed a 1:1 complex with PhCOO- ion in the solid state.

A terphenyl derivative-based colorimetric-fluorimetric probe for the detection of lysine and arginine and their bioimaging

Lysine (Lys) and arginine (Arg) play a crucial role in the human diets, medical diagnostics, and functional biomaterial synthesis. The imbalance of intake for these two amino acids causes various diseases. Although many analytical techniques have been reported for the detection of amino acids, there are still some issues such as the need for bulky instruments, professional operators, sensitivity to be improved, and real-time detection. Here, a novel colorimetric-fluorimetric probe based on a terphenyl derivative (TPT) has been synthesized for the precise detection of Lys and Arg. In the EtOH-H2O solution of TPT, the NH2 group at the chain end of Lys/Arg undergoes a nucleophilic addition reaction with CN groups of benzothiazole groups of the probe TPT, which breaks the initial long-conjugated system of the probe molecule. As a result, blue shifts can be observed for both UV–vis absorption spectra and fluorescence spectra, accompanying with color changes of the TPT solution. The UV–vis absorption peak of TPT solution shifts from ∼410 nm to ∼325 nm, and the solution color changes from light-yellow to colorless. The fluorescence emission shifts from ∼580 nm to ∼470 nm and the bright-yellow TPT solution changes to blue under the irradiation of 365 nm UV light. For colorimetric method, the limits of detection (LoD) are 0.82 μM and 0.90 μM for Lys and Arg, respectively. For fluorimetric method, they are 2.02 nM and 1.62 nM for Lys and Arg, respectively. In addition, TPT has good selectivity and anti-interference for Lys and Arg. The synthesized probe TPT has been successfully used for the precise detection of Lys and Arg in drugs and for fluorescence imaging of living cells. This work demonstrates that terphenyl-based derivatives are promising organic probes for the detection of Lys and Arg, providing a new way for designing other amino acids probes.

Facile Synthesis of Core-Shell Magnetic Iron Oxide@SiO2-NH2 Nanoparticles and Their Application in Rapid Boron Removal from Aqueous Solutions

In this study, amino-functionalized magnetic particles (iron oxide@SiO2-NH2) with core-shell structures were synthesized and evaluated for rapid boron removal from aqueous solutions. The results showed that the specific surface area of the iron oxide@SiO2-NH2 (131.24 m2⋅g−1) increased greatly compared to pure iron oxide (30.98 m2⋅g−1). The adsorption equilibrium was less than 2 h, with an adsorption capacity of 29.76 mg⋅g−1 at pH = 6 at 15 °C. The quasi-second-order kinetic model described the boron adsorption process well, and both the Langmuir and Freundlich models were suitable for characterizing the adsorption isotherms. The zeta potential and XPS analysis before and after adsorption revealed that the main adsorption mechanism was the hydrogen bonding formation between the terminal -NH2 groups of the adsorbent and the boric acid. In addition, the adsorbent still maintained a high adsorption performance after five adsorption–desorption cycles, which illustrated that the iron oxide@SiO2-NH2 may be a potential adsorbent for environmental boron removal treatment.

Two Stable Pillar-Layered Zn-LMOFs for Highly Fluorescence Sensing of Inorganic Pollutants and Nitro Aromatic Compounds in Water.

Luminescent metal-organic frameworks (LMOFs) are a potential class of functional materials for the photoluminescent detection of a wide range of analytes as well as for the detection of pollutants in wastewater. Herein, by using the pillar-layered strategy, two new luminescence Zn-LMOFs (JLU-MOF222 and JLU-MOF223) were successfully solvothermal synthesized. The 2D layers are both consisting of Zn2+ and TPHC [TPHC = (1,1':2',1″-terphenyl)-3,3″,4,4',4″,5'-hexacarboxylic acid] ligands and then pillared by the different N-donor ligands to form the 3D Zn-LMOFs with fsh topology. Benefiting from the uncoordinated carboxylate sites, uncoordinated N atom, or -NH2 group in the pillaring ligands and excellent stability in pH = 2-13 aqueous phase, JLU-MOF222 and JLU-MOF223 not only can sensitively detect trace amounts of inorganic pollutants (Fe3+, Cr2O72-) and nitro aromatic compounds TNP and 2,4-DNP (TNP = 2,4,6- trinitrophenol, 2,4-DNP = 2,4-dinitrophenol) through luminescence quenching but also exhibit high selectivity of other anti-interference competing analytes. The two new Zn-LMOFs can be used as potential luminescent sensors for pollutant detection in water due to their high KSV and low limit of detection (LOD).

Effect of Solvent on the Optical Rotation of Azatryptophan Derivatives.

Chirally pure enantiomers of differently protected 7-azatryptophan derivatives (R-3c, S-3c, R-3i, S-3i, R-3m, S-3m, R-3aa, and S-3aa) were synthesized, which showed solvent-dependent optical rotation. The obtained results not only exhibited changes in the values but also showed the variation in sign (- or +) with the different solvents studied. The change in optical rotation value was essentially attributed to the electron-donating property, which can be correlated to the donor number of the solvents. There are two types of hydrogen bonds, intramolecular (i.e., form within the structure) and intermolecular (i.e., form with external groups such as solvents). These hydrogen bonds are responsible for the value and sign variations, and 1H NMR experiments were used to further characterize them. The NMR data suggested that hydrogen bond formation is occurring between the Fmoc NH group vicinal to the chiral center and donor group of the corresponding solvent.

Isoniazid-historical development, metabolism associated toxicity and a perspective on its pharmacological improvement.

Despite the extraordinary anti-tubercular activity of isoniazid (INH), the drug-induced hepatotoxicity and peripheral neuropathy pose a significant challenge to its wider clinical use. The primary cause of INH-induced hepatotoxicity is in vivo metabolism involving biotransformation on its terminal -NH2 group owing to its high nucleophilic nature. The human N-acetyltransferase-2 enzyme (NAT-2) exploits the reactivity of INH's terminal -NH2 functional group and inactivates it by transferring the acetyl group, which subsequently converts to toxic metabolites. This -NH2 group also tends to react with vital endogenous molecules such as pyridoxine, leading to their deficiency, a major cause of peripheral neuropathy. The elevation of liver functional markers is observed in 10%-20% of subjects on INH treatment. INH-induced risk of fatal hepatitis is about 0.05%-1%. The incidence of peripheral neuropathy is 2%-6.5%. In this review, we discuss the genesis and historical development of INH, and different reported mechanisms of action of INH. This is followed by a brief review of various clinical trials in chronological order, highlighting treatment-associated adverse events and their occurrence rates, including details such as geographical location, number of subjects, dosing concentration, and regimen used in these clinical studies. Further, we elaborated on various known metabolic transformations highlighting the involvement of the terminal -NH2 group of INH and corresponding host enzymes, the structure of different metabolites/conjugates, and their association with hepatotoxicity or neuritis. Post this deliberation, we propose a hydrolysable chemical derivatives-based approach as a way forward to restrict this metabolism.

Revealing Defect Passivation and Charge Extraction by Ultrafast Spectroscopy in Perovskite Solar Cells through a Multifunctional Lewis Base Additive Approach

Defect passivation inside the crystal lattice and the grain‐boundary (GB) surface of the perovskite films has become the most effective strategy to suppress the negative impact of the nonradiative recombination in perovskite solar cell. In this study, a unique approach to effectively passivate the defect states of MAPbI3 perovskite thin film using thionicotinamide (TNM) as a multifunctional Lewis base additive is demonstrated. TNM as an additive with three different types of Lewis base sites, i.e., pyridine, amino, and CS functional groups, is introduced to mitigate the trap states in the TNM‐modified perovskite films and thoroughly investigate the passivation defects. The nonbonded electron of the three different Lewis base sites can synergistically passivate the antisite lead (Pb) defects and improve the stability of the device. In addition, the NH2 group can form ionic bonds with negatively charged I– ions and inhibit ion migration caused by them. It is found that such passivation effect of TNM reduces the GB defects and improves the crystallinity significantly. As a result, a champion TNM‐modified device shows an improved power conversion efficiency of 19.26% from 16.86% along with enhanced open‐circuit voltage, fill factor, and negligible hysteresis.

Mechanism for airborne ozone decomposition on X-MIL-53(Fe) (X = H, NH2, NO2)

Ground−level ozone (O3) pollution poses a significant threat to both ecosystem sustainability and human health. The catalytic decomposition of O3 presents as a promising technology to address the issues of O3 pollution. This study undertook the synthesis of various functionalized metal−organic framework (MOF) catalysts (i.e., X-MIL-53(Fe) (X = H, NH2, NO3)) to delve into the influence of ligand functional groups on skeletal structure and catalytic efficacy, particularly focusing on unraveling the mechanism of O3 catalytic decomposition under humid conditions. NH2-MIL-53(Fe) catalyst achieved complete O3 decomposition under ambient temperature and high humidity conditions (RH=75 %), exhibiting a reaction rates (mol·m−2·s−1) 129 and 10.5 times greater than that of MIL-53(Fe) and NO2-MIL-53(Fe). The NH2 group promotes electron flow within the backbone towards the hydroxyl group (OH) linked to Fe atom. In humid O3, H2O molecules augment the interaction between O3 and NH2-MIL-53(Fe), and OH is converted to·O2− after deprotonation, promoting O3 decomposition. Additionally, leveraging three−dimensional (3D) printing technology, a monolithic catalyst for O3 decomposition was prepared for application. This study not only advances understanding of the mechanisms underlying O3 decomposition but also offers practical solutions for addressing O3 pollution at humid conditions.

The Influence of Reorientational and Vibrational Dynamics on the Mg2+ Conductivity in Mg(BH4)2·CH3NH2.

Reorientational dynamics in solid electrolytes can significantly enhance the ionic conductivity, and understanding these dynamics can facilitate the rational design of improved solid electrolytes. Additionally, recent investigations on metal hydridoborate-based solid electrolytes have shown that the addition of a neutral ligand can also have a positive effect on the ionic conductivity. In this study, we investigate the dynamics in monomethylamine magnesium borohydride (Mg(BH4)2·CH3NH2) with quasielastic and inelastic neutron scattering, density functional theory calculations, and molecular dynamics simulations. The results suggest that the addition of methylamine significantly speeds up the reorientational frequency of the BH4 - anion compared to Mg(BH4)2. This is likely part of the explanation for the high Mg-ion transport observed for Mg(BH4)2·CH3NH2. Furthermore, while the dynamics of both the BH4 - anion and the CH3 group of the methylamine ligand is rapid, the NH2 group of the methylamine ligand exhibits much slower reorientations, as confirmed by both experimental and computational investigations. Notably, molecular dynamics calculations reveal mean square displacements of 0.387 Å2 for NH2, 1.503 Å2 for CH3, and 1.856 Å2 for BH4 - using a trajectory of 10 ps. This study confirms the simultaneous presence of fast dynamics and high ionic conductivity in a metal borohydride-based system and can function as an experimental foundation for future studies on dynamics in hydrogen-rich solid electrolytes.

Tailoring the local catalytic microenvironment of metal centers NH2 groups to enhance the CO2RR performance of Ni based catalysts

Efficient catalytic reduction of the main greenhouse gas CO2 into high value-added chemicals is an important measure to alleviate the greenhouse effect and energy depletion. Metal nitrogen (M-N4) macrocyclic complexes have attracted increasing attention in the field of electrocatalytic CO2 reduction (CO2RR) due to the precise adjustment of the catalytic active site according to the requirements and the flexible modification of the external ligand structure. Nevertheless, the poor activity and low selectivity of reduction products restrict their widespread application in electrocatalytic CO2RR. Herein, a combination of nanoscale and molecular level method has been developed to construct easily obtainable 4NH2-NiPc/NH2-CNT hybrid material, in which amino groups are connected to provide electrons toward the central Ni-N4 site to promote the electrocatalytic CO2RR catalytic activity. As a result, the catalyst 4NH2-NiPc/NH2-CNT mainly produces CO in the electrocatalytic CO2RR, which exhibits a Faradaic efficiency of CO (FECO) higher than 92 % within a wide overpotential range of −0.70 to −0.95 V vs. RHE, and provides excellent stability with a current density of 12 mA cm−2 at −0.80 V vs. RHE. In addition, 4NH2-NiPc/NH2-CNT reaches its maximum FECO value of 96 % at −0.8 V vs. RHE, which is approximately 3.1 times that of the original unmodified NiPc/CNT, demonstrating excellent promotion of electrochemical performance. Similarly, compared to NiPc/CNT without amino modification, the current density of 4NH2-NiPc/NH2-CNT exceeds it by more than twice. The research results indicate that promoting role of electron substituted amino groups in catalysis dispersion and electronic environment coordination. This study proposes a promising strategy of introducing amino groups into molecular catalysts and hybridizing with carbon nanotube to enhance the electrocatalytic conversion of CO2 to deep reduction products.