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Maxwell Hegelund posted an update 4 hours, 35 minutes ago
Liquid bridges are commonly encountered in nature and the liquid transfer induced by their rupture is widely used in various industrial applications. In this work, with the focus on the porous tip, we studied the impacts of capillary effects on the liquid transfer induced by the rupture through numerical simulations. To depict the capillary effects of a porous tip, a time scale ratio, RT, is proposed to compare the competing mechanisms of spontaneous imbibition and external drag. In terms of RT, we then develop a theoretical model for estimating the liquid retention ratio considering the geometry, porosity, and wettability of tips. The mechanism presented in this work provides a possible approach to control the liquid transfer with better accuracy in microfluidics or microfabrications.The booming of host-guest assembly-based supramolecular chemistry provides abundant ways to construct functional systems and materials. Attracted by the important application prospect of white light emission and aggregation-induced emission (AIE) materials, herein, we report an efficient way for fabricating metal-free white light-emitting AIE materials through the supramolecular assembly of simple organic compounds methoxyl pillar[5]arene (MP5) and tri-(pyridine-4-ylamido)benzene (TAP). By host-guest assembly, MP5 and TAP formed a supramolecular polymer (MP5-T); meanwhile, the MP5-T xerogel powder emitted white light at CIE coordinates (0.29 and 0.29). The supramolecular assembly and white light-emitting mechanisms were carefully investigated by experiments as well as quantum chemical calculations including density functional theory (DFT), reduced density gradient, electrostatic surface potential, independent gradient model, and frontier molecular orbital (highest-occupied molecular orbital-lowest-unoccupied molecular orbital) analyses. Interestingly, according to the experiments and calculations, the supramolecular assembly is critical in the white light-emitting phenomenon. Moreover, in this work, the quantum chemical calculations could not only support experimental phenomena but also provide deep understanding and visualized presentation of the assembly and emission mechanism. In addition, the obtained MP5-T solid powder could serve as a novel and easy means to make material for white light-emitting devices.Here, we describe three types of rearrangement reactions of sulfur ylide derived from diazoquinones and allyl/propargyl sulfides. With Rh2(esp)2 as the catalyst, diazoquinones react with allyl/propargyl sulfides to form a sulfur ylide, which undergoes a chemoselective tautomerization/[2,3]-sigmatropic rearrangement reaction, a Doyle-Kirmse rearrangement/Cope rearrangement cascade reaction, or a Doyle-Kirmse rearrangement/elimination reaction, depending on the substituent of the sulfides. The protocol provides alkenyl and allenyl sulfides and multisubstituted phenols with moderate and high yields.Asymmetric hydrogenation of 2-aryl-3-phthalimidopyridinium salts catalyzed by the Ir/SegPhos catalytic system was described, leading to the corresponding chiral piperidine derivatives bearing two contiguous chiral centers, with high levels of enantioselectivities and diastereoselectivities. A gram-scale experiment has demonstrated the utility of this approach. The phthaloyl group could be easily removed and then smoothly converted to key intermediate (+)-CP-99994 as one of the neurokinin 1 receptor antagonists.In the last two decades, titanocene monochloride has been postulated as a monoelectronic transfer reagent capable of catalyzing an important variety of chemical transformations. In this Perspective, our contributions to this growing field of research are summarized and analyzed. Especially known have been our contributions in C-C bond formation reactions, hydrogen-atom transfer from water to radicals, and isomerization reactions, as well as the development of a catalytic cycle that has subsequently allowed the preparation of a great variety of natural terpenes. It is also worth mentioning our contribution in the postulation of this single-electron transfer agent (SET) as a new green catalyst with a broad range of applications in organic and organometallic chemistry. The most significant catalytic processes developed by other research groups are also briefly described, with special emphasis on the reaction mechanisms involved. Finally, a reflection is made on the future trends in the research of this SET, aimed at consolidating this chemical as a new green reagent that will be widely used in fine chemistry, green chemistry, and industrial chemical processes.Pseudomonas aeruginosa exhibits a broad spectrum of intrinsic antibiotic resistance because of the limited permeability of its outer membrane. Given this situation, molecules that could make Gram-negative bacteria more permeable and more susceptible to large-scaffold Gram-positive antibiotics may be advantageous. Herein, we evaluate the antimicrobial activity of a series of targeted poly(ethylene glycol)-desferrioxamine/gallium (PEG-DG) conjugates that can improve the sensitivity of P. AZD3229 in vivo aeruginosa to the glycopeptide vancomycin (VAN). We observed that single-ended mPEG-DG and double-ended PEG-DG2 conjugates characterized by PEG MW ≥2000 synergistically enhanced the sensitivity of VAN against P. aeruginosa reference strains PAO1 and ATCC 27853 and three clinically isolated carbapenem-resistant strains, but not Escherichia coli strain ATCC 25922. Although the exact mechanism of this phenomenon is currently under investigation, PEG-DG conjugates enhanced nitrocefin (NCF), hexidium iodide (HI), and VAN permeability only when PEG and DG were directly conjugated. The two most important physicochemical factors contributing to the synergistic activity observed with VAN relate to (1) the final concentration of DG ligands conjugated to the polymer and (2) the polymer length, wherein MW ≥2000 yielded a similar fractional inhibitory concentration.Morphological control of C60 fullerene using liquefied porphyrins (1 and 2) as the host matrices was explored. Slow evaporation of the solvent of the equimolar mixture of porphyrin and C60 in toluene afforded the porphyrin/C60 composite with a 31 molar ratio. The stoichiometric binding behaviors suggest that specific porphyrin-C60 interactions operate the formation of the porphyrin/C60 composites, as corroborated by spectroscopic and thermal properties, and glazing-incidence wide-angle X-ray diffraction. Under the bulk conditions, the conventional thermodynamic advantage of multiple binding cooperativity for molecular recognition is unlikely to explain the stoichiometric binding behaviors. Instead, we propose a size-matching effect on the porphyrin-C60 interaction in the bulk porphyrin matrices, i.e., “supramolecular solvation”. The glassy nature of the porphyrin matrices was transmitted to C60 through the specific interaction, and the porphyrin/C60 composites adopted glassy states at room temperature.