Chinese Journal of Chemistry最新文献

Separating propylene (C₃H₆) from propane (C₃H₈) is a complex procedure in the petrochemical sector due to the comparable characteristics of the two gases. Herein, we reported the self-assembly phenomenon of NbOFFIVE-1-Ni (KAUST-7) crystals under different synthetic routes. The material features a decreased framework strain energy compared to original KAUST-7 and exhibits completely different adsorption performance, achieving the efficient separation of C₃H₆/C₃H₈ by synergetic effect of equilibrium and kinetics. The C₃H₆ adsorption capacity was as high as 46.2 cm³·g⁻¹ (298 K, 1 bar), increasing by 53% compared to the original material. The diffusion rates of C₃H₆ were faster than C₃H₈ as confirmed by time dependent kinetic adsorption profiles. It concurrently combines an excellent C₃H₆/C₃H₈ uptake ratio of 3.1 and kinetic selectivity (96.5) for C₃H₆/C₃H₈ separation with an equilibrium-kinetic combined selectivity of 42.5. Meanwhile, it can be regenerated easily due to moderate isosteric heat of adsorption (28.7 kJ·mol⁻¹). Breakthrough experiment for C₃H₆/C₃H₈ gas mixture was conducted and confirmed the high-purity recovery of C₃H₆ over C₃H₈. Moreover, it exhibited excellent water and moisture stability and can be easily synthesized through stirring at room temperature, which confers them with great potential for industrial application.

A divergent synthesis of spiroindenes through a palladium catalyzed cycloaddition between zwitterionic π-propargyl palladium species and benzofulvenes in moderate to good yields has been disclosed along with good functional group compatibility and a broad substrate universality. This protocol features a highly regioselective switchable process between [3+2] and [4+2] cycloadditions controlled by phosphine ligands with different bite angles. The reaction mechanism has been clarified by mechanistic studies and DFT calculations, rendering that the coordination modes of the ligands with the substrates and the bite angle of the ligands play critical roles in the product regioselectivity.

Herein we present a novel electrochemical method for the direct decarboxylative phosphorylation of α-amino acids to α-amino phosphonates, a key structural element in various biologically active compounds. This method bypasses the need for strong chemical oxidants and 2-step processes involving preliminary conversions, making it a more straightforward synthetic tool. Key to the success of the method is to establish a microenvironment on the anode surface in an acidic solution to facilitate selective anodic decarboxylation and subsequent C–P formation. The electrosynthetic process in continuous flow ensures benign conditions and excellent scalability through continuous production with parallel reactors.

The dearomatization of indole derivatives bearing amide functionalities presents a significant challenge due to the inherent stability of the amide carbonyl group, resulting from nitrogen lone-pair delocalization that imparts increased resonance stabilization. In this study, we report a visible-light photocatalytic intramolecular dearomatization of indole derivatives with amide groups, achieving the synthesis of spiroindolines via energy transfer. This method enables the efficient formation of a range of hydroxyl-substituted spiroindolines in moderate to high yields, with excellent diastereoselectivity (> 20 : 1) under mild reaction conditions. Control experiments confirmed the involvement of an energy transfer pathway in the reaction mechanism. Density Functional Theory (DFT) calculations further revealed π-π stacking interactions between the indole core and pyridine ring, along with the strengthening of hydrogen bonding between the pyridine nitrogen and hexafluoroisopropanol (HFIP) in the excited state. These interactions facilitated the energy transfer-mediated triplet excited state intermolecular proton transfer (T-ESPT), crucial for activating the otherwise amide functionality. This protocol represents a rare example of harnessing the reactivity of amide groups for dearomative transformations.

Compared to the conventional trial-and-error approach, computational prediction is becoming an increasingly prominent approach in the discovery of covalent organic frameworks (COFs) with specific applications, yet it has been rarely demonstrated. Herein, we employed density functional theory (DFT) to pre-screen the electronic and optical properties of thiophene-based donor-acceptor (D-A) pairs simplified from their corresponding COF structures. Theoretical calculation illustrates the BMTB-BTTC with the highest number of thiophene units is expected to exhibit the best photocatalytic performance for hydrogen production. According to calculation prediction, four COFs have been prepared and their photocatalytic activities have been experimentally validated. Interestingly, the corresponding BMTB-BTTC-COF shows the highest photocatalytic hydrogen production rate of 12.37 mmol·g^–1·h^–1 among the four COFs. Combining the calculation and experimental results, it has been proven that the photocatalytic activity can be fine-tuned by modulating the number of thiophene units. Our study provides a new strategy for the rational design and regulation of D-A COFs to enhance photocatalytic activity through computational prediction.