As an attractive and environmentally friendly propylene oxide (PO) production process, the direct epoxidation of propylene by metallic catalysts such as Ag and Cu with molecular oxygen has attracted extensive attention, but this process remains one of the biggest challenges in chemistry because the selective oxidation of propylene is influenced by the competitive reactions. It is well known that NaCl(KCl) can promote PO selectivity significantly, and in order to explore the possibility to enhance the PO selectivity by Na, K, and Cl additives, we used first-principles calculations in this work to explore the PO formation mechanism on pure and Na-, K-, and Cl-modified Ag(111). We have reported two parallel reaction pathways on the Ag(111) surface in detail: dehydrogenation and epoxidation. On the surface of Ag( 111), acrolein is obtained by two H-stripping reactions in the process of dehydrogenation. In addition, in the epoxidation reaction, PO and acetone/propanal can be obtained through a propylene oxametallacycle (OOMMP) intermediate. The crucial competitive steps of the selectivity of PO are the competitive reactions between the dehydrogenation reaction and the OOMMP intermediate formation reaction and the formation of PO and acetone/propanal. The present calculation results showed that the addition of alkali metal atoms (Na/K) had almost no effect on the first-step competitive reaction (allylic hydrogen stripping vs OOMMP) but could improve the selectivity of PO formation in the second-step competitive reaction, among which the Na atom had a better effect than the K atom. The addition of a Cl atom can not only improve the selectivity of OOMMP in the first competitive reaction but also improve the selectivity of PO in the second competitive reaction, and it is more significant in the first competitive reaction. The promotion effect for the PO formation selectivity follows the trend of Cl > Na > K. Through calculation, the selectivity of the target product (PO) was improved, and the insight obtained could provide theoretical guidance for further development of catalysts for propylene epoxidation.

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With distinct responses of three fluorescent bands, a single white-light-emitting MOF was constructed and applied in array sensing for berberine homologue discrimination.

A Cu-catalyzed protocol has been developed for the rapid construction of a wide spectrum of structurally interesting spiropyrroline skeletons. This method utilizes readily accessible ketoximes and alkenes as the starting materials and exhibits broad substrate scope and good functional group compatibility. Furthermore, the reaction can be applied for the late-stage modification of bioactive pregnenolone derivatives. The mechanistic investigation suggests that the reactions proceed through a radical process.

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Host-guest interactions play critical roles in achieving switchable structures and functionalities in porous materials, but design and control remain challenging. Here, we report a two-dimensional porous magnetic compound, [FeII(prentrz)2PdII(CN)4] (prentrz = (1E,2E)−3-phenyl-N-(4H-1,2,4-triazol-4-yl)prop-2-en-1-imine), which exhibits an atypical pore transformation that directly entangles with a spin state transition in response to water adsorption. In this material, the adsorption-induced, non-uniform pedal motion of the axial prentrz ligands and the crumpling/unfolding of the layer structure actuate a reversible narrow quasi-discrete pore (nqp) to large channel-type pore (lcp) change that leads to a pore rearrangement associated with simultaneous pore opening and closing. The unusual pore transformation results in programmable adsorption in which the lcp structure type must be achieved first by the long-time exposure of the nqp structure type in a steam-saturated atmosphere to accomplish the gate-opening adsorption. The structural transformation is accompanied by a variation in the spin-crossover (SCO) property of FeII, i.e., two-step SCO with a large plateau for the lcp phase and two-step SCO with no plateau for the nqp phase. The unusual adsorption-induced pore rearrangement and the related SCO property offer a way to design and control the pore structure and physical properties of dynamic frameworks.

Density functional theory calculations were performed to investigate the structural and energetic properties of trimetallic AuPdPt clusters with x + y + z = 7. The possible stable geometrical configurations with their electronic states are determined. We analyze the chemical order, binding energies, vertical ionization potential, electron affinity, and HOMO-LUMO gaps as a function of the whole concentration range. The affinity of AuPdPt clusters toward one O molecule is also evaluated in terms of the changes in geometry, adsorption energy, and charge transfer.

A useful Cu-catalyzed cycloaddition protocol for the construction of benzene rings has been achieved. The reactions, utilizing readily available oximes and maleimides as starting materials, proceed under mild reaction conditions to generate a series of structurally interesting fused-phthalimides that are difficult to be prepared by conventional methods.