RESUMEN
Pesticides are vital for ensuring crop protection and stable yields, but their low efficiency and eco-unfriendly carriers raise environmental concerns. In this study, abamectin nanopesticides were designed and fabricated using natural polysaccharides [gum arabic (GA)] and a co-stabiliser via flash nanoprecipitation (FNP) method to reduce the size of nanopesticides and enhance their foliar affinity and deposition. Various co-stabilisers were innovatively introduced into the FNP process; the synergy between GA and the co-stabiliser significantly reduced the particle size (111.5 nm), narrowed the size distribution (polydispersity index = 0.078), and enhanced the stability and release performance of the nanopesticides. Importantly, the downsized nanopesticides effectively improved retention on leaf surfaces, reducing pesticide loss. In addition, because of the excellent control capability of the FNP method, the particle size of the nanopesticides could be flexibly adjusted by modifying the flow-based process parameters. Nanopesticides with small sizes demonstrated good control efficacy against Tetranychus urticae, comparable to those of commercial emulsion in water formulations. This study provides an effective approach for enhancing the utilisation efficiency of pesticide droplets by reducing particle size to ensure sustainable agriculture.
RESUMEN
Herein, by replacement of the linear terephthalate linker with the bending 2,5-thiophenedicarboxylate (tdc2-) linker in the typical (3,9)-connected metal-organic framework, with a reduced 8-connected hydroxyl-centered trinuclear cluster, a new (3,8)-connected network, [Ni3(µ3-OH)(tdc)3(tpp)] [DZU-1; tpp = 2,4,6-tris(4-pyridyl)pyridine], was synthesized. The modified pore environment enables DZU-1 to selectively adsorb C2H2 over CO2 in an efficient manner.
RESUMEN
Ethylene production from C2 hydrocarbon mixtures through one separation step is desirable but challenging because of the similar size and physical properties of acetylene, ethylene, and ethane. Herein, we report three new isostructural porous coordination networks (NPU-1, NPU-2, NPU-3; NPU represents Northwestern Polytechnical University) that are sustained by 9-connected nodes based upon a hexanuclear metal cluster of composition [Mn6(µ3-O)2(CH3COO)3]6+. NPU-1/2/3 exhibit a dual cage structure that was systematically fine-tuned in terms of cage size to realize selective adsorption of C2H2 and C2H6 over C2H4. Dynamic breakthrough experiments demonstrated that NPU-1 produces ethylene in >99.9% purity from a three-component gas mixture (1:1:1 C2H2/C2H4/C2H6). Molecular modeling studies revealed that the dual adsorption preference for C2H2 and C2H6 over C2H4 originates from (a) strong hydrogen-bonding interactions between electronegative carboxylate O atoms and C2H2 molecules in one cage and (b) multiple non-covalent interactions between the organic linkers of the host network and C2H6 molecules in the second cage.
RESUMEN
Design and synthesis of low-cost catalysts with high activity and stability for hydrogenation reactions is an important research area of applied catalysis. In this work, we present a kind of ultrafine cobalt oxides encapsulated by N-doped carbon (donated as CoOx/CN) as efficient catalysts for hydrogenation of 4-nitrophenol (4-NP) process. The CoOx/CN was fabricated through a pyrolysis strategy using an N-containing metal-organic framework (Co-MOF) as precursor followed by a fine thermal-treatment. With an optimized pyrolysis temperature of 500⯰C, the CoOx species present as ultrafine particles highly dispersed in the obtained catalyst (CoOx/CN-500). CoOx/CN-500 exhibits excellent activity and stability in hydrogenation of 4-NP at ambient conditions. The activity is much higher than that of not only bulk cobalt oxides, but also carbon supported CoOx catalysts. It could be used for more than 8 times without obvious fading in activity. In addition, the concrete role of Co-MOF precursor and pyrolysis condition in the catalyst design was investigated in detail. The interaction between organic ligands and Co ions and the confinement of the crystalline structure of Co-MOF could restrain the aggregation of Co ions during pyrolysis and lead to high dispersion of ultrafine CoOx species. Meanwhile, the N-containing ligands could be transformed into doped N species (pyridinic and pyrrolic N), endowing the CoOx species with high electron density and promoting the formation of active sites for the hydrogenation reaction.
RESUMEN
By the solvothermal reaction of a triangular ligand, 2,4,6-tris-(4-carboxyphenoxy)-1,3,5-triazine (H3tcpt) with Zn(NO3)2·6H2O in N,N'-dimethylacetamide/acetonitrile/H2O (v/v/v = 1 : 1 : 1) mixed solvents, a two-fold, interpenetrated, three-dimensional (3D), porous metal-organic framework, [Zn2(tcpt)OH]·solvents (1·solvents), with a rare, paddlewheel secondary building unit (SBU), Zn2(COO)3, was synthesized and characterized. It was found that a single 3D structure of 1 forms when two-dimensional layers, which are constructed by tcpt(3-) bonding with the paddlewheel SBUs, are linked by -OH groups along the axial sites of the SBUs. Compared with the reported Zn(ii)-based partners with this ligand, synthesis conditions, particularly the solvents used, clearly played a key role in the formation of different SBUs, thereby resulting in distinct MOFs with the same ligand. In particular, 1 features good water and thermal stability and can withstand acidic aqueous solutions with pH values ranging from 5 to 12. In addition, 1 displays good adsorption ability towards H2 (2.21 wt% at 77 K and 1 atm) and can selectively adsorb CO2 from CH4 and N2, in spite of its relatively low void volume (36.8%), suggesting potential applications in gas storage and separation.
RESUMEN
In the title coordination compound, [Mn(2)(C(14)H(8)O(4))(C(2)O(4))(C(10)H(14)N(4))(2)](n), the biphenyl-3,3'-dicarboxyl-ate and oxalate anions, both situated on inversion centres, function in a bridging mode, linking the dinuclear Mn(II) atoms into wave-like layers. Each 1,1'-(1,4-butane-1,4-di-yl)diimidazole ligand coordinates to two Mn(II) atoms located in adjacent layers via Mn-N coordination bonds, giving a three-dimensional network. As the methyl-ene groups can bend freely relative to each other due to the C atoms connected via single bonds, the 1,1'-(butane-1,4-di-yl)diimidazole ligand forms an S-shaped conformation, which makes the void in the three-dimensional network distorted.
RESUMEN
In the title compound, C(18)H(19)NO(4)S, the two benzene rings form a dihedral angle of 52.2â (7)°. The crystal struture is stabilized by N-Hâ¯O hydrogen bonds, which link the molecules into dimers.
RESUMEN
In the title compound, C(3)H(8)N(6) (2+)·SO(4) (2-), the melaminium cations and sulfate anions are inter-connected by N-Hâ¯N and N-Hâ¯O hydrogen bonds, forming a layer in the (101) plane. The layers are connected through multiple hydrogen bonds and π-π stacking inter-actions (centroid-centroid distance of about 3.4â Å).
RESUMEN
In the centrosymmetric dinuclear complex, [Cu(2)(C(8)H(4)O(5))(2)(C(10)H(8)N(2))(2)(H(2)O)(2)], the Cu(II) ion is coordinated by two N atoms from a bipyridine ligand, three O atoms from two 3-carb-oxy-2-oxidobenzoate dianions and the O atom of the water mol-ecule in a distorted octa-hedral geometry. The Cu--O(H) coordination [2.931â (3)â Å] is very weak. In the crystal structure, the dinuclear units are linked into a two-dimensional network parallel to (010) by O-Hâ¯O hydrogen bonds.