Cross-Linking CdSO4-Type Nets with Hexafluorosilicate Anions to Form an Ultramicroporous Material for Efficient C2H2/CO2 and C2H2/C2H4 Separation.

A 44.610.8 topology hybrid ultramicroporous material (HUM), {[Cu1.5F(SiF6)(L)2.5]·G}n, (L = 4,4'-bisimidazolylbiphenyl, G = guest molecules), 1, formed by cross-linking interpenetrated 3D four-connected CdSO4-type nets with hexafluorosilicate anions is synthesized and evaluated in the context of gas sorption and separation herein. 1 is the first HUM functionalized with two different types of fluorinated sites (SiF6 2- and F- anions) lining along the pore surface. The optimal pore size (≈5 Å) combining mixed and high-density electronegative fluorinated sites enable 1 to preferentially adsorb C2H2 over CO2 and C2H4 by hydrogen bonding interactions with a high C2H2 isosteric heat of adsorption (Qst) of ≈42.3 kJ mol-1 at zero loading. The pronounced discriminatory sorption behaviors lead to excellent separation performance for C2H2/CO2 and C2H2/C2H4 that surpasses many well-known sorbents. Dynamic breakthrough experiments are conducted to confirm the practical separation capability of 1, which reveal an impressive separation factor of 6.1 for equimolar C2H2/CO2 mixture. Furthermore, molecular simulation and density functional theory (DFT) calculations validate the strong binding of C2H2 stems from the chelating fix of C2H2 between SiF6 2- anion and coordinated F- anion.

Hydroamination of Triisopropylsilyl Acetylene Sulfur Pentafluoride - a Bench-top Route to Pentafluorosulfanylated Enamines.

Synthetic access to a variety of aliphatic and vinylic pentafluorosulfanylated building blocks remains a major challenge in contemporary organofluorine chemistry hampering its investigation in the context of medicinal chemistry, agrochemistry and functional materials. Herein, we report a bench-top protocol to access the virtually unknown class of α-SF5 -enamines under mild reaction conditions in good to excellent yields (up to 95 %). This reaction combines the protodesilylation of the commercially available precursor TASP with the in situ hydroamination of HC≡C-SF5 . The on-site use of highly toxic gases or corrosive reagents is avoided, making access to this motif applicable to a wide chemical audience. The excellent E-diastereoselectivity of this two-step cascade reaction is suggested to be the result of the convergence of the fast Z-/E- isomerization of a vinyl anion as well as the isomerization of the iminium ion. The remarkable thermal stability of these SF5 -enamines encourages further studies of their synthetic utility.

Ca(II) and Yb(II) complexes featuring M(C≡C)4 structural motif: enforced proximity or genuine η2 -bonding?

Bis(carbazolide) complexes M[3,6-tBu2 -1,8-(RC≡C)2 Carb]2 (THF)n (R=SiMe3 , n=0, M=Ca, Yb; R=Ph, n=1, M=Ca, Yb; n=0, M=Yb) were synthesized through transamination reaction of M[N(SiMe3 )2 ]2 (THF)2 with two molar equivalents of carbazoles. The complexes feature M(η2 -C≡C)4 structural motif composed of M(II) ions encapsulated by four acetylene fragments due to atypical for alkaline- and rare-earth metals η2 -interactions with triple C≡C bond. This interaction is evidenced experimentally by X-ray diffraction, Raman spectroscopy in the solid state and by NMR-spectroscopy in the solution. According to QTAIM analysis there are 4 bond critical points (3;-1) between the metal atom and each of the triple bonds, which are connected by a strongly curved, almost T-shaped bond pathway.

Mono(Lewis Base)-Stabilized Gallium Iodide: An Unexplored Class of Promising Ligands.

Quantum-chemical (DFT) calculations on hitherto unknown base(carbene)-stabilized gallium monoiodides (LB→GaI) suggest that these systems feature one lone pair of electrons and a formally vacant p-orbital - both centered at the central gallium atom - and exhibit metallomimetic behavior. The calculated reaction free energies as well as bond dissociation energies suggest that these LB→GaI systems are capable of forming stable donor-acceptor complexes with group 13 trichlorides. Examination of the ligand exchange reactions with iron and nickel complexes indicates their potential use as ligands in transition metal chemistry. In addition, it is found that the title compounds are also able to activate various enthalpically robust bonds. Further, a detailed mechanistic investigation of these small molecule activation processes reveals the non-innocent behavior of the carbene (base) moiety attached to the GaI fragment, thereby indicating the cooperative nature of these bond activation processes. The energy decomposition analysis (EDA) and activation strain model (ASM) of reactivity were also employed to quantitatively understand and rationalize the different activation processes.

Co/SiO2 Catalyst for Methoxycarbonylation of Acetylene: On Catalytic Performance and Active Species.

Reppe carbonylation of acetylene is an atom-economic and non-petroleum approach to synthesize acrylic acid and acrylate esters, which are key intermediates in the textile, leather finishing, and polymer industries. In the present work, a noble metal-free Co@SiO2 catalyst was prepared and evaluated in the methoxycarbonylation reaction of acetylene. It was discovered that pretreatment of the catalyst by different reductants (i.e., C2H2, CO, H2, and syngas) greatly improved the catalytic activity, of which Co/SiO2-H2 demonstrated the best performance under conditions of 160 °C, 0.05 MPa C2H2, 4 MPa CO, and 1 h, affording a production rate of 4.38 gMA+MP gcat-1 h-1 for methyl acrylate (MA) and methyl propionate (MP) and 0.91 gDMS gcat-1 h-1 for dimethyl succinate (DMS), respectively. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and diffuse reflectance infrared Fourier transform spectra of CO adsorption (CO-DRIFTS) measurements revealed that an H2 reduction decreased the size of the Co nanoparticles and promoted the formation of hollow architectures, leading to an increase in the metal surface area and CO adsorption on the catalyst. The hot filtration experiment confirmed that Co2(CO)8 was generated in situ during the reaction or at the pre-activation stage, which served as the genuine active species. Our work provides a facile and convenient approach to the in situ synthetization of Co2(CO)8 for a Reppe carbonylation reaction.

Reactivity of the Ethenium Cation (C2H5+) with Ethyne (C2H2): A Combined Experimental and Theoretical Study.

The gas-phase reaction between the ethyl cation (C2H5+) and ethyne (C2H2) is re-investigated by measuring absolute reactive cross sections (CSs) and branching ratios (BRs) as a function of collision energy, in the thermal and hyperthermal energy range, via tandem-guided ion beam mass spectrometry under single collision conditions. Dissociative photoionization of C2H5Br using tuneable VUV radiation in the range 10.5-14.0 eV is employed to generate C2H5+, which has also allowed us to explore the impact of increasing (vibrational) excitation on the reactivity. Reactivity experiments are complemented by theoretical calculations, at the G4 level of theory, of the relative energies and structures of the most relevant stationary points on the reactive potential energy hypersurface (PES) and by mass-analyzed ion kinetic energy (MIKE) spectrometry experiments to probe the metastable decomposition from the [C4H7]+ PES and elucidate the underlying reaction mechanisms. Two main product channels have been identified at a centre-of-mass collision energy of ∼0.1 eV: (a) C3H3++CH4, with BR = 0.76±0.05 and (b) C4H5++H2, with BR = 0.22±0.02. A third channel giving C2H3+ in association with C2H4 is shown to emerge at both high internal excitation of C2H5+ and high collision energies. From CS measurements, energy-dependent total rate constants in the range 4.3×10-11-5.2×10-10 cm3·molecule-1·s-1 have been obtained. Theoretical calculations indicate that both channels stem from a common covalently bound intermediate, CH3CH2CHCH+, from which barrierless and exothermic pathways exist for the production of both cyclic c-C3H3+ and linear H2CCCH+ isomers of the main product channel. For the minor C4H5+ product, two isomers are energetically accessible: the three-member cyclic isomer c-C3H2(CH3)+ and the higher energy linear structure CH2CHCCH2+, but their formation requires multiple isomerization steps and passages via transition states lying only 0.11 eV below the reagents' energy, thus explaining the smaller BR. Results have implications for the modeling of hydrocarbon chemistry in the interstellar medium and the atmospheres of planets and satellites as well as in laboratory plasmas (e.g., plasma-enhanced chemical vapor deposition of carbon nanotubes and diamond-like carbon films).

[Liver impairment status toward workers exposed to vinyl chloride under different techniques].

OBJECTIVE: To analyse potential differences towards liver impairment status on vinyl chloride monomer(VCM) exposed population from technique under acetylene hydrochlorination to the one of ethylene oxychlorination respectively and to explore the possible reasons, which will pave the way for occupational health promotion in terms of hazard reduction. METHODS: a cross-sectional study was initiated between June and September in 2022 towards 2 groups of VCM exposed population from the facility of acetylene hydrochlorination(n=78) and the one of ethylene oxychlorination(n=69) in a PVC petrochemical complex enterprise(abbreviation of H) in Tianjin City. The demographic information concerning age, gender, messages on occupational history, field investigation were inquired through questionnaire interview. Then, venous blood(4 mL/person) and urine(10-50 mL/person) were collected during the physical exam phase and indices of 8-hydroxy-2 deoxyguanosine(8-OHdG) in blood and thiodiglycolic acid(TDGA) in urine were detected through ELISA and solid phase extraction-ion chromatography respectively. RESULTS: The 2 groups of population were matched well in terms of average age distribution and gender composition ratio, with significant differences on population composition ratio were found on variables of working years, alcohol consumption and daily sleeping duration(P<0.01 or P<0.05). It was found that the average content of TDGA in acetylene hydrochlorination group was(0.81±0.05)mg/L while the content in ethylene oxychlorination group reached to(0.83±0.06)mg/L, noteworthy differences were only found among 6 posts in the acetylene hydrochlorination group and 5 others in the ethylene oxychlorination group after classification for specific posts, however, the average concentration of 8-OHdG in acetylene hydrochlorination group(122(78.3, 168.8) µg/m~3) was different from the one in ethylene oxychlorination group(101.7(79.6, 149.7) µg/m~3)(Z=6.82, P<0.05). Moreover, a series of positive correlations in moderate intensity between 8-OHdG concentration and TDGA content were observed among posts of polymerization cleaners(r=0.53), aggregation operators(r=0.47), maintenance repairers(r=0.45), sampling operators(r=0.41) in acetylene hydrochlorination group(P<0.05) and posts of cracking reactants(r=0.64), DCS operators(r=0.51), oxychlorination operators(r=0.50) and chemical loaders(r=0.44) in ethylene oxychlorination group(P<0.05). Liver function indices such as content on ALT(χ~2=15.41, P<0.01), AST(χ~2=9.95, P<0.01) and ALP(χ~2=3.79, P<0.01) were different in the 2 groups population with statistical significance, then proportions on population composition ratio that exceeded normal ranges of indices on ALT, AST, AST/ALT ratio, ALP and Alb/Glb ratio were higher in acetylene hydrochlorination group than ones in ethylene oxychlorination group with great significance(P<0.05), so as to the abnormalities in liver B altrosonography test between groups(χ~2=17.33, P<0.01). Binary logistic regression model indicated that 8-OHdG concentration in blood that exceed 90 µg/m~3, TDGA content in urine that exceed 0.60 mg/L, working years that were over 10a, alcohol consumption, sleeping duration less than 6 h per day and male workers were potential risky factors for liver impairment(P<0.05). CONCLUSION: The degree on liver impairment status was higher in acetylene hydrochlorination group than ones in in ethylene oxychlorination group under the same PVC factory, which might be associated with the oxidative stress injury induced from the combination of higher VCM concentration at workplaces, longer cumulative exposure time, longer working years, alcohol consumption habits and sleep shortage caused by shift work patterns.

Modular and Diverse Synthesis of Acrylamides by Palladium-Catalyzed Hydroaminocarbonylation of Acetylene.

The development of all kinds of covalent drugs had a major impact on the improvement of the human health system. Covalent binding to target proteins is achieved by so-called electrophilic warheads, which are incorporated in the respective drug molecule. In the last decade, specifically acrylamides emerged as attractive warheads in covalent drug design. Herein, a straightforward palladium-catalyzed hydroaminocarbonylation of acetylene has been developed, allowing a modular and diverse synthesis of bio-active acrylamides. This general protocol features high atom efficiency, wide functional group compatibility, high chemoselectivity and proceeds additive free under mild reaction conditions. The synthetic utility of this protocol is showcased in the synthesis of ibrutinib, osimertinib, and other bio-active compound derivatives.

Electrocatalytic Acetylene Hydrogenation in Concentrated Seawater at Industrial Current Densities.

Electrocatalytic acetylene hydrogenation to ethylene (E-AHE) is a promising alternative for thermal-catalytic process, yet it suffers from low current densities and efficiency. Here, we achieved a 71.2 % Faradaic efficiency (FE) of E-AHE at a large partial current density of 1.0 A cm-2 using concentrated seawater as an electrolyte, which can be recycled from the brine waste (0.96 M NaCl) of alkaline seawater electrolysis (ASE). Mechanistic studies unveiled that cation of concentrated seawater dynamically prompted unsaturated interfacial water dissociation to provide protons for enhanced E-AHE. As a result, compared with freshwater, a twofold increase of FE of E-AHE was achieved on concentrated seawater-based electrolysis. We also demonstrated an integrated system of ASE and E-AHE for hydrogen and ethylene production, in which the obtained brine output from ASE was directly fed into E-AHE process without any further treatment for continuously cyclic operations. This innovative system delivered outstanding FE and selectivity of ethylene surpassed 97.0 % and 97.5 % across wide-industrial current density range (≤ 0.6 A cm-2), respectively. This work provides a significant advance of electrocatalytic ethylene production coupling with brine refining of seawater electrolysis.

Enantioselective Allylboration of Acetylene: A Versatile Tool for the Stereodivergent Synthesis of Natural Products.

Efficient catalytic methods that allow the use of simple and abundant chemical feedstocks for the preparation of synthetically versatile compounds are central to modern synthetic chemistry. Acetylene is a basic feedstock with a remarkable production over one million tons per year, although it is underutilized in the stereoselective synthesis of fine chemicals. Here we report a facile catalytic multicomponent reaction that allows for the enantio- and diastereoselective allylboration of acetylene gas. This process is catalyzed by a chiral copper catalyst, operates without specialized equipment or pressurization, and provides chiral skipped dienes bearing stereodefined and orthogonally functionalized olefins with excellent levels of chemo-, regio-, enantio- and diastereoselectivity. The combined stereochemical features and orthogonal functionalization make the products privileged structural scaffolds to access the complete set of stereoisomers of the chiral skipped diene core through simple enantio- and diastereodivergent pathways. The utility of the method is demonstrated with the enantioselective synthesis of three bioactive natural skipped diene products, namely (+)-Nyasol, (+)-Hinokiresinol and Phorbasin C, and other related synthetically relevant chiral molecules.

Reverse Separation of Carbon Dioxide and Acetylene in Two Isostructural Copper Pyridine-Carboxylate Frameworks.

Separating acetylene from carbon dioxide is important but highly challenging due to their similar molecular shapes and physical properties. Adsorptive separation of carbon dioxide from acetylene can directly produce pure acetylene but is hardly realized because of relatively polarizable acetylene binds more strongly. Here, we reverse the CO2 and C2H2 separation by adjusting the pore structures in two isoreticular ultramicroporous metal-organic frameworks (MOFs). Under ambient conditions, copper isonicotinate (Cu(ina)2), with relatively large pore channels shows C2H2-selective adsorption with a C2H2/CO2 selectivity of 3.4, whereas its smaller-pore analogue, copper quinoline-5-carboxylate (Cu(Qc)2) shows an inverse CO2/C2H2 selectivity of 5.6. Cu(Qc)2 shows compact pore space that well matches the optimal orientation of CO2 but is not compatible for C2H2. Neutron powder diffraction experiments confirmed that CO2 molecules adopt preferential orientation along the pore channels during adsorption binding, whereas C2H2 molecules bind in an opposite fashion with distorted configurations due to their opposite quadrupole moments. Dynamic breakthrough experiments have validated the separation performance of Cu(Qc)2 for CO2/C2H2 separation.

Achieving Record C2H2 Packing Density for Highly Efficient C2H2/C2H4 Separation with a Metal-Organic Framework Prepared by a Scalable Synthesis in Water.

Adsorptive C2H2/C2H4 separation using metal-organic frameworks (MOFs) has emerged as a promising technology for the removal of C2H2 (acetylene) impurity (1%) from C2H4 (ethylene). The practical application of these materials involves the optimization of separation performance as well as development of scalable and green production protocols.Herein, we report the efficient C2H2/C2H4 separation in a MOF, Cu(OH)INA (INA: isonicotinate) which achieves a record C2H2 packing density of 351 mg cm-3 at 0.01 bar through high affinity towards C2H2. DFT (density functional theory) calculations reveal the synergistic binding mechanism through pore confinement and the oxygen sites in pore wall.The weakly basic nature of binding sites leads to a relatively low heat of adsorption (Qst) of approximately 36 kJ/mol, which is beneficial for material regeneration and thermal management. Furthermore, a scalable and environmentally friendly synthesis protocol with a high space-time yield of 544 kg m-3 day-1 has been developed without using any modulating agents. This material also demonstrates enduring separation performance for multiple cycles, maintaining its efficacy after exposure to water or air for three months.

Asymmetric Coupled Binuclear-Site Catalysts for Low-Temperature Selective Acetylene Semi-hydrogenation.

Heterogeneous metal catalysts with bifunctional active sites are widely used in chemical industries. Although their improvement process is typically based on trial-and-error, it is hindered by the lack of model catalysts. Herein, we report an effective vacancy-pair capturing strategy to fabricate 12 heterogeneous binuclear-site catalysts (HBSCs) comprising combinations of transition metals on titania. During the synthesis of these HBSCs, proton-passivation treatment and step-by-step electrostatic anchorage enabled the suppression of single-atom formation and the successive capture of two target metal cations on the titanium-oxygen vacancy-pair site. Additionally, during acetylene hydrogenation at 20 °C, the HBSCs (e.g., Pt1Pd1-TiO2) consistently generated more than two times the ethylene produced by their single-atom counterparts (e.g., Pd1-TiO2). Furthermore, the Pt1Pd1 binuclear sites in Pt1Pd1-TiO2 were demonstrated to catalyze C2H2 hydrogenation via a bifunctional active-site mechanism: initially C2H2 chemisorb on the Pt1 site, then H2 dissociates and migrates from Pd1 to Pt1, and finally hydrogenation occurs at the Pt1-Pd1 interface.

Highly Selective Acetylene-to-Ethylene Electroreduction Over Cd-Decorated Cu Catalyst with Efficiently Inhibited Carbon-Carbon Coupling.

Electrochemical acetylene reduction (EAR) employing Cu catalysts represents an environmentally friendly and cost-effective method for ethylene production and purification. However, Cu-based catalysts encounter product selectivity issues stemming from carbon-carbon coupling and other side reactions. We explored the use of secondary metals to modify Cu-based catalysts and identified Cd decoration as particular effective. Cd decoration demonstrated a high ethylene Faradaic efficiency (FE) of 98.38 % with well-inhibited carbon-carbon coupling reactions (0.06 % for butadiene FE at -0.5 V versus reversible hydrogen electrode) in a 5 vol % acetylene gas feed. Notably, ethylene selectivity of 99.99 % was achieved in the crude ethylene feed during prolonged stability tests. Theoretical calculations revealed that Cd metal accelerates the water dissociation on neighboring Cu surfaces allowing more H* to participate in the acetylene semi-hydrogenation, while increasing the energy barrier for carbon-carbon coupling, thereby contributing to a high ethylene semi-hydrogenation efficiency and significant inhibition of carbon-carbon coupling. This study provides a paradigm for a deeper understanding of secondary metals in regulating the product selectivity of EAR electrocatalysts.

A Gold(I)-Acetylene Complex Synthesised using Single-Crystal Reactivity.

Using single-crystal to single-crystal solid/gas reactivity the gold(I) acetylene complex [Au(L1)(η2-HC≡CH)][BArF 4] is cleanly synthesized by addition of acetylene gas to single crystals of [Au(L1)(CO)][BArF 4] [L1=tris-2-(4,4'-di-tert-butylbiphenyl)phosphine, ArF=3,5-(CF3)2C6H3]. This simplest gold-alkyne complex has been characterized by single crystal X-ray diffraction, solution and solid-state NMR spectroscopy and periodic DFT. Bonding of HC≡CH with [Au(L1)]+ comprises both σ-donation and π-backdonation with additional dispersion interactions within the cavity-shaped phosphine.

Discriminatory Gate-Opening Effect in a Flexible Metal-Organic Framework for Inverse CO2 /C2 H2 Separation.

Considering the significant application of acetylene (C2 H2 ) in the manufacturing and petrochemical industries, the selective capture of impurity carbon dioxide (CO2 ) is a crucial task and an enduring challenge. Here, a flexible metal-organic framework (Zn-DPNA) accompanied by a conformation change of the Me2 NH2 + ions in the framework is reported. The solvate-free framework provides a stepped adsorption isotherm and large hysteresis for C2 H2 , but type-I adsorption for CO2 . Owing to their uptakes difference before gate-opening pressure, Zn-DPNA demonstrated favorable inverse CO2 /C2 H2 separation. According to molecular simulation, the higher adsorption enthalpy of CO2 (43.1 kJ mol-1 ) is due to strong electrostatic interactions with Me2 NH2 + ions, which lock the hydrogen-bond network and narrow pores. Furthermore, the density contours and electrostatic potential verifies the middle of the cage in the large pore favors C2 H2 and repels CO2 , leading to the expansion of the narrow pore and further diffusion of C2 H2 . These results provide a new strategy that optimizes the desired dynamic behavior for one-step purification of C2 H2 .

Electroactive Dyes Based on 1,8-Naphthalimide with Acetylene Linkers as Promising OLED Materials - the Relationship Between Structure and Photophysical Properties.

Four A-π-D-π-A type small organic molecules with 1,8-naphthalimide motifs were successfully synthesised. The designed compounds are built of two 1,8-naphthalimide units linked via ethynyl π-linkages with selected functionalised donor motifs i. e. 2,2'-bithiophene, fluorene, phenothiazine and carbazole derivative. The synthesis based on Sonogashira cross-coupling allowed us to obtain the presented dyes with good yields. The resulting symmetrical small molecules' optical, electrochemical and thermal properties were thoroughly investigated, and their potential applicability for the OLED devices was demonstrated. In addition, the relationship between molecular structure and properties was considered by employing experimental and theoretical studies. As a result of using various donor groups, it was possible to achieve efficient electroluminescence in the range from green (DEV4) to orange-red light (DEV3) with a maximum luminance of 3 820 cd/m2 for DEV4. Upon the insertion of an acetylene linker to the designed molecules, the free rotation of D and A fragments, and hence the effective π-electron communication within the entire molecule, is possible, which was confirmed by DFT studies. The obtained dyes are characterised by high thermal stability, reversible oxidation-reduction process, satisfactory optoelectronic properties and good solubility in organic solvents, which is advisable for the application in small molecular organic light-emitting diodes (SM-OLEDs) technology.

Concurrent Enhancement of Acetylene Uptake Capacity and Selectivity by Progressive Core Expansion and Extra-Framework Anions in Pore-Space-Partitioned Metal-Organic Frameworks.

A multi-stage core-expansion method is proposed here as one component of the integrative binding-site/extender/core-expansion (BEC) strategy. The conceptual deconstruction of the partitioning ligand into three editable parts draws our focus onto progressive core expansion and allows the optimization of both acetylene uptake and selectivity. The effectiveness of this strategy is shown through a family of eight cationic pore-partitioned materials containing three different partitioning ligands and various counter anions. The optimized structure, Co3 -cpt-tph-Cl (Hcpt=4-(p-carboxyphenyl)-1,2,4-triazole, H-tph=(2,5,8-tri-(4-pyridyl)-1,3,4,6,7,9-hexaazaphenalene) with the largest surface area and highest C2 H2 uptake capacity (200 cm3 /g at 298 K), also exhibits (desirably) the lowest CO2 uptake and hence the highest C2 H2 /CO2 selectivity. The successful boost in both C2 H2 capacity and IAST selectivity allows Co3 -cpt-tph-Cl to rank among the best crystalline porous materials, ionic MOFs in particular, for C2 H2 uptake and C2 H2 /CO2 experimental breakthrough separation.

Acetylene Semi-Hydrogenation at Room Temperature over Pd-Zn Nanocatalyst.

A reaction of fundamental and commercial importance is acetylene semi-hydrogenation. Acetylene impurity in the ethylene feedstock used in the polyethylene industry poisons the Ziegler-Natta catalyst which adversely affects the polymer quality. Pd based catalysts are most often employed for converting acetylene into the main reactant, ethylene, however, it often involves a tradeoff between the conversion and the selectivity and generally requires high temperatures. In this work, bimetallic Pd-Zn nanoparticles capped by hexadecylamine (HDA) have been synthesized by co-digestive ripening of Pd and Zn nanoparticles and studied for semi-hydrogenation of acetylene. The catalyst showed a high selectivity of ~85 % towards ethylene with a high ethylene productivity to the tune of ~4341 µmol g-1 min-1 , at room temperature and atmospheric pressure. It also exhibited excellent stability with ethylene selectivity remaining greater than 85 % even after 70 h on stream. To the best of the authors' knowledge, this is the first report of room temperature acetylene semi-hydrogenation, with the catalyst effecting high amount of acetylene conversion to ethylene retaining excellent selectivity and stability among all the reported catalysts thus far. DFT calculations show that the disordered Pd-Zn nanocatalyst prepared by a low temperature route exhibits a change in the d-band center of Pd and Zn which in turn enhances the selectivity towards ethylene. TPD, XPS and a range of catalysis experiments provided in-depth insights into the reaction mechanism, indicating the key role of particle size, surface area, Pd-Zn interactions, and the capping agent.

Exploring potential soybean bradyrhizobia from high trehalose-accumulating soybean genotypes for improved symbiotic effectiveness in soybean.

Drought is the most important factor limiting the activity of rhizobia during N-fixation and plant growth. In the present study, we isolated Bradyrhizobium spp. from root nodules of higher trehalose-accumulating soybean genotypes and examined for moisture stress tolerance on a gradient of polyethylene glycol (PEG 6000) amended in yeast extract mannitol (YEM) broth. In addition, the bradyrhizobial strains were also evaluated for symbiotic effectiveness on soybean. Based on 16S rDNA gene sequences, four bradyrhizobial species were recovered from high trehalose-accumulating genotypes, i.e., two Bradyrhizobium liaoningense strains (accession number KX230053, KX230054) from EC 538828 and PK-472, respectively, one Bradyrhizobium daqingense (accession number KX230052) from PK-472, and one Bradyrhizobium kavangense (accession number MN197775) from Valder genotype having low trehalose. These strains, along with two native strains, viz., Bradyrhizobium japonicum (JF792425), Bradyrhizobium liaoningense (JF792426), and one commercial rhizobium, were studied for nodulation, leghaemoglobin, and N-fixation abilities on soybean under sterilized sand microcosm conditions in a completely randomized design. Among all the strains, D-4A (B. daqingense) followed by D-4B (B. liaoningense) was found to have significantly higher nodulation traits and acetylene reduction assay (ARA) activity when compared to other strains and commercial rhizobia. The bradyrhizobia isolates showed plant growth promotion traits such as indole acetic acid (IAA), exopolysaccharide (EPS), and siderophore production, phosphate-solubilizing potential, and proline accumulation. The novel species B. daqingense was reported for the first time from Indian soil and observed to be a potential candidate strain and should be evaluated for conferring drought tolerance in soybean under simulated stress conditions.